Radiographic Dictionary

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  • 10-day rule= The practice of waiting 10 days after a woman’s menstrual flow to conduct a radiographic examination or study.
  • 15 percent rule= An increase in kvp by 15 percent that causes a doubling in exposure and vice versa.
  • Abdominal binder= a bandage or elasticized wrap that is applied around the lower part of the torso to support the abdomen. It is sometimes applied after abdominal surgery to decrease discomfort and support abdominal muscles.
  • Abdominal thrust= subdiaphragmatic force applied as a treatment for choking.
  • Abduct, abduction= to move away from the median plane of the body.
  • Abduct=To move an extremity outward, away from the torso. The humerus is abducted when it is elevated laterally.
  • Abductor tubercle=Round bony structure located posteriorly on the medial aspect of the femur, just superior to the medial condyle.
  • Aberration= Deviation from normal.
  • Abrasion= a scraping or rubbing away of a surface, such as skin or teeth, by friction.
  • Abscess= An encapsulated infection.
  • Abscess= Encapsulated collection of pus.
  • Absolute risk= the proportion of a population expected to get a disease over a specified time period.
  • Absolute= value The meaning of a number equal to the distance of that number from zero on the number line.
  • Absorbed dose= the amount of energy deposited by ionizing radiation in a unit mass of tissue. It is expressed in units of joule per kilogram (J/kg), and called “Gray” (Gy).
  • AC= Alternating current. Electric current that alternates or reverses polarity in a cyclical manner (e.g. 60 Hertz AC power)
  • Acanthiomeatal line=Imaginary line connecting the point where the upper lip and nose meet with the external ear opening.
  • Acceptance limits= The range of images determined to be of good quality by a given individual or department.
  • Acceptance testing= testing that occurs to ensure equipment or processes are functioning within acceptable limits.
  • Acceptance Testing=Quality control testing performed on new equipment on delivery and installation.
  • Accuracy=The extent to which a measurement is close to the true value.
  • Achalasia= Failure of the lower esophageal sphincter to relax because of absence or destruction of cells in the myenteric nerve plexus, which results in difficulty swallowing.
  • Acid-base balance= Stable concentration in body fluids
  • Acinus= Cluster of alveoli.
  • Acquired immunity= infection resistance to a specific organism that occurs after an individual has been infected with the organism, or that is conferred from a vaccine.
  • Acquired immunodeficiency syndrome (AIDS)= Impairment of cellular immunity
  • Acromegaly= An overgrowth of the hands, feet, face, and jaw resulting from hypersecretion of growth hormones.
  • Acromegaly= Gradual marked enlargement and thickening of the bones of the face and jaw.
  • Actinides= elements in the periodic table with atomic numbers from 90 to 103 (thorium to lawrencium); i.e., elements with a higher atomic number than actinium, which has an atomic number of 89. These are also called “rare earth metals.” They include most of the well-known elements found in nuclear reactions. Actinides with atomic numbers higher than 92 do not occur naturally but are produced artificially by bombarding other elements with particles. Some of the actinides include plutonium, curium, and californium.
  • Action=The activity to achieve the desired outcome.
  • Activator= A chemical used in film developing in the fixer solution to maintain an acidic ph to enhance the functioning of the clearing agent.
  • Active immunity= A person forms antibodies to counteract an antigen in the form of a vaccine or a toxoid.
  • Active Matrix Array (AMA)=A large-area (the size of conventional film/screen image receptors) integrated circuit that consists of millions of identical semiconductor elements deposited on a glass base that acts as the flat-panel image receptor.
  • Active osteomyelitis= Initial loss in bone tissue resulting from a bone infection.
  • Activity (radioactivity)= the property of certain nuclides of emitting radiation by spontaneous transformation of their nuclei. Various units of (radio)activity have been used including curie (1 Ci = 3.7 x 1010 disintegrations per second) and becquerel ( 1 Bq = 1 disintegration per second).
  • Activity= Describes the quantity of radioactive material; expressed as the number of radioactive atoms that undergo decay per unit time.
  • Actual focal spot= The physical area of the focal track that is impacted.
  • Actual Focal Spot=The actual area of the x-ray tube target from which x-rays are emitted.
  • Acute exposure= an exposure to radiation that occurred in a matter of minutes rather than in longer, continuing exposure over a period of time.
  • Acute pancreatitis= Active inflammation of the pancreas.
  • Acute Radiation Syndrome (ARS)= The Acute Radiation Syndrome (ARS) is also known as Radiation Sickness. A person exposed to radiation will develop ARS only if the radiation dose was high, penetrating (e.g., x-rays or gamma rays), encompassed most or all of the body, and was received in a short period of time. Clinical severity of the four subsyndromes of ARS (hematopoietic, cutaneous, gastrointestinal, and neurovascular) will vary with dose and host factors (e.g., young or old age, immunosuppression, and medical co-morbidity–especially extensive trauma and burns).
  • Acute= beginning abruptly with marked intensity or sharpness, then subsiding after a relatively short period.
  • Added filtration= Any filtration that occurs outside the tube and housing before the image receptor.
  • Additive condition= A disease that causes body tissues to thicken, increase in atomic number, or increase in density, requiring an increase in technical factors to achieve proper image receptor exposure.
  • Additive disease=Condition that results in change to the normal bony structures, soft tissues, or air or fluid content of the patient; may require technical changes to compensate for them prior to exposing the patient. Additive diseases cause the tissues to increase mass and density or thickness, resulting in them being more radiopaque.
  • Adduct, adduction= to move toward the median axis of the body.
  • Adduct=To move an extremity toward the torso. The humerus is adducted when it is positioned closer to the torso after being abducted.
  • Adenocarcinoma= Malignancy of glandular tissue.
  • Adenoma= Benign epithelial neoplasm that grows in a glandlike structure.
  • Adenopathy= Enlargement of the lymphatic glands.
  • Adhesive= A thin coating applied to the base material before it is coated with the emulsion to prevent bubbles or other distortion during processing or handling.
  • Admittance= The measure of resistance in an AC current when the expression 1/R is used.
  • Adnexal= Pertaining to the uterine appendages (ovaries, fallopian tubes, and ligaments).
  • Adult respiratory distress syndrome (ARDS)= a respiratory disorder characterized by respiratory insufficiency and hypoxemia.
  • Adult respiratory distress syndrome (ARDS)= Severe pulmonary congestion due to diffuse injury to the alveolar-capillary membrane.
  • Advance directive= a document that outlines specific wishes about medical care to be followed in the event that an individual loses the ability to make or communicate health care decisions.
  • Adverse Event=A harmful or unintended incident that may occur during any diagnostic procedure.
  • Aerophagia= A psychological disorder resulting in abnormal swallowing of air.
  • Afferent= To carry toward the center.
  • Afterglow= Delayed phosphorescent emission; also called screen lag.
  • Agenesis= Absence of an organ.
  • Aggravate= to worsen.
  • Aggregate Data Indicator=Quantifies a process or outcome related to many cases.
  • Aggressiveness= undesirable behavior characterized by anger or hostility.
  • Agitation= Stirring up of the processing solutions.
  • Agitation=Stirring, swirling, or shaking of processing solutions.
  • Air burst= a nuclear weapon explosion that is high enough in the air to keep the fireball from touching the ground. Because the fireball does not reach the ground and does not pick up any surface material, the radioactivity in the fallout from an air burst is relatively insignificant compared with a surface burst.
  • Air core transformer= Arrangement of two coils of wire in proximity to facilitate induction.
  • Air kerma= the initial kinetic energy of the primary ionizing particles (photoelectrons, Compton electrons, positron/negatron pairs from photon radiation, and scattered nuclei from fast neutrons) produced by the interaction of the incident uncharged radiation in a small volume of air, when it is irradiated by an x-ray beam. Unit of measure is Gray.
  • Air kerma= The kinetic energy released per unit of mass air.
  • Airborne contamination= mode of transmitting infection by dust containing spores or droplet nuclei, which are particles measuring 5 microns or smaller that contain microorganisms and remain suspended in the air for long periods of time.
  • Air-gap technique=Technique of positioning the patient at a distance (10–15cm) from the image receptor (IR) to reduce the amount of scatter radiation that reaches the IR and increase radiographic contrast.
  • ALARA principle= a principle that states that all radiation exposure to humans should be limited to levels that are as low as reasonably achievable.
  • ALARA= acronym for “As Low As Reasonably Achievable,” means making every reasonable effort to maintain exposures to ionizing radiation as far below the dose limits as practical. This is a key principle in radiation protection and safety.
  • ALARA= As low as reasonably achievable.
  • ALARA=Acronym for keeping radiation exposure “as low as reasonably achievable.”
  • Alcoholic gastritis= Inflammation of the stomach lining caused by alcohol.
  • Algebraic expression= A mathematical sentence or term consisting of letters and/or numbers that are multiplied, divided, added, subtracted, or raised to a power. Aliasing Occurs when spatial frequency exceeds the Nyquist frequency and the incoming data are sampled less than twice per cycle.
  • Algorithm=Set of rules or directions for getting a specific outcome from a specific input.
  • Align=To bring into line or alignment. The lower leg and foot are aligned at a 90-degree angle with each other for a lateral foot image.
  • Allergen= an agent that causes an allergic response.
  • Allergic reaction, allergic response= an unfavorable physiological response to an allergen, a substance to which an organism has previously been exposed and to which it has developed antibodies.
  • Allergy, allergenic= a hypersensitive reaction to intrinsically harmless antigens. Allergenic describes an individual prone to allergic response.
  • Alleviate= to relieve or to partially remove or correct.
  • Alloy = metal made by mixing two or more metals.
  • Alpha particle= Contains two protons and two neutrons, is equivalent to a helium nucleus, and is emitted from the nuclei of heavy elements as they undergo radioactive decay; has a great mass and a positive charge.
  • Alpha particle= the nucleus of a helium atom, made up of two neutrons and two protons with a charge of +2. Certain radioactive nuclei emit alpha particles. Alpha particles generally carry more energy than gamma rays or beta particles, and deposit that energy very quickly while passing through tissue. Alpha particles can be stopped by a thin layer of light material, such as a sheet of paper, and cannot penetrate the outer, dead layer of skin. Therefore, they do not damage living tissue when outside the body. When alpha-emitting atoms are inhaled or swallowed, however, they are especially damaging because they transfer relatively large amounts of ionizing energy to living cells.
  • Alternating current (AC)= Electrons move first in one direction and then reverse and move in the opposite direction.
  • Alternating Current (AC)=Electric current that alternates or reverses polarity in a cyclical manner (e.g. 60 Hertz AC power)
  • Alveolar, or air-space, pneumonia= Inflammatory exudates that replace air and cause the affected lung to become solid.
  • Alzheimer’s disease= a progressive mental deterioration characterized by confusion, memory failure, disorientation, restlessness, agnosia, speech disturbances, inability to carry out purposeful movement, and hallucinosis.
  • AM= Amplitude modulation.
  • Ambient air= the air that surrounds us.
  • Ambulatory= able to walk, hence describing a patient who is not confined to bed or designating a health service for people who are not hospitalized.
  • Ameba (also amoeba)= a microscopic, single-celled, parasitic organism.
  • Amebiasis= an infection of the intestine or liver by species of pathogenic amebas acquired by ingesting food or water contaminated with infected feces.
  • Americium (Am)= a silvery metal; it is a man-made element whose isotopes Am-237 through Am-246 are radioactive. Am-241 is formed spontaneously by the beta decay of plutonium-241. Trace quantities of americium are widely used in smoke detectors and as neutron sources in neutron moisture gauges.
  • Ammeter= A device used to measure current connected in a series; measured in amperes.
  • Amniocentesis= an obstetrical procedure in which a small amount of amniotic fluid is removed for laboratory analysis.
  • Amorphous= Without shape or definite form .
  • Amorphous=Without form.
  • Amp (A)= The unit of current; also known as the ampere.
  • Ampacity= Current handling capability expressed in amperes. The maximum current a conductor can carry without being heated beyond a safe limit.
  • Ampere (A)= The unit of current; also known as the amp.
  • Amplitude= The intensity of the wave defined by its maximal height.
  • Amplitude= The magnitude of a current or voltage. It can be the maximum, minimum, average, or RMS value of an alternating current (AC) signal. These four magnitudes are the same for a direct current (DC) signal.
  • Amplitude= with respect to a sine wave, the distance between peak and trough.
  • Ampule= a small, sterile glass or plastic container that usually contains a single dose of a solution.
  • Analgesic= a drug that relieves pain.
  • Analog computer= A machine that handles data composed of continuously varying electrical currents.
  • Analog Signal= An electrical signal which varies continuously, not having discrete values. Analog signals are copies or representations of other waves in nature. An analog audio signal, for instance, is a representation of the pressure waves which make up audible sound.
  • Analog= Representation of data by continuously variable quantities as opposed to a finite number of discrete quantities in digital.
  • Analog-to-Digital Convertor (ADC)=Device for converting an analog electronic signal into a digital electronic signal for processing by a computer.
  • Anaphylactic= Reactions are characterized by hypotension and vascular collapse (shock) with urticarial (hives), bronchiolar spasm, and laryngeal edema.
  • Anaphylaxis, anaphylactic, anaphylactoid= an exaggerated, life-threatening hypersensitivity reaction to a previously encountered antigen. Penicillin injection is the most common cause of anaphylactic shock.
  • Anaplastic= without form.
  • Anasarca= Pronounced swelling of subcutaneous tissues throughout the body.
  • Anastomosis= a connection between two vessels or a surgical joining of two ducts, blood vessels, or bowel segments to allow flow from one to the other.
  • Anatomic position=Refers to positioning the patient with the arms and legs extended and the face, arms, hands, legs, and feet placed in an anteroposterior (AP) projection. This is the starting point from which imaging procedures are referenced.
  • Anatomically programmed radiography= A computerized exposure control system; technique charts using existing exposure systems that are stored in the data memory banks.
  • Androgens= any steroid hormone that increases male characteristics.
  • Anechoic= Not producing internal echoes (on ultrasound).
  • Anemia= a decrease in hemoglobin in the blood to a level below 10 g/dl, or a decrease in the number of red blood cells to levels below the normal range of 4.2 million/mm3 to 6.1 million/mm3.
  • Anemia= Decreased hemoglobin in the blood below normal levels.
  • Anesthetic, anesthesia= a drug or agent that is capable of producing a complete or partial loss of feeling (anesthesia).
  • Aneurysm= a localized dilation of the wall of a blood vessel.
  • Aneurysmal bone cyst= Consists of numerous blood-filled arteriovenous communications.
  • Angina pectoris= a paroxysmal thoracic pain that may radiate down the inner aspect of the left arm and is frequently accompanied by a feeling of suffocation and impending death. It is caused by spasm or occlusion of a coronary artery and is treated by administration of nitroglycerine.
  • Angiocardiogram= a series of radiographic images demonstrating vessels of the heart.
  • Angioedema= an acute, painless, dermal, subcutaneous, or submucosal swelling of short duration. It involves the face, neck, lips, larynx, hands, feet, genitalia, or viscera.
  • Angiogram, angiography= a radiographic image/examination of a blood vessel into which a contrast medium has been injected.
  • Angioma= Tumor composed of blood vessels.
  • Angioplasty= the reconstruction of blood vessels damaged by disease or injury.
  • Angulation= Indicates an angular deformity between the axes of the major fracture fragments.
  • Ankylosis= Immobility and consolidation of a joint caused by disease, injury, or surgical procedure.
  • Annihilation reaction= Matter being converted back into energy as a result of a positron combining with a negative electron, which creates two photons moving in opposite directions.
  • Annihilation= Interaction produces two high-energy photons (gamma rays) in opposite directions (separated by 180 degrees).
  • Anode assembly= Consists of the anode, stator, and rotor.
  • Anode cooling chart= Permits the calculation of the time necessary for the anode to cool enough for additional exposures to be taken.
  • Anode heel effect= Due to the geometry of the angled anode target, the radiation intensity is greater on the cathode side.
  • Anode heel effect=Absorption of radiation in the heel of the anode that results in less x-ray intensity at the anode side of a long IR when compared to the cathode side.
  • Anode= the electrode at which oxidation occurs. Also, the electrically positive, target end of an x-ray tube.
  • Anode= The positive side of the x-ray tube; serves as a target surface for high-voltage electrons from the filament, conducts the high voltage from the cathode back into the x-ray generator circuitry, and serves as the primary thermal conductor.
  • Anomaly= deviation from what is regarded as normal; a congenital malformation, such as the absence of a limb or the presence of an extra finger.
  • Anorexia nervosa= A psychological eating disorder.
  • Anorexia= lack or loss of appetite, resulting in the inability to eat.
  • Anoxia= an abnormal condition characterized by a lack of oxygen. It may result from an inadequate supply of oxygen to the respiratory system, from an inability of the blood to carry oxygen to the tissues, or from an inability of the tissues to absorb the oxygen.
  • Antecubital= in front of the elbow; at the bend of the elbow.
  • Anterior (antero-)=Refers to the front surface of the patient, used to express something situated at or directed toward the front; includes the palms and tops of the feet as in anatomic position. The sternum is anterior to the vertebral column.
  • Anterior shoulder dislocation=Condition in which the humeral head is demonstrated anteriorly beneath the coracoid.
  • Anthrax= a disease caused by the bacterium Bacillus anthracis, affecting primarily farm animals.
  • Antiallergic= pertaining to a medication used to treat allergies, or one administered in advance to patients who might be expected to have an allergic reaction.
  • Antibacterial= pertaining to a substance that kills bacteria or inhibits their growth or replication.
  • Antibiotic= an antimicrobial agent used to treat infections.
  • Antibodies= Body’s counteraction to control antigens.
  • Antibody= an immunoglobulin produced by lymphocytes in response to bacteria, viruses, or other antigenic substances. An antibody is specific to an antigen. Antibodies are responsible for acquired immunity and for allergic responses.
  • Anticholinergic= pertaining to a blockade of acetylcholine receptors that inhibits the transmission of parasympathetic nerve impulses, thus inhibiting secretions.
  • Anticoagulant= Substance that suppresses or delays coagulation of the blood.
  • Anticonvulsant= pertaining to a substance or procedure that prevents or reduces the severity of epileptic or other convulsive seizures.
  • Antidote= a drug or other substance that opposes the action of a poison.
  • Antifungal= pertaining to a substance that kills fungi or inhibits their growth or reproduction.
  • Antigen= a substance, usually a protein, that causes the formation of an antibody that reacts specifically with that antigen.
  • Antigens= Body’s ability to recognize foreign substances.
  • Antihalation coating= A substance applied to the back of a single-emulsion film designed to absorb light coming from the emulsion and preventing backscatter.
  • Antihistamine= any substance capable of reducing the physiological and pharmacological effects of histamine. Antihistamines include a wide variety of drugs that block histamine receptors. Used to treat allergies.
  • Antihypertensive= pertaining to a medication, substance, or procedure that reduces high blood pressure.
  • Antimicrobial= an agent that kills or inhibits the growth or replication of microorganisms.
  • Antiseptic= a substance that tends to inhibit the growth and reproduction of microorganisms.
  • Aortic aneurysm= A large dilation of the aorta.
  • Aortic valve= Valve between the left ventricle and aorta.
  • Aortogram, aortography= a radiographic image/examination of the aorta made after the injection of a radiopaque contrast medium.
  • Aperture diaphragm= A flat sheet of metal, usually lead, with a hole cut in the center and attached to the x-ray port.
  • Apex, apical= the top, the end, or the tip of a structure, such as the apex of the heart.
  • Aphasia, aphasic= an abnormal neurological condition in which language function is defective or absent because of an injury to certain areas of the cerebral cortex.
  • Aplasia= Lack of normal development resulting in a small size or developmental failure resulting in the absence of an organ or tissue.
  • Application service provider (asp)= company that provides outsourcing of archiving and management functions for a pay-per-use or pay-per-month charge.
  • Appositional growth= Flat bones grow in size by the addition of osseous tissue to their outer surfaces.
  • Appropriateness of Care=Whether the type of care is necessary.
  • Approximate entrance skin exposure= An estimation of the dose of radiation related to a specific type of radiologic exam or procedure.
  • Aqueous= describing a solution prepared with water.
  • Arachnodactyly= Congenital condition of long, thins piderlike fingers and toes.
  • Arachnoid membrane= Middle meningeal covering.
  • Arachnoid villa= Projections of fibrous tissue from the arachnoid membrane.
  • Archival Film=Film images made before 1974 and containing 20% more silver than film made afterward.
  • Archival Quality=How well an image can be stored over time.
  • Archive query= software function that allows historical information to be gathered from digital storage, such as multiple examinations, a range of dates, or by pathology.
  • Archive server= consists of the physical storage device of the archive system; it commonly consists of two or three tiers of storage.
  • Archive= historical collection of images stored in PACS.
  • Armature= A coil of wire that acts as a conductor.
  • Array detection= Information received from an entire area at once.
  • Arteriogram, arteriography= an x-ray image/examination of an artery injected with a radiopaque medium.
  • Arteriovenous malformation= Abnormal communication between an artery and a vein.
  • Arthritis, arthritic= an inflammatory condition of a joint.
  • Arthrography= a method of radiographically visualizing the inside of a joint using a radiolucent or radiopaque contrast medium.
  • Arthropod= a form of animal life that may cause allergic reactions and may serve as a vector for viruses or other disease-causing agents. Arthropods generally are distinguished by a jointed exoskeleton (shell) and paired, jointed legs. This group includes crustaceans, insects, and similar animal forms.
  • Articulation=Joint or place where two bones meet.
  • Artifact=The appearance in a diagnostic image of anything that is not a part of the patient’s anatomy.
  • Artifact=Undesirable structure or substance recorded on the image. It may or may not be covering information.
  • Artifacts= avoidable extraneous information on the image that interferes or distracts from image quality.
  • Artificial permanent magnet= Manufactured from steel alloy called alnico, composed of aluminum, nickel, and cobalt.
  • As Low as Reasonably Achievable (ALARA)=Philosophy of keeping radiation exposure to a minimum.
  • Ascites= Accumulation of fluid in the abdominal cavity.
  • Ascites= Fluid accumulation within the peritoneal cavity.
  • Asepsis= the absence of microorganisms.
  • Aseptic necrosis= Cystic and sclerotic degeneration caused by injury, not infection.
  • Aseptic necrosis= Death of tissue.
  • Aspect ratio= ratio of the width of the monitor to the height of the monitor.
  • Aspect Ratio=The ratio of the width of the image displayed on a computer or video monitor to the height of the display.
  • Aspirate, aspiration= to withdraw fluid or air from a cavity, or to inhale fluid or a solid object into the lungs.
  • Assault= the threat of touching in an injurious way.
  • Assertiveness= a desirable behavior characterized by a calm, firm expression of feelings or opinions.
  • Assigned Protection Factor= Assigned Protection Factor (APF) means the workplace level of respiratory protection that a respirator or class of respirators is expected to provide to employees enrolled in a continuing, effective respiratory protection program.
  • Asthma, asthmatic= a respiratory disorder characterized by recurring episodes of paroxysmal dyspnea, wheezing caused by constriction of the bronchi, coughing, and viscous mucoid bronchial secretions.
  • Asthma= Widespread narrowing of the airways as a result of exposure to stimuli.
  • Astrocytoma= Primary tumor of the brain composed of astrocytes.
  • Asymptomatic= without symptoms.
  • Asystole= a life-threatening cardiac condition characterized by the absence of electrical and mechanical activity in the heart.
  • Atelectasis= an abnormal condition characterized by the collapse of a lung or portion of a lung, preventing the respiratory exchange of carbon dioxide and oxygen. In newborns, atelectasis is the term for incomplete lung expansion.
  • Atelectasis= Collapse of the lung.
  • Atherectomy= surgical removal of an atheroma in a major artery.
  • Atheroma= an abnormal mass of fat or lipids, as in a sebaceous cyst or in deposits in an arterial wall.
  • Atherosclerosis= a common disorder characterized by yellowish plaques of cholesterol, other lipids, and cellular debris in the inner layers of the walls of arteries.
  • Atom = the building block of molecules and all things. Atoms are made of a nucleus of protons and neutrons surrounded by orbiting electrons.
  • Atom= the smallest particle of an element that can enter into a chemical reaction.
  • Atom= The smallest particle of an element that still possesses the chemical properties of that element.
  • Atomic mass number (A)= The mass of an atom; used when precision is not necessary; is equal to the number of protons and neutrons in the nucleus of an atom.
  • Atomic mass number= the total number of protons and neutrons in the nucleus of an atom.
  • Atomic mass unit (amu)= 1 amu is equal to one twelfth of the mass of a carbon-12 atom.
  • Atomic mass unit (amu)= The mass of the particles of an atom.
  • Atomic number= The number of nuclear protons in an atom unique to each element; also known as the Z number.
  • Atomic number= the total number of protons in the nucleus of an atom.
  • Atomic reactor= A device that converts nuclear energy to electrical energy.
  • Atomic weight= the mass of an atom, expressed in atomic mass units. For example, the atomic number of helium-4 is 2, the atomic mass is 4, and the atomic weight is 4.00026.
  • Atresia= Congenital absence or closure of a normal body orifice or tubular organ.
  • Atrial septal defect= Congenital anomaly resulting in an opening between the atria.
  • Atrium= a chamber or cavity, such as the right and left atria of the heart.
  • Atrophy= A wasting away of body tissue with diminished cell proliferation.
  • Atrophy= Diminished size as a result of wasting away.
  • Atropine= an alkaloid anticholinergic drug that blocks parasympathetic stimuli by raising the threshold of response of effector cells to acetylcholine.
  • Attenuate, attenuation= the process of reduction, such as the reduction of x-ray beam intensity when it penetrates matter.
  • Attenuation= The reduction in the number of x-ray photons in the beam, and subsequent loss of energy, as the beam passes through matter.
  • Attenuation=The decrease in magnitude of a signal as it travels through any transmitting medium, such as a cable or circuitry. Attenuation is usually expressed logarithmically as the ratio of the original and decreased signal amplitudes. It is usually expressed in decibels (db).
  • Aura= a sensation, as of light or warmth, that may precede an attack of migraine or an epileptic seizure.
  • Aurora = bands of light that appear near the polar regions of earth, usually at night. These bands are due to the impact of charged particles from the sun on the upper atmosphere, where they are directed by earth’s magnetic field to the magnetic poles.
  • Autoclave= an appliance used to sterilize medical instruments or other objects with steam under pressure.
  • Automatic Brightness Control (ABC)=Also called automatic brightness stabilization (ABS), it is an electronic method of regulating fluoroscopic image brightness level for variations of patient thickness and attenuation.
  • Automatic Brightness Stabilization=Electronic method of regulating fluoroscopic image brightness. Also known as automatic brightness control.
  • Automatic data recognition= processing mode in which the computer analyzes data according to set parameters.
  • Automatic Exposure Control (AEC)=Electronic system that terminates the x-ray exposure once an adequate amount of radiation has been emitted.
  • Automatic exposure control (AEC)=System used in radiography that automatically determines image density by stopping the exposure when adequate intensity has reached the IR.
  • Automatic exposure control= A device programmed to terminate the radiographic exposure time; also called automatic exposure device.
  • Automatic exposure device= A device programmed to terminate the radiographic exposure time; also called automatic exposure control.
  • Automatic Gain Control=Electronic method of regulating image brightness.
  • Automatic implantable cardioverter defibrillator (ICD)=Used to detect heart arrhythmias and then deliver an electrical shock to the heart to convert it to a normal rhythm.
  • Automatic rescaling= occurs when exposure is greater or less than the optimal amount to produce a diagnostic image; it is the effort of the computer to “fix” exposure errors.
  • Automatic rescaling=Final phase of image processing in digital radiography during which the computer compares the image histogram with the selected lookup table and applies algorithms to the raw data to align the image histogram with the lookup table.
  • Autonomic nervous system= Regulates involuntary body functions.
  • Autonomy= the quality of having the ability or tendency to function independently.
  • Autosomes= All chromosomes except gender.
  • Autotransformer= A transformer that automatically sets by adjustments.
  • Average gradient= The average slope of the D log E curve at the straight line portion of the curve.
  • Avoirdupois Ounce=Unit of weight in the English system more commonly known as the standard ounce.
  • Avulsion fracture= Small fragments torn from bony prominences.
  • Axial Resolution=Minimum reflector spacing along the axis of an ultrasound beam that results in separate, distinguishable echoes on the display.
  • Axilla, axillary= a pyramid-shaped space forming the underside of the shoulder between the upper arm and the side of the chest. Also called armpit. An axillary temperature is taken with the thermometer probe in the axilla.
  • Background radiation= ionizing radiation from natural sources, such as terrestrial radiation due to radionuclides in the soil or cosmic radiation originating in outer space.
  • Background Radiation=Radiation exposures from naturally occurring radioactivity and extraterrestrial cosmic radiation.
  • Backing layer= soft polymer that protects the back of the cassette.
  • Backscatter radiation= Photons that deflect back toward the source, traveling in the opposite direction of the incident photon.
  • Backscatter= x-rays scattered back in the direction of the incident x-ray beam.
  • Backup timer=Maximum time that the AEC x-ray exposure will be allowed to continue before automatically shutting off.
  • Bacteremia= Bacteria spread through the circulatory system.
  • Bacterial (phlegmonous) gastritis= Inflammation of the stomach lining caused by a bacterial infection.
  • Bacterial meningitis= Infection of the membranes covering the brain and spinal cord caused by bacteria.
  • Bacterium (plural, bacteria)= small, unicellular microorganism.
  • Band-pass filtering= Amplifies or deletes all but a selected range or band of frequencies.
  • Bandwidth= The frequency response from the incoming signal.
  • Bandwidth=The difference between the upper and lower limits of a given band of frequencies. It is expressed in hertz.  The range of frequencies that a transmitted communications signal occupies or that a receiving system can accept.  For example, it takes more bandwidth to download a photograph in a second than to download a page of text.  Virtual reality and three=dimensional audio/visual presentations require even more.
  • Bandwidth=The range of frequencies that can be satisfactorily transmitted or processed by a system.
  • Barbiturate= a derivative of barbituric acid that acts as a sedative or hypnotic by depressing the central nervous system and causing a decrease in the respiratory rate, blood pressure, and temperature.
  • Barcode label= label attached either to the cassette or to the imaging plate that identifies the plate for the purpose of matching the examination to the plate.
  • Barium fluorohalide= photostimulable phosphor located in the imaging plate.
  • Barium impaction= solidification of barium sulfate suspension in the intestine causing constipation and potential bowel obstruction.
  • Barium sulfate, “barium”= a radiopaque medium used as a diagnostic aid in gastrointestinal radiography.
  • Basal ganglia= Islands of gray matter, which is largely composed of cell bodies.
  • Base + Fog=Inherent optical densities in film resulting from the tint added to the base of the film and silver grains not exposed to radiation.
  • Base of support= the portion of the body in contact with a horizontal surface, such as the floor.
  • Base plus fog= The density at no exposure; the density that is inherent in the film.
  • Base= The base material that the film is made from; it is usually polyester, tough, stable, rigid, and uniformly lucent; it usually contains a blue tint.
  • Basic input/output system (bios)= contains a simple set of instructions for the computer to perform several basic functions, such as boot up, run hardware diagnostics, interpret keyboard signals, and so on.
  • Basophil= Granulocyte white blood cell.
  • Battery= A device that converts chemical energy into electrical energy.
  • Battery= the unlawful use of force against a person.
  • B-cell= a cell with the ability to produce an immune response induced by B-lymphocytes. Contact with a foreign antigen stimulates B-cells to differentiate into plasma cells that release antibodies.
  • Becquerel (Bq)= the amount of a radioactive material that will undergo one decay (disintegration) per second.
  • Becquerel= The SI unit for activity.
  • Bel= A unit that represents the logarithm of the ratio of two levels. One bel equals the base 10 logarithm of the ratio of two power levels. It is also equal to the base 10 logarithm of square of the ratio of two voltage or current levels, provided the impedances are the same at the two levels. See db.
  • Bence Jones protein= Abnormal protein typically found in the blood of patients with multiple myeloma.
  • Benchmarking=Involves comparing one organization’s performance with that of another.
  • Benign= not recurrent or progressive, not malignant.
  • Benign= Tumors that closely resemble their cells of origin in structure and function and remain localized.
  • Benzodiazepine= one of a group of psychotropic agents prescribed to alleviate anxiety or to treat insomnia.
  • Beryllium Window=A portion of the mammographic x-ray tube where the useful beam exits.
  • Beta burns= Energetic beta particles with high enough specific-activity, if left on the skin surface for a sufficient length of time, may cause erythema and dry (or even wet) desquamation. These are often called “beta burns.” “Beta burns” have been described after a nuclear weapon detonation as a consequence of fallout on the skin.
  • Beta particle= Identical to an electron, except it is emitted from the nuclei of radioactive materials; it is very light and negatively charged.
  • Beta particles= electrons ejected from the nucleus of a decaying atom. Although they can be stopped by a thin sheet of aluminum, beta particles can penetrate the dead skin layer, potentially causing burns. They can pose a serious direct or external radiation threat and can be lethal depending on the amount received. They also pose a serious internal radiation threat if beta-emitting atoms are ingested or inhaled.
  • Beta-blocker= a popular term for beta-adrenergic blocking agents used to treat hypertension, rapid heart rate, and sometimes migraine headaches.
  • Bias focusing= Engagement of a small focal spot while a negative voltage that is applied to the focusing cup acts to reduce the size of the electron stream, creating a smaller focal spot.
  • Bilateral=Both sides.
  • Bile= a bitter, yellow-green secretion of the liver that is stored in the gallbladder and released into the digestive tract to aid in the digestion of fats.
  • Biliary= pertaining to bile or to the gallbladder and bile ducts, which transport bile.
  • Bilirubin= the orange-yellow pigment of bile, formed principally by the breakdown of hemoglobin in red blood cells after termination of their normal lifespan. Also, a measurement of the bilirubin content of blood as a clinical test of biliary function.
  • Binary code= machine language of 1s and 0s.
  • Binary machine language= Language used by computers that operates with a two-symbol alphabet; 0 for off or 1 for on.
  • Bioassay= a measurement of radioactive materials present inside a person’s body through analysis of the person’s blood, urine, feces, or sweat.
  • Bioassay=The laboratory determination of the concentration of a drug or other substance in a specimen.
  • Biodosimetry= The use of physiological, chemical or biological markers of exposure of human tissues to ionizing radiation for the purpose of reconstructing doses to individuals or populations.
  • Biological Effects of Ionizing Radiation (BEIR) Reports= reports of the National Research Council’s committee on the Biological Effects of Ionizing Radiation.
  • Biological half-life= the time required for one half of the amount of a substance, such as a radionuclide, to be expelled from the body by natural metabolic processes, not counting radioactive decay, once it has been taken in through inhalation, ingestion, or absorption.
  • Biopsy= the removal of a small piece of living tissue from an organ or other part of the body for microscopic examination to confirm or establish a diagnosis, estimate prognosis, or follow the course of a disease.
  • Bismuth= a reddish, crystalline, trivalent metallic element. It is combined with various other elements, such as oxygen, to produce numerous salts used in the manufacture of many pharmaceutical substances.
  • Bit= Binary digits.
  • Bit= single unit of data
  • Bit=Binary digit; the smallest unit of computer memory that holds one of two values, one or zero.
  • Blowout fracture= Break in the floor of the orbit.
  • Blur= The streaking or smearing that results in the loss of nearly all recorded detail of objects outside the focal plane.
  • Body habitus=Body physique or type. Hypersthenic, sthenic, asthenic, and hyposthenic habitus are discerned in radiography to determine the size of IR to use and locations of the thoracic and peritoneal structures.
  • Body mechanics= the principles of proper body alignment, movement, and balance.
  • Bolus (injection)= a quantity of undiluted contrast medium or other fluid injected intravenously over a short period of time.
  • Bone islands= Solitary, sharply demarcated areas of dense compact bone.
  • Bony trabeculae=Supporting material in cancellous bone. It is demonstrated on an image as thin white lines throughout a bony structure and is evaluated for changes.
  • Booster=An amplifier inserted into a cable to increase the signal amplitude in order to compensate for signal loss due to attenuation. This extends the transmission range of the cable. Transformers may be employed to boost ac voltages. The term booster is also applied to amplifiers used in television receiving antenna systems.
  • Bougienage= Passage of an instrument through a tubular structure to increase its caliber (as in the treatment of a stricture of the esophagus).
  • Boundaries of an image.
  • Bowel obstruction= Abnormal accumulation of air and fluid resulting from a blockage in the bowel.
  • Bowel obstruction= blockage of the intestine. Acute bowel obstruction is very painful and may be life threatening if untreated.
  • Bowing fracture= Plastic deformation caused by a stress.
  • Bowman’s capsule= Cup-shaped end of renal tubule.
  • Boxer’s fracture= Fracture of the neck of the 5th metatarsal with a dorsal angulation.
  • Bradycardia= a heart condition in which the ventricles contract at a rate of fewer than 60 beats/min.
  • Bradypnea= an abnormally low respiratory rate.
  • Brainstorming=A group process used to develop a large collection of ideas without regard to their merit or validity.
  • Breakdown Voltage=The voltage at which the insulation between two conductors will fail and allow electricity to conduct or ‘arc’.
  • Breathing technique=Technique in which a long exposure time (3–4 seconds) is used with costal breathing to blur the chest details surrounding the structure of interest.
  • Bremsstrahlung interaction= An incident electron interacts with the force field of the nucleus, causing the incident electron to slow down, thus diverting the electron’s course. The electron loses energy and changes direction. The energy lost is a bremsstrahlung photon, and the photon energy is half the difference between the entering and exiting kinetic energy of the electron.
  • Brightness Gain=The degree of image brightness increase obtained with an image intensifier.
  • Brightness= The concept of density as it is displayed on a soft-copy monitor for digitial images.
  • Brightness=Describes the degree of luminance seen on the display monitor and refers to the degree of lightness (white) or lack of lightness (black) of the pixels in the image.
  • Broadband=The technique used to multiplex multiple networks on a single cable without interfering with each other.  Technologies that allow you to transmit or receive higher volumes of data at higher speeds.
  • Bromide Drag=Decrease in optical density caused by halides being deposited on trailing areas of the film during automatic processing.
  • Bronchial adenomas= Neoplastic growth of glandular structures in the bronchi.
  • Bronchiectasis= Chronic dilatation of the bronchi or bronchioles.
  • Bronchiectasis= Chronic dilation of the bronchi.
  • Bronchiolar (alveolar cell) carcinoma= Malignant neoplastic growth of the bronchioli spreading into the alveolar surface.
  • Bronchioloalveolar carcinoma= Adenocarcinoma of epithelial cells projecting into the alveolar spaces.
  • Bronchodilation= an increase in the diameter of the bronchial lumen, allowing increased airflow to and from the lungs.
  • Bronchogenic carcinoma= Primary malignancy arising from the mucosa of the bronchial tree.
  • Bronchoscopy= the visual examination of the tracheal and bronchial tree using a flexible fiberoptic instrument called a bronchoscope.
  • Bronchospasm= an abnormal contraction of the smooth muscle of the bronchi, resulting in an acute narrowing and obstruction of the respiratory airway, causing dyspnea.
  • Brush= A device, attached to slip rings that allows the circuit to remain stationary while the armature rotates without breaking the electrical contact between them.
  • Buccal= pertaining to the inside of the cheek, or to the surface of a tooth or the gum beside the cheek. The buccal route of medication administration involves placement of a drug in paste form on the buccal surface of the mouth.
  • Bucky= a moving grid that limits the amount of scatter radiation reaching a radiographic image receptor, thereby increasing the image contrast.
  • Bucky=Refers to the Potter-Bucky diaphragm, a device underneath the imaging table that holds the IR and contains a grid to prevent scatter radiation from reaching the IR.
  • Bullae= Large air-containing space.
  • BUN= abbreviation for blood urea nitrogen, a clinical laboratory test of kidney function.
  • Burn= the partial or complete destruction of skin caused by some form of energy, usually thermal energy.
  • Burner= device that burns data onto a CD or DVD
  • Bus topology= type of network setup in which each of the computers and network devices are connected to a single cable.
  • Bus= series of connections, controllers, and chips that creates the information highway of the computer.
  • Butterfly fragment= Elongated triangular fragment of cortical bone generally detached from two other larger fragments of bone.
  • Byte= An 8-bit word.
  • Byte= made up of 8 bits and is the amount of memory needed to store one alphanumeric character.
  • Cachexia= Ill health and malnutrition marked by weakness and emaciation that is usually associated with severe disease processes.
  • Calcified stones= Calcium deposits in the form of stones that can be found in the gallbladder and kidneys.
  • Calibrate= To adjust a tool of measurement to zero. Caliper A device used to measure part thickness.
  • Callus= New bone tissue that reunites the parts of a fracture.
  • Can be angled according to need.
  • Cancellous bone= Spongy bone of the medullary cavity and bony trabeculae.
  • Cancer= a neoplasm characterized by the uncontrolled growth of anaplastic cells that tend to invade surrounding tissue and to metastasize to distant body sites.
  • Cancer= Collectively, malignant tumors.
  • Cannula= a flexible tube that may be inserted into a vessel, duct, or cavity to deliver medication or drain fluid.
  • Capacitance=The ability of a dielectric material between conductors to store energy when a difference of potential exists between the conductors. The unit of measurement is the farad. Cable capacitance is usually measured in picofarads (pf).
  • Capacitive Reactance=The opposition to alternating current due to the capacitance of a capacitor, cable, or circuit. It is measured in ohms and is equal to 1/(2*pi*f*C) where pi is approximately 3.1416, f is the frequency in Hz, and C is the capacitance in farads.
  • Capacitor= A device capable of accumulating and storing an electrical charge.
  • Capacitor= Two conducting surfaces separated by a dielectric material. The capacitance is determined by the area of the surfaces, type of dielectric, and spacing between the conducting surfaces.
  • Carcinogen= a cancer-causing substance.
  • Carcinogenesis= the process of initiating and promoting cancer.
  • Carcinoma= Malignancy.
  • Carcinoma= Malignant neoplasm of epithelial cell origins.
  • Cardiac arrest= a sudden cessation of cardiac output and effective circulation. It is usually precipitated by ventricular fibrillation or ventricular asystole.
  • Cardiac tamponade= compression of the heart produced by the accumulation of blood in the pericardial sac. Also called cardiac compression.
  • Cardiac= pertaining to the heart. A cardiac patient is a person who suffers from heart disease.
  • Cardiogenic= originating in the heart muscle.
  • Cardiomegaly= Enlargement of the heart.
  • Cardiopulmonary resuscitation (CPR)= a basic emergency procedure for life support, consisting of artificial respiration and manual external cardiac massage.
  • Cardioversion= the restoration of the heart’s normal sinus rhythm through an electric shock delivered by a defibrillator.
  • C-arm tube suspension system= A type of radiography equipment that utilizes a c-shaped arm device to support the tube and the image receptor that allows the tube and image receptor to be rotated to new positions.
  • Carpal canal=Wrist passageway formed anteriorly by the flexor retinaculum, posteriorly by the capitate, laterally by the scaphoid and trapezium, and medially by the pisiform and hamate.
  • Carriage= The arm that supports the fluoroscopic equipment suspended over the table.
  • Caseation= Form of necrosis in which the tissue is changed into a dry, amorphous mass resembling cheese.
  • Cassette= a device used in radiography for holding a sheet of x-ray film and a set of intensifying screens. A cassette also may have a grid to absorb scatter radiation.
  • Cassette= rigid plastic housing for the imaging plate.
  • Catamenial= Pertaining to menstruation.
  • Cataractogenesis= the process of initiating and promoting cataracts.
  • Cathartic= a laxative preparation.
  • Catheter= a hollow, flexible tube that can be inserted into a vessel or cavity of the body to withdraw or to instill fluids, monitor various types of information, or to visualize a vessel or cavity.
  • Catheterize, catheterization= the introduction of a catheter into a body cavity or organ to inject or remove a fluid.
  • Cathode assembly= Consists of the filament, focusing cup, and associated wiring.
  • Cathode ray tube (CRT) imaging= A type of imaging that requires a film that is sensitive to the light emitted by the CRT; also called video imaging.
  • Cathode ray tube (CRT) monitor=Electronic monitor used for display and/or manipulation of the resulting digital image.
  • Cathode ray tube (CRT)= a vacuum tube that focuses a beam of electrons onto a spot on a screen coated with a phosphor, creating a visible image of information on the face of the tube. The CRT provides a means for graphically representing data processed by a computer and is often called a computer monitor.
  • Cathode The negative side of the x-ray tube; produces a thermionic cloud, conducts the high voltage to the gap between the cathode and anode, and focuses the electron stream as it heads for the anode.
  • Cathode= the negative side of the x-ray tube, which consists of the focusing cup(s) and the filament(s).
  • Caudad= Longitudinal angulation in which the tube is angled toward the patient’s feet.
  • Caudal=Foot end of the patient. A caudally angled central ray is directed toward the patient’s feet.
  • Cause-and-Effect Diagram=A causal analysis tool. Also known as a fishbone chart or Ishikawa diagram.
  • Cavitation= Formation of cavities, as in pulmonary tuberculosis or neoplasm.
  • CCU= coronary care unit or critical care unit.
  • Center of gravity= the midpoint or center of the weight of a body or object. In the standing adult human, the center of gravity is in the midpelvic cavity.
  • Center of Rotation (COR)=The fulcrum, or pivot point, of tomographic equipment motion.
  • Centesis= Puncture and aspiration.
  • Central nervous system (CNS)= Consisting of the brain and spinal cord.
  • Central nervous system (CNS)= one of the two main divisions of the nervous system, consisting of the brain and the spinal cord. The central nervous system processes information to and from the peripheral nervous system and is the main network of coordination and control for the entire body.
  • Central processing unit (CPU)= small chip found on the motherboard that manipulates data sent from a program; brains of the computer.
  • Central processing unit (CPU)= The part of the computer that directs information to and from the various components that make up the computer system.
  • Central ray (CR)= an imaginary photon in the center of the x-ray beam that is directed toward the center of the object being radiographed.
  • Central ray=Center of the x-ray beam. It is used to center the anatomic structure and IR.
  • Central Tendency=The central position of a sample frequency.
  • Central venous catheter (CVC)=Catheter used to allow infusion of substances that are too toxic for peripheral infusion, such as for chemotherapy, total parenteral nutrition, dialysis, or blood transfusions.
  • Cephalad= Longitudinal angulation in which the tube is angled toward the patient’s head.
  • Cephalic=Head end of the patient. A cephalically angled central ray is directed toward the patient’s head.
  • Cerebellum= Posterior portion of the brain located behind the brainstem.
  • Cerebrovascular accident (CVA)= an abnormal condition of the brain characterized by occlusion of an artery by an embolus or thrombus, or by cerebrovascular hemorrhage, resulting in ischemia of the brain tissues normally perfused by the damaged vessels.
  • Cerebrovascular disease= Any process that is caused by an abnormality of the blood vessels or blood supply to the brain.
  • Cerebrum= Left and right larger superior portion of the brain.
  • Cervical rib= An extra rib that articulates with a cervical vertebra.
  • Cesium iodide scintillator (Csi)= newer type of amorphous silicon detector that uses a cesium iodide (Csi) scintillator; the scintillator is made by growing very thin crystalline needles (5μm wide) that work as light-directing tubes, much like fiberoptics.
  • Cesium-137 (Cs-137)= has a half-life of 30.17 years and decays by beta and gamma radiation. Cs-137 is produced by nuclear fission for use in medical devices and gauges and is one of the byproducts of nuclear fission processes in nuclear reactors and nuclear weapons testing. Small quantities of Cs-137 can be found in the environment from nuclear weapons tests that occurred in the 1950s and 1960s and from nuclear reactor accidents, such as the Chernobyl power plant accident in 1986, which distributed Cs-137 to many countries in Europe.
  • Chain reaction= a process that initiates its own repetition. In a fission chain reaction, a fissile nucleus absorbs a neutron and fissions (splits) spontaneously, releasing additional neutrons. These, in turn, can be absorbed by other fissile nuclei, releasing still more neutrons. A fission chain reaction is self-sustaining when the number of neutrons released in a given time equals or exceeds the number of neutrons lost by absorption in non-fissile material or by escape from the system.
  • Channeling=A potential problem in certain metallic replacement silver recovery units whereby the fixer forms a straight channel that reduces efficiency.
  • Characteristic cascade= The reaction of electrons dropping into the holes created during a characteristic interaction until there is only a hole in the outer shell.
  • Characteristic curve= A radiographic relationship between the amount of exposure and the resultant density on the film; also known as D log E curve, sensitometric curve, and Hurter and Driffield curve.
  • Characteristic Impedance= In a transmission cable of infinite length, the ratio of the applied voltage to the resultant current at the point the voltage is applied. Or the impedance which makes a transmission cable seem infinitely long, when connected across the cable’s output terminals.
  • Characteristic interaction= The incident electron interacts with an inner shell electron, knocking out the inner shell electron and continuing in a slightly different direction, which creates a hole in the inner shell, making the shell unstable.
  • Characteristic peak= Occurs when K-shell emissions reach their effective energy range of 69 kev.
  • Characteristic photon An x-ray photon created by the electron transfer from one shell to another.
  • Charge-coupled device (CCD)= coupling devices that act as cameras that link phosphor signals to a signal.
  • Charge-Coupled Device (CCD)=A two-dimensional electronic array for converting light patterns into electronic signals.
  • Chart, charting= a patient’s medical record; to note data in a patient record, usually at prescribed intervals.
  • Chatter=Artifact that appears as bands of increased optical density that occur perpendicular to film direction because of inconsistent motion of the transport system, usually the result of slippage of the drive gears of drive chain.
  • Chemical Activity=How well the processing solutions per-form their desired function.
  • Chemical energy The form of energy released during a chemical reaction.
  • Chemical fog= The effect on a film when unexposed silver halides are reduced.
  • Chemical Impurity=The presence of a chemical or other substance that normally should not be present.
  • Chemical precipitation= A type of silver recovery system that uses chemicals to break down in the fixer and release electrons; the silver is heavy and falls to the bottom of the tank.
  • Chemotherapy= the treatment of infections and other diseases with chemical agents. In modern usage, chemotherapy entails the use of chemicals to destroy cancer cells on a selective basis, usually resulting in immunosuppression.
  • Chest physiotherapy= Chest percussions (tapping) to keep lung secretions moving.
  • Chi-Square=A statistic test for an association between observed data and expected data represented by frequencies.
  • Cholangiogram, cholangiography= image/examination of the biliary ducts after injection of a radiopaque contrast medium. It is usually performed before or after biliary tract surgery, and may be part of the surgical procedure.
  • Cholecystectomy= the surgical removal of the gallbladder.
  • Cholecystitis= inflammation of the gallbladder.
  • Cholecystogram, cholecystography= an x-ray image/ examination of the gallbladder, made after the ingestion or injection of a radiopaque substance, usually a contrast material containing iodine.
  • Cholera= an acute bacterial infection of the small intestine, characterized by severe diarrhea and vomiting, muscular cramps, dehydration, and depletion of electrolytes. The disease is spread by water and food that have been contaminated by feces of persons previously infected.
  • Chondroblastic= Forming cartilaginous tissue.
  • Chondrosarcoma= Malignant tumor of cartilaginous origin.
  • Chordae tendineae= Thin cords that connect each cusp of the two atrioventricular valves to papillary muscles in the heart ventricles.
  • Chorion= Important fetal membrane for exchange of nutrients.
  • Choroid plexus= Tangled mass of fine blood vessels within the ventricles producing cerebrospinal fluid.
  • Chromatography=Any one of several processes for separating and analyzing various gaseous or dissolved chemical materials.
  • Chromophobe adenomas= Pituitary tumor of nonstaining cells (acid or basic dyes).
  • Chronic atrophic gastritis= Severe mucosal wasting that causes thinning and a relative absence of mucosal folds in the stomach.
  • Chronic bronchitis= Excessive tracheobronchial mucus production leading to the obstruction of small airways.
  • Chronic exposure= exposure to a substance over a long period of time, possibly resulting in adverse health effects.
  • Chronic obstructive pulmonary disease (COPD)= a progressive and irreversible condition characterized by diminished inspiratory and expiratory capacity of the lungs.
  • Chronic osteomyelitis= New bone growth at the site of a chronic bone infection:
  • Chronic= developing slowly and persisting for a long period.
  • Chyme= Gastric contents that have become mixed with hydrochloric acid and the proteolytic enzyme pepsin, resulting in a milky white product.
  • Cilia (singular, cilium)= small, hairlike processes on the outer surfaces of some cells, aiding metabolism by producing motion, eddies, or current in a fluid.
  • Cinefluorography=The recording of a fluoroscopic image onto motion picture film.
  • Circuit breaker= A device constructed to interrupt a circuit before a dangerous temperature is reached.
  • Circuit=A system of conducting media designed to pass an electric current.
  • Circulating nurse= an assistant to the scrub nurse and surgeon whose role is to provide necessary supplies, dispose of soiled supplies, and to keep an accurate count of instruments, needles, and sponges.
  • Circulation system= A part of the automatic processing system designed to stabilize temperatures, agitate solutions, mix the chemistry, and filter the solutions.
  • Cirrhosis= Fibrotic changes in the liver causing the liver to enlarge and ascites to develop.
  • Claustrophobia, claustrophobic= a morbid fear of being in or becoming trapped in enclosed or narrow places.
  • Clearing agent= The primary agent of the fixer.
  • Clearing time= Twice the time necessary for the milky appearance of the film to disappear.
  • Client/server-based system= PACS workflow where the images are sent directly to the archive server after acquisition and are centrally located
  • Client-based network= similar to a server-based network, in that there is a centralized computer that controls the operations of the network, but rather than sending the entire original resource to the client for processing, the server processes the resource as requested by the client and returns only the results back to the client.
  • Closed fracture= Fracture that does not disrupt the skin.
  • Closed-core transformer= Arrangement of two coils of wire each filled with an iron core in proximity to facilitate induction that converges the inside and outside lines of force through the core.
  • CNS= central nervous system.
  • Coagulation factors= Responsible for the process of blood clotting.
  • Coalesce= To merge into a single mass.
  • Coating= The phase of the film production process in which the adhesive layer is applied to the base, then the emulsion and, finally, the supercoat.
  • Coaxial cable= network communication medium that is similar to TV cable wiring.
  • Cobalt (Co)= a gray, hard, magnetic, and somewhat malleable metal. Cobalt is relatively rare and generally obtained as a byproduct of the production of other metals, such as copper. Its most common radioisotope, cobalt-60 (Co-60), is used in radiography and medical applications. Co-60 emits beta particles and gamma rays during radioactive decay.
  • Coccidioidomycosis= an infectious fungal disease caused by the inhalation of spores of the bacterium Coccidioides immitis, which is carried on windborne dust particles.
  • Coccus (plural, cocci)= a bacterium that is round, spherical, or oval, as gonococcus, pneumococcus, staphylococcus, streptococcus.
  • Code team= a specially trained and equipped team that is available to provide cardiopulmonary resuscitation when summoned by a specific code over the public address system. A code team usually includes a physician, one or more registered nurses, respiratory therapist, and pharmacist.
  • Code= a discreet signal used to summon an emergency response team to resuscitate a patient without alarming patients or visitors, as in “Code zero, 3 west” announced over a public address system to summon the team to the west wing of the third floor.
  • Coercivity = measure of how permanent a magnet is; permanent magnets have a high coercivity. The intensity of a magnetic field needed to demagnetize a substance.
  • Coercivity= The energy that caused reorientation of the magnetic dipoles.
  • Coeur en sabot= Appearance resembling the curved-toe portion of a wooden shoe.
  • Coherent scatter= An interaction between x-rays and matter characterized by interaction between a very low-energy x-ray photon and matter causing the electron to vibrate at the same frequency as the incident photon, which then produces a secondary photon with the same energy and wavelength as the incident photon but which travels in a different direction; also called classical scatter or unmodified scatter.
  • Coil Effect=The inductive effect exhibited by a spiral=wrapped shield, especially above audio frequencies.
  • Colic= Intermittent abdominal pain whose fluctuation corresponds to smooth muscle peristalsis.
  • Collaterals= Blood vessels that develop or enlarge to provide an alternative route around an obstruction.
  • Collecting tubule= Funnels urine into the papillary ducts in the renal pelvis.
  • Collective dose= (Animation) The sum of the individual doses received in a given time period by a specified population from exposure to a specified source of radiation.
  • Colles’ fracture= Transverse fracture of the distal radial metaphysis proximal to the wrist with a dorsal displacement of the distal fragment.
  • Collimater pitch= The pitch of a single detector within a MDCT array of image receptors.
  • Collimation= type of wire that consists of a center wire surrounded by insulation and then a grounded shield of braided wire; the shield minimizes electrical and radio frequency interference.
  • Collimator= a device for limiting the size and shape of an x-ray beam.
  • Collimator= A set of lead shutters at right angles to one another which move in opposing pairs.
  • Collimator= Containing multiple parallel channels to allow the rays to pass.
  • Collimator=(1) A device that regulates the area of x-ray beam exposure. (2) A device for improving image resolution in nuclear medicine procedures.
  • Color layer= area within the conductive layer where electrons are trapped.
  • Colostomy= surgical creation of an artificial anus (stoma) on the abdominal wall by incising the colon and drawing it out to the surface.
  • Coma, comatose= pertaining to a state of abnormally deep sleep, caused by illness or injury.
  • Combined injury= physical, thermal, and/or chemical trauma combined with radiation exposure at a dose sufficient to diminish the likelihood of overall survival or functional recovery.
  • Comminuted fracture= Composed of more than two fragments.
  • Committed dose equivalent (CDE)= The dose to a specific organ or tissue that is received from an intake of radioactive material by an individual over a specified time after the intake. For radiation protection purposes, the specified time is to the age of 70, which is normally taken to be 50 years for a radiation worker and 70 years for a member of the public.
  • Committed dose= a dose that accounts for continuing exposures expected to be received over a long period of time (such as 30, 50, or 70 years) from radioactive materials that were deposited inside the body.
  • Committed effective dose equivalent (CEDE)= The committed dose equivalent for a given organ multiplied by a weighting factor .
  • Commode= a toilet.
  • Communicating hydrocephalus= Increased cerebrospinal fluid involving the entire ventricular system and subarchnoid space.
  • Community acquired= Infected by exposure in the public domain.
  • Commutator ring= A single ring that is divided in half, with each half connected to one end of the armature wire.
  • Compact bone= Outer layer that to the naked eye appears dense and structureless.
  • Comparator=A portion of an automatic exposure control system that compares the amount of radiation detected with a preset value.
  • Compensating filter= Used to even out unequal densities.
  • Compensating filter=Absorbing substance added in the path of the x-ray beam that will remove photons from the beam. The filter is used to even out the density of structures that are imaged at the same time and vary in part thickness, such as the femur or lower leg.
  • Complementary metal oxide semiconductor (CMOS)= special type of memory chip that uses a small rechargeable or lithium battery to retain information about the pc’s hardware while the computer is turned off.
  • Complete fracture= Discontinuity between two or more fragments.
  • Compound filter= The use of two or more materials to complement one another in their absorbing abilities; also known as K-edge filters.
  • Compound fracture= Overlying skin is disrupted with tissue destruction.
  • Compound= A complex substance; two or more elements that are chemically united in a definite proportion.
  • Compression band= A piece of equipment used to restrain a patient or compress abdominal tissue.
  • Compression fracture= Compaction of bone trabeculae and results in decreased bone length or width.
  • Compression=Applying pressure to a body area to reduce part thickness.
  • Compton effect= An interaction between x-rays and matter characterized by an incident x-ray photon interacting with a loosely bound outer-shell electron, resulting in removal of the electron from the shell, which then proceeds in a different direction as a scattered photon; also known as Compton scattering.
  • Compton electron= The dislodged electron resulting from Compton scattering; also called a recoil electron.
  • Compton scattered photon= The photon that exits the atom in a different direction as a result of Compton scattering.
  • Compton scattering= An interaction between x-rays and matter characterized by an incident x-ray photon interacting with a loosely bound outer-shell electron, resulting in removal of the electron from the shell, which then proceeds in a different direction as a scattered photon; also known as Compton effect.
  • Computed radiography (CR)= A type of indirect digital radiography; the radiographer must move the detector between image acquisition and display.
  • Computed radiography (CR)= or cassette-based digital radiography is the digital acquisition modality that uses storage phosphor plates to produce projection images.
  • Computed radiography (CR)= the method of using a digital computer to record radiographic images and to project them onto a video monitor.
  • Computed Radiography (CR)=A process of creating a digitized radiographic image using a photostimulable phosphor.
  • Computed radiography=Projection radiography that uses photostimulable phosphor plates (imaging plates) as the IR.
  • Computed tomography (CT)= a computerized radiographic technique that produces a detailed image of a cross section of an anatomic structure.
  • Computed tomography unit= Specialized radiography equipment that allows the taking of sectional images.
  • Computed tomography= Produces cross-sectional tomographic images by first scanning a slice of tissue from multiple angles with a narrow x-ray beam.
  • Computer= programmable electronic device that can store, retrieve, and process data.
  • Concave=Curved or rounded inward. The anterior surface of the metacarpals is concave.
  • Concentration= Law of electrostatics that states the greatest intensity of charge will be on the surface where the curvature is the sharpest.
  • Concentration= the ratio of the amount of a specific substance in a given volume or mass of solution to the mass or volume of solvent.
  • Concurrent Data=Data collected during the time of care.
  • Concussion= damage to the brain caused by a violent jarring or shaking, such as a blow or an explosion.
  • Conductance= The measure of resistance in a DC current when the expression 1/R is used.
  • Conduction band= An area within the force field of an atom beyond the valence band.
  • Conductive layer= layer of material that will absorb and reduce static electricity.
  • Conductivity=The ability of a material to allow electrons to flow, measured by the current per unit of voltage applied. It is the reciprocal of resistivity and is measured in siemens (S) or mhos.
  • Conductor= A material that allows electrons to flow freely.
  • Condyle=Rounded projection on a bone that often articulates with another bone.
  • Cone cell= Cells in the retina of the eye that are responsible for color vision.
  • Cone= A circular aperture diaphragm with metal extensions that flare or diverge with the upper diameter smaller than the bottom flared end.
  • Conference of Radiation Control Program Directors (CRCPD)= an organization whose members represent state radiation protection programs.
  • Congenital megacolon= also called Hirschsprung’s disease, the absence at birth of autonomic ganglia in the smooth muscle wall of the colon, which causes poor or absent peristalsis in the involved segment of the colon, accumulation of feces, and dilation of the bowel.
  • Congenital= Existing at birth.
  • Congenital= present at birth, as a congenital anomaly or defect.
  • Congestive heart failure (CHF)= an abnormal condition that reflects impaired cardiac pumping. It is caused by myocardial infarction, ischemic heart disease, or cardiomyopathy.
  • Congestive heart failure= Increased venous congestion in the heart resulting from diminished cardiac output.
  • Conjunctiva (plural, conjunctivae)= the mucous membrane lining the inner surfaces of the eyelids and anterior part of the sclera.
  • Conjunctivitis= Inflammation of the delicate membrane that lines the eyelids and covers the exposed surface of the sclera (white part) of the eye.
  • Connect the elements of the assembly together.
  • Constipation= Extra water is absorbed from the fecal mass to produce a hardened stool.
  • Consumer=An individual who chooses to comment or complain in reference to an examination including the patient or representative of the patient (e.g., family member or referring physician).
  • Contact surgical radiography= A type of imaging which uses nonscreen film in sterilized packages.
  • Contaminate, contamination= to soil, stain, touch, or otherwise expose to harmful agents, making an object potentially unsafe for use as intended or without barrier techniques.
  • Contamination (radioactive)= the deposition of unwanted radioactive material on the surfaces of structures, areas, objects, or people where it may be external or internal.
  • Contamination means that radioactive materials in the form of gases, liquids, or solids are released into the environment and contaminate people externally, internally, or both. An external surface of the body, such as the skin, can become contaminated, and if radioactive materials get inside the body through the lungs, gut, or wounds, the contaminant can become deposited internally.
  • Contamination, fixed= Fixed skin contamination is that which remains after bathing or attempted decontamination. Contamination is assumed to be removed by natural processes within 336 hours (14 days) after deposition on the skin.
  • Contamination, loose= Loose skin contamination is that which is removable by bathing or decontamination.
  • Continuity of Care=The degree to which the care is coordinated among practitioners or organizations, or both.
  • Continuous quality improvement (CQI)= alternative set of terms for total quality management that includes maintenance of equipment, image acquisition, and processing standards.
  • Continuous Variables=Variables that have an infinite range of mathematic values.
  • Contracture= Shortening or shrinkage of a muscle or tendon resulting in persistent flexion or distortion at a joint.
  • Contraindication= the presence of a disease or physical condition that makes it impossible or undesirable to treat a particular client in the usual manner or to prescribe medicines that might otherwise be suitable.
  • Contrast Indicator=Value obtained during sensitometric testing, which indicates film contrast.
  • Contrast manipulation= conversion of the digital image using contrast enhancement parameters.
  • Contrast mask= A tool to help focus on contrast in a selected area.
  • Contrast media injection device= Type of instrument that is used to inject contrast
  • Contrast medium (plural, contrast media), contrast agent= a gas or radiopaque substance that is injected into the body, introduced via catheter, or swallowed in order to facilitate radiographic imaging of internal structures that otherwise are difficult to visualize radiographically.
  • Contrast perception= The ability to visually distinguish differences in density or contrast.
  • Contrast resolution=Ability of an imaging system to resolve low-contrast objects on an image.
  • Contrast Resolution=The ability of an imaging system to distinguish structures with similar transmission as separate entities.
  • Contrast Scale=The change in linear attenuation coefficient per computed tomographic number relative to water.
  • Contrast= One of the properties that comprise visibility of detail; the difference between adjacent densities.
  • Contrast=Number of shades of gray that represent the different structures on the image.
  • Contrast-to-Noise Ratio (CNR)=The ratio between the image contrast to the amount of image noise (both quantum mottle and/or electronic); can be used to describe image quality.
  • Contributory negligence= an act of negligence in which the behavior of the injured party contributed to the injury.
  • Control Chart=A modification of the trend chart in which statistically determined upper and lower control limits are placed.
  • Controlled area= An area where entry, activities, and exit are controlled to help ensure radiation protection and prevent the spread of contamination.
  • Controlled substance= any drug defined in the five categories of the federal Controlled Substances Act of 1970. The categories, or schedules, cover opium and its derivatives, hallucinogens, depressants, and stimulants.
  • Contusion= an injury that does not disrupt the integrity of the skin, caused by a blow to the body and characterized by swelling, discoloration, and pain. Also called a bruise.
  • Conversion efficiency= The ability of the phosphor to emit as much light per x-ray photon interaction as possible which is related to the screen speed.
  • Convex=Curved or rounded outward. The posterior surface of the metacarpals is convex.
  • Convolution= The process of modifying pixel values by a mathematical formula; also referred to as mask.
  • Convulsion= the hyperexcitation of neurons in the brain that leads to a sudden, involuntary series of contractions of a group of muscles. Also called a seizure.
  • COPD= chronic obstructive pulmonary disease.
  • Corona=The ionization of gasses about a conductor that results when the potential gradient reaches a certain value.
  • Coronal plane=Imaginary plane that passes through the body from side to side and divides it into two (not necessarily equal) sections, one anterior and one posterior.
  • Coronary= pertaining to encircling structures, such as the coronary arteries; pertaining to the heart.
  • Corporate negligence= negligence attributable to a hospital or other corporation as an entity.
  • Corpus callosum= Mass of white matter connecting the two cerebral hemispheres.
  • Corpus luteum= Anatomic structure on the ovary surface.
  • Corrosive gastritis= Inflammation of the stomach caused by corrosive agents.
  • Cortex= Outer portion of a bone or internal organ (kidney, adrenal gland, brain).
  • Cortical outline=Outer layer of a bone demonstrated on an image as the white outline of an anatomic structure.
  • Corticosteroid= any one of the natural or synthetic hormones elaborated by the adrenal cortex (excluding the sex hormones of adrenal origin) that influence or control key processes of the body. A corticosteroid may be prescribed as an antiallergic medication.
  • Cortisone= a glucocorticoid produced in the liver and made synthetically. It may be prescribed as an antiinflammatory.
  • Cosmic radiation= radiation produced in outer space when heavy particles (nuclei of all known natural elements) bombard the earth.
  • Costal breathing=Slow shallow breathing; used with a long exposure time to blur chest details.
  • Costal= pertaining to one or more ribs; situated near a rib or on a side close to a rib. Costal respirations involve movement of the rib cage.
  • Coulomb per kilogram= A radiographically derived unit of the SI system, abbreviated as C/kg, formerly known as the roentgen.
  • Coulomb per Kilogram=International System of Units radiation intensity equivalent to 3876 roentgens.
  • Coulomb= the international system (SI) unit of electric charge. A coulomb is the quantity of charge passing a cross section of conductor in one second when the current is one ampere.
  • Count Rate=Measurement of the activity of a radioactive substance.
  • Counts per Minute=A measure of the decay rate of ionizing emissions by radioactive substances.
  • Coupling=The transfer of energy (without direct electrical contact) between two or more cables or components of a circuit.
  • Creatinine= a substance formed from the metabolism of creatine, commonly found in blood, urine, and muscle tissue. It is measured in blood and urine tests as an indicator of kidney function.
  • Creutzfeldt–Jakob disease= the human variant of mad cow disease. A rare fatal condition of the structure and function of brain tissues caused by an unidentified slow virus or prion.
  • Criss-cross grid= Two linear grids placed on top of one another so that the lead strips form a criss­cross pattern.
  • Critical mass= the minimum amount of fissile material that can achieve a self-sustaining nuclear chain reaction.
  • Critical Path=Documents the basic treatment or action sequence in an effort to eliminate unnecessary variation.
  • Criticality= a fission process where the neutron production rate equals the neutron loss rate to absorption or leakage. A nuclear reactor is “critical” when it is operating.
  • Crossed ectopic= Ectopic kidney located on the same side as the normal kidney.
  • Cross-hatched grid= Two linear grids placed on top of one another so that the lead strips form a criss-cross pattern.
  • Crossover effect= Blurring of the image caused by light from one screen crossing into the light from another screen.
  • Crossover network= Part of the automatic processing transport system designed to bend and turn the film when it reaches the top of the transport rack and must be directed down to the next tank or section.
  • CRT= abbreviation for cathode ray tube, a computer monitor.
  • Cryogen= Cooling agent.
  • Crystal production= The part of the film manufacturing process that must be done in total darkness Silver nitrate and potassium bromide are combined in the presence of gelatin; the silver bromide precipitates out and the potassium nitrate can be washed away as a waste product.
  • CT number= Attenuation of a specific tissue relative to that of water.
  • CT= abbreviation for computed tomography.
  • Cumulative dose= the total dose resulting from repeated or continuous exposures of the same portion of the body, or of the whole body, to ionizing radiation.
  • Curie (Ci)= the traditional measure of radioactivity based on the observed decay rate of 1 gram of radium. One curie of radioactive material will have 37 billion disintegrations in 1 second.
  • Curie (CI)= The unit of activity.
  • Curie point = temperature above which a magnetic material will lose its magnetism. Discovered by the french scientist pierre curie in the 1890s.
  • Current Carrying Capacity=The maximum current a conductor can carry without being heated beyond a safe limit. Ampacity.
  • Current to produce mechanical motion.
  • Current, Alternating (ac)=Electric current that alternates or reverses polarity in a cyclical manner (e.g. 60 Hertz AC power).
  • Current, Direct (dc)=Electrical current whose electrons flow in one direction only and is generally constant.
  • Current= The quantity or the number of electrons flowing.
  • Curvilinear= Having a curved configuration.
  • Customer=A person, department, or organization that needs or wants the desired outcome.
  • Cutaneous Radiation Syndrome (CRS)= the complex syndrome resulting from radiation exposure of more than 200 rads to the skin. The immediate effects can be reddening and swelling of the exposed area (like a severe burn), blisters, ulcers on the skin, hair loss, and severe pain. Very large doses can result in permanent hair loss, scarring, altered skin color, deterioration of the affected body part, and death of the affected tissue (requiring surgery).
  • CVA= abbreviation for cerebrovascular accident. See stroke.
  • Cyanosis, cyanotic= bluish discoloration of the skin and mucous membranes caused by an excess of deoxygenated hemoglobin in the blood or a structural defect in the hemoglobin molecule.
  • Cylinder= A circular aperture diaphragm with metal extensions that have the same diameter at the top and bottom.
  • Cyst, cystic= pertaining to a cyst, a fluid-filled sac.
  • Cyst= Saclike structure usually filled with fluid.
  • Cystadenoma= Benign tumor forming a large cystic mass.
  • Cytology= Microscopic examination to determine cell structure.
  • Cytomegalovirus= a member of a group of large, species-specific herpes-type viruses with a wide variety of disease effects. It causes serious illness in persons with human immunodeficiency virus, in newborns, and in people being treated with immunosuppressive drugs and therapy, especially after organ transplantation.
  • D log E curve= A radiographic relationship between the amount of exposure and the resultant density on the film; also known as characteristic curve, sensitometric curve, and Hurter and Driffield curve.
  • D max= The maximum density the film is capable of recording.
  • Dacryocystography= radiography of the lacrimal drainage system, the passage from the tear duct to the nasopharynx.
  • Darkroom=Area protected from white light where films are processed.
  • Data Set=The information or measurements that were acquired by evaluating the particular sample.
  • Data= Collected facts.
  • Daylight System=A system for loading and unloading film from image receptors outside of a darkroom.
  • De novo= From the beginning; anew.
  • Debilitated= feeble, weak, or otherwise disabled.
  • Decay chain (decay series)= the series of decays that certain radioisotopes go through before reaching a stable form. For example, the decay chain that begins with uranium-238 (U-238) ends in lead-206 (Pb-206) after forming isotopes, such as uranium-234 (U-234), thorium-230 (Th-230), radium-226 (Ra-226), and radon-222 (Rn-222).
  • Decay constant= the fraction of a number of atoms of a radionuclide that disintegrates in a unit of time. The decay constant is inversely proportional to the radioactive half-life.
  • Decay products (or daughter products)= the isotopes or elements formed and the particles and high-energy electromagnetic radiation emitted by the nuclei of radionuclides during radioactive decay. Also known as “decay chain products” or “progeny” (the isotopes and elements). A decay product may be either radioactive or stable.
  • Decay, radioactive= disintegration of the nucleus of an unstable atom by the release of radiation.
  • Decibel (db)=A decibel is one=tenth of a bel and is equal to 10 times the logarithm of the power ratio, 20 times the log of the voltage ratio, or 20 times the log of the current ratio. Decibels are also used to express acoustic power, such as the apparent level of a sound. The decibel can express an actual level only when comparing with some definite reference level that is assumed to be zero db.
  • Declination = measure of the angle between the magnetic north or south pole and the geographic north or south pole.
  • Decompression= the removal of pressure caused by gas or fluid in a body cavity, as the stomach or intestinal tract.
  • Decontamination (radioactive)= the reduction or removal of radioactive contamination from a structure, object, or person.
  • Deconvolution= The process of returning the pixel values to their original level by a reverse process.
  • Decorporation= removal of radioactive isotopes from the body using specific drugs called “decorporation agents.”
  • Decubitus ulcers= lesions that develop over bony prominences when pressure is exerted for any length of time. Also called bedsores.
  • Decubitus=Refers to the patient lying down on a table or cart while a horizontally directed central ray is used; also used with the term decubitus is the surface (lateral, dorsal, or ventral) placed adjacent to the table or cart. The patient is in a left lateral decubitus position.
  • Defecate, defecation= the elimination of feces from the digestive tract through the rectum.
  • Defecography= an imaging procedure for the evaluation of patients with defecational dysfunction, also known as evacuation proctography or dynamic rectal examination.
  • Defendant= the party named in a plaintiff’s complaint and against whom the plaintiff’s allegations are made.
  • Defibrillate, defibrillation= to terminate ventricular fibrillation by delivery of an electrical shock to the patient’s chest.
  • Defibrillator= a device that delivers an electrical shock at a preset voltage to the myocardium through the chest wall for the purpose of restoring normal heart rhythm.
  • Deficit Reduction Act=Federal legislation enacted in 2005 to help reduce Medicare and Medicaid spending.
  • Definition= One of the geometric properties of image quality; the degree of geometric sharpness or accuracy of structural lines actually recorded in the image; also referred to as detail, recorded detail, sharpness, spatial resolution.
  • Degenerative arthritis= Inflammation of the joints resulting in destruction of adjoining joint tissue.
  • Degenerative= pertaining to or involving degeneration or change to a lower or dysfunctional form.
  • Deglutition= Swallowing.
  • Dehiscence= the separation of a surgical incision or rupture of a wound closure, typically an abdominal incision.
  • Dehydrate, dehydration= to remove or lose water from a substance. Dehydration of the body is accompanied by a disturbance in the balance of essential electrolytes, particularly sodium, potassium, and chloride.
  • Delay Line=A transmission line or equivalent device designed to delay a wave or signal for a specific length of time.
  • Demarcate= To set or mark the limits of.
  • Dengue fever= an acute arbovirus infection transmitted to humans by the Aedes mosquito and occurring in tropic and subtropic regions.
  • Densitometer= An instrument that provides a readout of the amount of blackening (density) on a film.
  • Densitometer=Electronic device for measuring the optical density of a film.
  • Density= One of the photographic properties that comprise visibility of detail; the degree of overall blackening of the film.
  • Density=Degree of darkness on an image.
  • Depleted uranium= uranium containing less than 0.7% uranium-235, the amount found in natural uranium.
  • Deposition density= the activity of a radionuclide per unit area of ground. Reported as becquerels per square meter or curies per square meter.
  • Depress=To lower or sink down, positioning at a lower level.
  • Depressed skull fracture= Comminuted fracture in which fragments are driven inward.
  • Depth of Visualization=Depth into a patient or phantom at which signals from scattered echoes can create an image.
  • Derating Factor=A multiplier used to reduce the current carrying capacity of conductors in more adverse environments, such as higher temperature, or where multiple conductors are together in one conduit.
  • Dermatitis= an inflammatory condition of the skin. Various cutaneous eruptions occur and may be unique to a particular allergen, disease, or infection.
  • Destructive condition= A disease that causes body tissues to thin, decrease in atomic number, or decrease in density, requiring a decrease in technical factors to achieve proper image receptor exposure.
  • Destructive disease=Condition that results in change to the normal bony structures, soft tissues, or air or fluid content of the patient; may require technical changes to compensate for them prior to exposing the patient. Destructive diseases cause the tissues to decrease mass density or thickness, resulting in them being more radiolucent.
  • Detail extremity radiography= A type of imaging that uses fine-grain films with slow-speed screens.
  • Detail= One of the geometric properties of image quality; the degree of geometric sharpness or accuracy of structural lines actually recorded in the image; also referred to as recorded detail, definition, sharpness, spatial resolution.
  • Detail=Part of the whole structure. The trabeculae are details in the femoral bone.
  • Detective quantum efficiency (DQE)= measurement of how efficiently a system converts x-ray input signal into a useful output image.
  • Detector size= actual physical size, length and width, of the x-ray detector.
  • Detector= A device that is sensitive to radiation and can produce a response signal suitable for measurement or analysis. A radiation detection instrument.
  • Detector=Also known as the sensor, it is a radiation detector that monitors the radiation exposure at or near the patient and produces a corresponding electric current that is proportional to the quantity of x-rays detected.
  • Detent= a mechanism that tends to stop a moving part in a specific location. Detents are built into x-ray tube supports to facilitate tube placement at standard locations.
  • Deterministic effect= an effect that can be related directly to the radiation dose received. The severity increases as the dose increases. A deterministic effect typically has a threshold below which the effect will not occur.
  • Deterministic effect= Results of radiation exposure for which a threshold dose of radiation is assumed (e.g., cataracts, sterility).
  • Deuterium= a non-radioactive isotope of the hydrogen atom that contains a neutron in its nucleus in addition to the one proton normally seen in hydrogen. A deuterium atom is twice as heavy as normal hydrogen.
  • Developer=A processing solution responsible for conversion of the latent image to a manifest image in film.
  • Developing= The step in film processing; silver is deposited at the latent image sites and an image becomes visible.
  • Deviate=To move away from the normal or routine.
  • Diabetes, diabetic= clinical condition characterized by the excessive excretion of urine. The excess may be caused by a deficiency of antidiuretic hormone (ADH), as in diabetes insipidus, or it may be the polyuria resulting from the hyperglycemia that occurs in diabetes mellitus.
  • Diabetic coma= a life-threatening condition occurring in persons with diabetes mellitus. It is caused by inadequate treatment, failure to take prescribed insulin, excessive food intake, or, most frequently, infection, surgery, trauma, or other stressors that increase the body’s need for insulin.
  • Diagnosis, diagnostic= identification of a disease or condition by a scientific evaluation of physical signs, symptoms, history, laboratory test results, and procedures.
  • Diagnostic specifier=In computed radiography, examination indicator chosen by technologist before the plate is processed. It tells you the anatomic structure, position, and projection under which the image plate is to be processed.
  • Diagnostic= Methods used to determine the source or cause of a disease, disorder, or traumatic injury.
  • Dialysis= a medical procedure for the removal of certain substances from the blood or lymph by virtue of the difference in their rates of diffusion through an external semipermeable membrane or, in the case of peritoneal dialysis, through the peritoneum. Dialysis is a treatment for chronic kidney failure.
  • Diamagnetic Materials weakly repelled by all magnetic fields (e.g., beryllium, bismuth, lead).
  • Diaphoresis, diaphoretic= the secretion of sweat, especially the profuse secretion associated with an elevated body temperature, physical exertion, exposure to heat, and mental or emotional stress.
  • Diaphysis= Shaft of a long bone.
  • Diarrhea= Results from increased motility of the small bowel, which floods the colon with an excessive amount of water that cannot be completely absorbed.
  • Diastatic fracture= Linear fracture intersecting a suture and coursing along it to cause sutural separation.
  • Diastole, diastolic= pertaining to diastole, the blood pressure at the instant of maximum cardiac relaxation.
  • Diastole= Heart relaxation phase when blood enters the heart.
  • Dichotomous Variables=Variables that have only two values or choices.
  • Dicom= digital imaging and communications in medicine; it is a global information technology standard that allows network communication between modality and PACS.
  • DICOM=Digital Imaging and Communications in Medicine, a standard used for transferring digital images in diagnostic imaging.
  • Dielectric Breakdown=Any change in the properties of a dielectric that causes it to become conductive. Normally a catastrophic failure of an insulation because of excessive voltage.
  • Dielectric Constant=Also called relative permittivity. That property of a dielectric which determines the amount of electrostatic energy that can be stored by the material when a given voltage is applied to it. Actually, the ratio of the capacitance of a capacitor using the dielectric to the capacitance of an identical capacitor using a vacuum (which has a dielectric constant of 1) as a dielectric. A number which indicates the quality of a material to resist holding an electrical charge when placed between two conductors.
  • Dielectric Heating=The heating of an insulating material when placed in a radio=frequency field, caused by internal losses during the rapid polarization reversal of molecules in the material.
  • Dielectric Loss=The power dissipated in a dielectric as the result of the friction produced by molecular motion when an alternating electric field is applied.
  • Dielectric Strength=The voltage an insulation can withstand before it breaks down. Usually expressed as “volts per mil”.
  • Dielectric Withstand Voltage=The voltage an insulation can withstand before it breaks down. Usually expressed as “volts per mil”.
  • Dielectric= The insulation between two plates in a capacitor.
  • Dielectric=An insulating (non=conducting) medium. It is the insulating material between conductors carrying a signal in a cable. In coaxial cables it is between the center conductor and the outer conductor. In twisted pair cables it is the insulation between conductors plus any surrounding air or other material.
  • Diencephalon= Lies between the cerebrum and the midbrain and consists of the third ventricle, thalamus, and hypothalamus.
  • Differential absorption=Radiographic contrast caused by the atomic density, atomic number, and thickness composition differences of the patient’s body parts and how differently each tissue composition will absorb x-ray photons.
  • Differentiation= a process in development in which unspecialized cells or tissues are systemically modified and altered to achieve specific and characteristic physical forms, physiological functions, and chemical properties.
  • Diffusion imaging= Relies on the movement of molecules and random thermal motion.
  • Digital angiography= Produces one image similar to the last fluoroscopy hold vascular image; also called spot imaging.
  • Digital cineradiography= Takes numerous exposures (frames) in a second of time.
  • Digital computer= A unit that processes data composed of discrete quantities of current.
  • Digital Fluoroscopy=Computerized enhancement of fluoroscopic images.
  • Digital Imaging and Communications in Medicine (DICOM)=A system of computer software standards that allows different digital imaging programs to understand one another.
  • Digital imaging= any imaging acquisition process that produces an electronic image that can be viewed and manipulated on a computer.
  • Digital mammography unit= A dedicated breast imaging machine that utilizes a CR/DR image receptor system.
  • Digital radiography (DR)= or cassette-less systems use an x-ray absorber material coupled to a flat panel detector or a charged-coupled device to form the image.
  • Digital Radiography (DR)=A method of obtaining a digitized radiographic image utilizing an active matrix array.
  • Digital radiography (DR)=System that uses detectors to convert x-ray energy to electrical energy that is delivered directly to a computer, where the anatomic image is digitally processed and displayed.
  • Digital subtraction angiography= Eliminates bone and soft tissue structures from an image so that only the contrast-filled vessels remain.
  • Digital Subtraction Angiography=An electronic method of enhancing visibility of vascular structures involving digital fluoroscopy.
  • Digital tomosynthesis= Digital radiographic tomography.
  • Digital versatile disk (DVD)= digital storage device that can hold up to seven times more than the CD, which equates to about 9.4 (single-sided) to 17gb (double-sided) of data; in a DVD, there are multiple layers of the polycarbonate plastic.
  • Digitalis= a general term for cardiotonic glycosides used to treat congestive heart failure and atrial fibrillation.
  • Digitization=Process of converting an analog image into digital (binary) data for processing by a computer.
  • Dilation and curettage= Dilation of the cervix to allow the scraping of the uterine wall.
  • Dilation= the process of causing an increase in the diameter of a body opening, blood vessel, or tube.
  • Diluent= a substance, generally a fluid, that makes a solution or mixture less concentrated, less viscous, or more liquid.
  • Diode= A rectifying semiconductor made by sandwiching p-type crystal with an n-type to form a p-n junction.
  • Diphtheria= an acute contagious disease caused by the bacterium Corynebacterium diphtheriae. It is characterized by the production of a false membrane on mucosal surfaces and is usually accompanied by severe prostration.
  • Diploic space= Loose osseous tissue between the two tables of the skull.
  • Direct acquisition= A type of digital radiography in which the detector and reader are a permanent part of a table or wall unit; cassettes are not needed; converts incoming x-ray photons directly to an electronic signal.
  • Direct capture digital radiography= these devices convert the incident x-ray energy directly into an electrical signal, typically using a photoconductor as the x-ray absorber and a thin-film transistor as the signal collection area, and send the electrical signal to the computer for processing and viewing.
  • Direct contact= means of disease transmission in which infectious organisms are transferred to a susceptible host by the touch of an infected individual.
  • Direct conversion= conversion of x-ray energy to electrical signals without the light-conversion step.
  • Direct current (DC)= All electrons travel in the same direction.
  • Direct digital radiography (DR)= A type of digital radiography in which the detector and reader are a permanent part of a table or wall unit; cassettes are not needed.
  • Direct fusion= Equipment designed to image two modalities simultaneously and integrate the images.
  • Direct square law= A direct relationship is necessary to compensate for the changes in intensity and film density.
  • Direct variation= One quantity is a multiple of a second quantity.
  • Direct-to-Digital Radiographic (DDR) Systems=Method of creating digital radiographic images, also known as flat-panel or flat-plate imaging; involves the installation of a flat-panel image receptor in the Bucky of a radiographic table or upright Bucky, which sends an electronic signal directly to a digital image processor.
  • Dirty bomb= a device designed to spread radioactive material by conventional explosives when the bomb explodes. A dirty bomb kills or injures people through the initial blast of the conventional explosive and spreads radioactive contamination over possibly a large area—hence the term “dirty.” Such bombs could be miniature devices or large truck bombs. A dirty bomb is much simpler to make than a true nuclear weapon.
  • Disaster recovery= complete copy of the archive housed in another location and immediately available if the front-line archive goes down for any reason
  • Disinfectant= liquid chemical applied to objects to eliminate many or all pathogenic microorganisms.
  • Disintegrations per Minute (DPM)=A measure of the rate of ionizing emissions by radioactive substances.
  • Dislocation= Displacement of a bone no longer in contact with its normal articulation.
  • Displacement= Separation of bone fragments dissection= Separation of layers.
  • Display workstation= generally a display monitor where postprocessing occurs or where images can be viewed.
  • Disposable= not designed for reuse; intended to be thrown away after use. A disposable thermometer is a single-use adhesive paper device for measuring temperature by placement on a patient’s forehead.
  • Distal (disto-)=Refers to a structure that is situated away from the source or beginning. The foot is distal to the ankle. Or, The splenic flexure is distal to the hepatic flexure.
  • Distal= away from or farthest from the point of origin or attachment.
  • Distortion= One of the geometric properties affecting radiographic image quality; a misrepresentation of the size and shape of the structures being examined.
  • Distortion=Any undesired change in a wave form or signal.
  • Distortion=The misrepresentation of the size or shape of the structure being examined.
  • Distributed system= PACS workflow where the acquisition modalities send the images to a designated reading station and possibly review stations.
  • Distribution= Law of electrostatics that states charges reside on the surfaces of conductors but are evenly distributed throughout nonconductors.
  • Diuretic= a drug or other substance that tends to promote the formation and excretion of urine.
  • Diverticulitis= inflammation of one or more diverticula. The collection of fecal matter in the thin-walled diverticula causes inflammation and abscess formation in the tissues surrounding the colon.
  • Diverticulosis= the presence of pouch-like herniations through the muscular layer of the colon.
  • Diverticulum (plural, diverticula)= a pouch-like herniation through the muscular wall of a tubular organ. A diverticulum may be present in the esophagus, stomach, the small intestine, or, most commonly, the colon.
  • DNA= abbreviation for deoxyribonucleic acid, the protein substance of genes.
  • Dominant= Genes that always produce an effect.
  • Doppler= a sonographic device that allows the evaluation of flowing media, such as blood, by measuring the Doppler shift of the reflected ultrasound beam.
  • Dorsalis pedis pulse= see pedal pulse
  • Dorsiflexion=Backward bending, as of the hand or foot; brings toes and forefoot upward.
  • Dorsoplantar projection=X-ray beam that enters the top of the patient’s foot and exits through the bottom of the foot.
  • Dose (radiation)= radiation absorbed by a person’s body. Several different terms describe radiation dose.
  • Dose Area Product (DAP)=Measurement that incorporates the total dosage of radiation along with the area of field that is being used.
  • Dose Calibrator=A component in nuclear medicine equipment for determining the amount of radionuclide.
  • Dose coefficient= the factor used to convert radionuclide intake to dose. Usually expressed as dose per unit intake (e.g., sieverts per becquerel).
  • Dose equivalent limits=Maximum permissible radiation dose limits; used for radiation protection purposes.
  • Dose equivalent= The product of absorbed dose to a given organ or tissue multiplied by a quality factor (also known as a weighting factor [WF]), and then sometimes multiplied by other necessary modifying factors, to account for the potential for a biological effect resulting from the absorbed dose. (see Quality factor). It is expressed numerically in rem (traditional units) or sieverts (SI units).
  • Dose limit= Radiation exposure limits that are pertinent to the protection of radiation workers.
  • Dose rate= the radiation dose delivered per unit of time.
  • Dose reconstruction= scientific procedures that assist with 4 activities – managing victims of radiation emergencies, such as providing input to decisions on protection of emergency workers and members of the public or medical treatment of exposed individuals; providing exposed individuals or populations with information about the doses they received; investigating dose-response relationships in epidemiologic studies; determining whether individuals whose disease might have been induced by radiation qualify for compensation.
  • Dose-area product (DAP)=Used in DR systems to monitor the radiation output and dose to the patient per volume of tissue irradiated.
  • Dosimeter= A mechanism that can measure amounts of radiation.
  • Dosimeter= a small portable instrument (such as a film badge, thermoluminescent dosimeter [TLD], or pocket dosimeter) for measuring and recording the total accumulated dose of ionizing radiation a person receives.
  • Dosimeter= an instrument to detect and measure accumulated radiation exposure.
  • Dosimetry= assessment (by measurement or calculation) of radiation dose.
  • Dot pitch= measurement of how close the dots are located to one another within a pixel.
  • Down syndrome= a congenital condition characterized by varying degrees of mental retardation and multiple defects. Same as Trisomy 21.
  • Drip infusion= the administration of fluids or medications through an intravenous catheter by gravity flow.
  • Drive system= Part of the automatic processing transport system designed as a series of mechanical devices to turn the numerous rollers in the processor from power supplied by a single motor.
  • Dry imager= printer that uses heat to develop the film.
  • Dryer system= The final stage of film processing that removes the excess water, cools and dries the film, and seals the film for viewing and storage.
  • Drying= The process of film developing in which hot air is forced over both sides of the film as it exits the processor.
  • Dual focus= A two-filament arrangement within the x-ray tube.
  • Dual-Energy X-Ray Absorptiometry (DEXA)=X-rays with two separate energies used to obtain bone density data.
  • Duplication film= A type of film designed to provide an exact image of the original film.
  • Duplitized= Describes a film that is coated with emulsion of both sides.
  • Dura mater= Tough outermost meningeal covering dysphagia= Difficulty swallowing.
  • Dwell time= The time allotted for the fixer in a silver recovery unit to sit to permit chemical reactions to occur.
  • Dwell Time=The amount of time that the fixer solution is in contact with the active portion of the silver recovery device.
  • Dynamic range= The concept of contrast as it is displayed on a soft-copy monitor for digital images; range of density/brightness of the display monitor light emission.
  • Dynamic range=Range of gray shades that the imaging system can display; measured by the bit capacity for each pixel.
  • Dynamometer= Used to measure alternating current when electromagnets are used.
  • Dysentery= an inflammation of the intestine, especially of the colon, that may be caused by chemical irritants, bacteria, protozoa, or parasites and is characterized by diarrhea and abdominal cramping.
  • Dysphagia= difficulty in swallowing, commonly associated with obstructive or motor disorders of the esophagus.
  • Dysplasia= Disordered growth or faulty development of various tissues or body parts.
  • Dyspnea= difficult or painful breathing that may be caused by certain heart conditions, lung conditions, asthma, strenuous exercise, or anxiety.
  • Dyspnea= Shortness of breath.
  • EAM=External auditory meatus.
  • Earth=British terminology for zero=reference ground.
  • Echo time (TE)= The time between a 90-degree pulse and the echo during a spin-echo pulse sequence.
  • Echogenic= Producing a relatively strong reflection in ultrasound.
  • Ectopic pacemaker= Initiates abnormal heartbeats.
  • Ectopic pregnancy= Implantation occurring in the fallopian tube or pelvic cavity.
  • Ectopic= Abnormally positioned.
  • ED limit= a level of effective dose of radiation that has been recommended as an upper limit for individuals who are occupationally exposed to radiation.
  • Eddy current loss= Result of currents opposing the cause which produced them.
  • Edema= Accumulation of abnormal amounts of fluid in the intercellular tissue spaces or body cavities.
  • Edema= Swelling.
  • Edema= the abnormal accumulation of fluid in interstitial spaces of tissues. Also called swelling.
  • Edge enhancement= enhancement occurs when fewer pixels in the neighborhood are included in the signal average; the smaller the neighborhood, the greater the enhancement.
  • Edge enhancement= Increase in contrast due to
  • Edge Enhancement=The enhancement of structure margins (edges) using digital processing techniques.
  • Edge spread function (ESF)= Expression of the
  • Edge Spread Function=A graphic indication of image resolution.
  • Effaced= Wiped out or obliterated.
  • Effective dose= a calculated quantity developed by the ICRP (1991) for purposes of radiation protection. The effective dose is assumed to be related to the risk of a radiation-induced cancer or a severe hereditary effect. It takes into account= (1) the absorbed doses that will be delivered to the separate organs or tissues of the body during the lifetime of an individual due to intakes of radioactive materials; (2) the absorbed doses due to irradiation by external sources; (3) the relative effectiveness of different radiation types in inducing cancers or severe hereditary effects; (4) the susceptibility of individual organs to develop a radiation-related cancer or severe hereditary effect; (5) considerations of the relative importance of fatal and non-fatal effects; and, (6) the average years of life lost from a fatal health effect. (HPS 005-3) Thus, the effective dose is a quantity calculated by multiplying the equivalent dose received by every significantly irradiated tissue in the body by a respective tissue weighting factor (this factor reflects the risk of radiation-induced cancer to that tissue) and summing together the individual tissue results to obtain the effective dose. Such a dose, in theory, carries with it the same risk of cancer as would an equal equivalent dose delivered uniformly to the whole body.
  • Effective dose= The sum of the weighted equivalent doses for all irradiated tissues and organs; used to measure the radiation and organ system specific damage in man.
  • Effective focal spot= The area of the focal spot that is projected out of the tube toward the object being radiographed.
  • Effective Focal Spot=The area of the x-ray tube target that emits x-rays when viewed from the perspective of the image receptor.
  • Effective half-life= the time required for the amount of a radionuclide deposited in a living organism to be diminished by 50% as a result of the combined action of radioactive decay and biological elimination.
  • Effective target angle= In mammography, measured from the vertical central ray point.
  • Effectiveness of Care=The level of benefit when services are rendered under ordinary circumstances by average practitioners for typical patients.
  • Efferent= To carry away from the center or part effusion= Accumulation of fluid.
  • Efficacy of Care=The level of benefit expected when healthcare services are applied under ideal conditions.
  • Efficiency of Care=The highest quality of care delivered in the shortest amount of time with the least amount of expense and a positive outcome.
  • Eisenmenger’s syndrome= Ventricular septal defect associated with pulmonary hypertension and cyanosis resulting from right-to-left shunting.
  • Electric current= Electrons that are moving in predominantly the same direction.
  • Electric field= A force field; the result of the composite forces of the charges residing within an object.
  • Electrical circuit= A pathway that permits electrons to move in a complete circle from their source, through resisting electrical devices and back to the source.
  • Electrical energy= The result of movement of electrons; also known as electricity.
  • Electrical ground= the connection of an electric circuit to the earth, which becomes a part of the circuit. Grounding “drains off” excess charges, preventing electrical shocks and overheating of the circuit.
  • Electricity= The result of movement of electrons; also known as electrical energy.
  • Electrification= Describes the process of electron charges being added to or subtracted from an object.
  • Electrocardiogram (ECG, EKG)= a graphic record produced by an electrocardiograph, a device for recording heart rhythm by measuring electrical conduction through the heart.
  • Electrode= an electrical contact; a connection for conducting an electrical current from the body to physiological monitoring equipment.
  • Electrolarynx= an electromechanical device that enables a person without a larynx to speak.
  • Electrolysis=A process in which an electric charge causes a chemical change in a solution or molten substance.
  • Electrolyte balance= Equilibrium of electrolytes in the body.
  • Electrolyte= an element or compound that, when dissolved in water or another solvent, dissociates into ions, enabling the fluid to conduct an electric current. An appropriate electrolyte balance in blood and body tissues, especially sodium, calcium, and chlorides, is essential to transmission of nerve impulses.
  • Electrolyte= Element or compound that dissociates into ions in fluid.
  • Electrolytic= A type of silver recovery system that passes a current from a cathode to an anode through the fixer; the ionized silver is attracted to the negatively charged cathode.
  • Electromagnet = piece of metal, usually iron or steel, that temporarily becomes a strong magnet when an electric current is passed through a wire coiled around it.
  • Electromagnet= Temporary magnet produced by moving electric current.
  • Electromagnetic Coupling=The transfer of energy by means of a varying magnetic field. Inductive coupling.
  • Electromagnetic energy= A form of energy resulting from electric and magnetic disturbances in space.
  • Electromagnetic energy= pertaining to magnetism that is induced by an electric current. Also, energy in the form of electromagnetic waves, such as light, x-rays, and radio waves.
  • Electromagnetic radiation (EM)= A form of energy that is the result of electric and magnetic disturbances in space.
  • Electromagnetic radiation= A traveling wave motion that results from changing electric and magnetic fields. Types of electromagnetic radiation range from those of short wavelength, like x-rays and gamma rays, through the ultraviolet, visible, and infrared regions, to radar and radio waves of relatively long wavelengths
  • Electromagnetic relay= A device used to protect the radiographer from electric shock by isolating control buttons on the x-ray console from the actual circuit in which high voltage is flowing; similar to a circuit breaker.
  • Electromagnetic spectrum= Describes the different forms of electromagnetic radiation.
  • Electromagnetic=Referring to the combined electric and magnetic fields caused by electron motion through conductors.
  • Electromotive force (emf)= The force or strength of electron flow; also known as potential difference.
  • Electron (e)= Negatively charged subatomic particle of an atom.
  • Electron Beam Computed Tomography (EBCT)=A fifth-generation CT scanner design used in cardiac imaging.
  • Electron binding energy (Eb)= The amount of energy needed to remove the electron from the atom.
  • Electron volt (ev)= a unit of energy equivalent to the amount of energy gained by an electron when it passes from a point of low potential to a point one volt higher in potential.
  • Electron volt (ev)= Measurement of the binding energy of an electron; the energy one electron will have when it is accelerated by an electrical potential of 1 volt.
  • Electron Volt=A measure of the energy gained by an electron passing through an electric field produced by one volt.
  • Electron= an elementary particle with a negative electrical charge and a mass 1/1837 that of the proton. Electrons surround the nucleus of an atom because of the attraction between their negative charge and the positive charge of the nucleus. A stable atom will have as many electrons as it has protons. The number of electrons that orbit an atom determine its chemical properties.
  • Electronic medical record= All patient medical documentation stored in electronic formats.
  • Electrostatic Coupling=The transfer of energy by means of a varying electrostatic field. Capacitive coupling.
  • Electrostatic= The study of the distribution of fixed charges, or electrons, that are at rest.
  • Electrostatic=Pertaining to static electricity, or electricity at rest. An electric charge, for example.
  • Element= 1) all isotopes of an atom that contain the same number of protons. For example, the element uranium has 92 protons, and the different isotopes of this element may contain 134 to 148 neutrons. 2) In a reactor, a fuel element is a metal rod containing the fissile material.
  • Element= A simple substance; it cannot be broken down into any simpler substances by ordinary means.
  • Elephantiasis= Localized edema.
  • Elevate=To lift up or raise, positioning at a higher level.
  • Elongation= Projection of an object, making it appear longer than it really is.
  • Elongation=To make one axis of an anatomic structure appear disproportionately longer on the image than the opposite axis. Angling the central ray while the part and IR remain parallel with each other will elongate the axis toward which the central ray is angled.
  • Emaciation= A generalized wasting of body tissue.
  • Embolus= Any foreign matter, such as a blood clot or an air bubble, carried in the bloodstream.
  • Emesis= the act of vomiting, or a term for vomit.
  • EMF=Electromotive force (voltage).
  • EMI=Electromagnetic Interference.
  • Emission Spectrum=Graphic demonstration of the component energies of emitted electromagnetic radiation.
  • Empathy= the ability to recognize and to some extent share the emotions and state of mind of another and to understand the meaning and significance of that person’s behavior.
  • Emphysema= an abnormal condition of the pulmonary system characterized by overinflation and destructive changes of alveolar walls.
  • Emphysema= Pathologic accumulation of air in tissues or organs (especially as applied to a disease of the lungs).
  • Emphysema= The overdistention of lung tissues by air.
  • Empyema= Accumulation of pus in a cavity
  • Empyema= Pus in the thoracic cavity.
  • Emulsifier= Substance that acts like soap by dispersing the fat into very small droplets that permit it to mix with water.
  • Emulsion with crystals= A gelatin in which photosensitive silver halide crystals are suspended. It is an extremely thin coating that acts as a neutral lucent suspension medium for the silver halide crystals to separate and allow chemicals to interact with them.
  • En face= Face to face, looking at.
  • Endemic= constantly present within a community. Endemic describes diseases and physical or mental disorders.
  • Endemic= Present in a particular country, nation, or region.
  • Endogenous= Originating from within the body.
  • Endoscope= an illuminated optical instrument for the visualization of the interior of a body cavity or organ.
  • Endospore= a form assumed by certain bacteria in which they resist drying and can live for long periods without warmth, moisture, or nutrients.
  • Endosteum= Inner membrane lining the medullary cavity of a bone.
  • Endotracheal tube (ETT)=Stiff thick-walled tube used to inflate the lungs.
  • Endotracheal= within or through the trachea.
  • Enema= the introduction of a solution into the colon via the rectum for cleansing or therapeutic purposes.
  • Energy Resolution=The amount of variation in pulse size or spreading of the spectrum produced by a detector.
  • Engorgement= Congestion of a blood vessel or tissue with blood or other fluid.
  • Enriched uranium= uranium in which the proportion of the isotope uranium-235 has been increased by removing uranium-238 mechanically.
  • Enteral= within the small intestine, or via the small intestine.
  • Enteric= pertaining to the intestine.
  • Entrance roller= Specially designed crossover network to begin the film traveling from the feed tray down into the developer section.
  • Entrance skin exposure= The area where the maximum exposure received by the patient lies.
  • Entrance skin exposure=Absorbed dose to the most superficial layers of skin.
  • Envelope= The entire cathode and anode assembly is housed within this glass or metal structure.
  • Eosinophils= Granulocytic bilobed leukocyte.
  • Ependymoma= Tumor arising from the wall of the 4th ventricle, especially in children, and the lateral ventricles in adults.
  • Epidemic= the appearance of an infectious disease or condition that affects many people at the same time in the same geographical area.
  • Epidemiology= the study of the distribution and determinants of health-related states or events in specified populations; and the application of this study to the control of health problems.
  • Epididymis= Tightly coiled tube enclosed in a fibrous casing where final maturation of the sperm occurs.
  • Epilepsy, epileptic= a group of neurological disorders characterized by recurrent episodes of convulsive seizures, sensory disturbances, abnormal behavior, loss of consciousness, or all of these. Common to all types of epilepsy is an uncontrolled electrical discharge from the nerve cells of the cerebral cortex.
  • Epinephrine= an endogenous adrenal hormone and synthetic adrenergic vasoconstrictor. An important emergency drug for the treatment of anaphylaxis.
  • Epiphrenic diverticula= Outpouching found in the distal 10 cm of the esophagus.
  • Epiphyseal cartilage= Cartilaginous plate separating the epiphysis from the diaphysis.
  • Epiphysis= End of a long bone that at first is separated from the main part by cartilage, but later fuses with it by ossification.
  • Epistaxis= a nosebleed.
  • Epoetin= a recombinant version of human erythropoietin.
  • Equation= A statement that contains an equal sign.
  • Equivalent equation= Equations that have the same solutions.
  • Error maintenance= correction to equipment after errors have occurred.
  • Erythema= “radiation burn,” redness, or inflammation of the skin or mucous membranes caused by the dilation and congestion of superficial capillaries.
  • Erythropoietin= Protein serving as the humoral regulator of red blood cell formation.
  • Estrogen= Hormonal steroid compound that promotes secondary sex characteristics in female development.
  • Estrogen= one of a group of hormonal steroid compounds that promote the development of female secondary sex characteristics.
  • Ethics of care= theory that recognizes that right actions for one patient in one situation may be wrong for other patients or other circumstances. A caring ethic demands moral judgments that reflect community values such as respect, patience, tact, and kindness.
  • Ethics= the science or study of moral values or principles, including ideals of autonomy, beneficence, and justice; term is also applied to the moral values or principles themselves.
  • Ethnic= of or relating to a large group of people classed according to common cultural or racial origin.
  • Etiology= The study of disease causes (not a synonym for cause).
  • Euthanasia= the deliberate causing of the death of a person suffering from an incurable disease or condition.
  • Ev=Electron volt.
  • Event (planned event)= Examples: a scheduled nonemergency activity (e.g., sporting event, concert, parade, training exercise, large convention, fair, large gathering, etc.).
  • Eventration= Diaphragmatic—elevation of the diaphragm; abdominal—protrusion of the bowel or removal of abdominal viscera.
  • Eversion=Act of turning the plantar foot surface as far laterally as the ankle will allow.
  • Evisceration= the removal of the viscera from the abdominal cavity; disembowelment. Also, the removal of the contents from an organ or an organ from its cavity.
  • Exacerbation= Increase in the severity of a disease or any of its symptoms.
  • Excitation within 1 nanosecond.
  • Excitation= Process in which electrons in an atom are moved to a higher energy state without actually being removed from the atom.
  • Exenteration= Removal of all organs to debulk a tumor.
  • Exocrine gland= any of the multicellular glands that open onto the skin surface through ducts in the epithelium, as the sweat glands and the sebaceous glands.
  • Exogenous= Arising from outside the body.
  • Exophthalmos= Abnormal protrusion of the eyeball external fixation= Accomplished by the use of casts and splints.
  • Expiratory= pertaining to the exhalation of air from the lungs.
  • Exposure (radiation)= a measure of ionization in air caused by x-rays or gamma rays only. The unit of exposure most often used is the roentgen.
  • Exposure amplitude= The total distance the tube travels during the tomographic exposure.
  • Exposure field recognition=Digital radiography process in which the computer distinguishes the raw data representative of information within the exposure field from that which comes from outside the exposure field so that proper automatic rescaling can occur.
  • Exposure index (EI)= term used by Kodak to express exposure values.
  • Exposure indicator number= numerical representation of the amount of exposure, usually the mean value.
  • Exposure indicator=Readings obtained in computed radiography that express the amount of light given off by the imaging plate; indicates the amount of radiation exposure to the patient and imaging plate.
  • Exposure maintenance formula= A direct square law; mas must increase when distance         –  increases, and vice versa, in order to maintain image receptor exposure.
  • Exposure pathway= a route by which a radionuclide or other toxic material can enter the body. The main exposure routes are inhalation, ingestion, absorption through the skin, and entry through a cut or wound in the skin.
  • Exposure rate= a measure of the ionization produced in air by x-rays or gamma rays per unit of time (frequently expressed in roentgens per hour).
  • Exposure switch= A remote control device that permits current to flow through the circuit.
  • Extended cycle= A technique for processing radiographs whereby the speed of a standard film can be increased up to 35 percent and radiographic contrast increased measurably, by doubling the time the film is in the developer solution.
  • Extended Processing=A method of film processing that extends the normal developer time to increase image contrast.
  • Extension=Movement that results in straightening of a joint. With extension of the elbow, the arm is straightened. Extension of the cervical vertebrae shifts the patient’s head posteriorly in an attempt to separate the vertebral bodies.
  • External (lateral) rotation=Act of turning the anterior surface of an extremity outward or away from the patient’s torso midline.
  • External beam evaluation= The measurement of the quantity and quality of the external radiation beam.
  • External irradiation (or external exposure)= External irradiation occurs when all or part of the body is exposed to penetrating radiation from an external source. During exposure, this radiation can be absorbed by the body or it can pass completely through. A similar thing occurs during an ordinary chest x-ray. Following external exposure, an individual is not radioactive and can be treated like any other patient. Gamma or photon radiation exposure from a terrorist nuclear event or radiation dispersal device would make the victim at risk for Acute Radiation Syndrome, depending on the dose received.
  • External reduction= Fracture is manipulated without surgical incision.
  • Extracorporeal= pertaining to something that is outside the body.
  • Extrafocal radiation= Photons that were not produced at the focal spot; also called off-focus radiation.
  • Extramedullary hematopoiesis= Formation of red blood cells outside the bone marrow.
  • Extravasation= a passage or escape from a blood or lymph vessel into the tissues, usually of blood, serum, or lymph. With respect to intravenous fluids, the same as infiltration.
  • Extrinsic asthma= Environmental allergens.
  • Exudate= Material (fluid, cells, or cellular debris) that has escaped from blood vessels and has been deposited in tissues or on tissue surfaces, usually as a result of inflammation.
  • Fallout, nuclear= minute particles of radioactive debris that descend slowly from the atmosphere after a nuclear explosion.
  • False imprisonment= the intentional unjustified, nonconsensual detention or confinement of a person for any length of time.
  • Farad (f)= The unit of capacitance.
  • Farad=A unit of capacity that will store one coulomb of electrical charge when one volt of electrical pressure is applied.
  • Fasting= the act of abstaining from food for a specific period, usually for therapeutic or religious purposes.
  • Fat pad=Accumulation of adipose or fatty tissue that by its displacement can indicate joint effusion on radiographic images.
  • Fat-soluble vitamins= Vitamins stored in the body (A, D, E and K).
  • Fat-suppressed images= Requires saturation or full magnetization on the T1 sequence to ensure a large contrast difference between fat and water.
  • F-center=Empty lattice sites in photostimulable phosphors where crystal electrons are trapped following exposure to x-ray energy.
  • Fecalith= Intestinal stone formed around a center of fecal material.
  • Fellow= a graduate student who is paid for services rendered while receiving advanced education; in the health care setting, physicians receiving advanced train-ing in specialized areas may be designated as fellows.
  • Felony= a crime declared by statute to be more serious than a misdemeanor and deserving a more severe punishment.
  • Ferromagnetic= Materials that are highly permeable and susceptible to induction (e.g., iron, cobalt, nickel).
  • Fiberoptic cable= network communication medium that uses glass threads to transmit data on the network in the form of light.
  • Fiberoptics= a technical process that uses glass or plastic fibers to transmit light through a specially designed tube and reflect a magnified image by which an internal organ or cavity can be viewed.
  • Fibrillation= involuntary recurrent contraction of a single muscle fiber or of an isolated bundle of nerve fibers. Fibrillation of heart muscle is an ineffective quivering motion that replaces normal heart rhythm and may be life threatening.
  • Fibrin= Essential portion of a blood clot.
  • Fibrinolysis= Breaking up of a blood clot.
  • Fibrocystic breast disease= the presence of single or multiple cysts that are palpable in the breasts. The cysts are benign and fairly common, yet must be considered potentially malignant and observed carefully for growth or change.
  • Fibromuscular dysplasia (FMD)= Arterial disorder characterized by intramural folds of fibrous endothelial tissue.
  • Fibrosarcoma= Malignant tumor of the metaphysics of bone resulting in reduction of bone composition.
  • Field effect transistor (FET)= device within an imaging detector that isolates each pixel element and reacts like a switch to send the electrical charges to the image processor.
  • Field of view (FOV)=Area of the image receptor from where the image data is collected. For computed radiography, the area is the entire imaging plate and for direct or indirect digital radiography it is the detectors that are included in the exposure field, as determined by collimation.
  • Field survey instrument= Portable device used to measure radiation in a given location.
  • Field Uniformity=Refers to the even distribution of magnetic field strength in the region of interest.
  • Field=An area through which electric and/or magnetic lines of force pass.
  • Filament A small coil of thin thoriated tungsten wire.
  • Filament circuit= Supplies the filament of the x-ray tube with properly modified power.
  • File room workstation= workstation found in the radiology file room that may be used to burn cds or print films for outside use.
  • File Transfer Protocol (FTP)=A method for transferring files across a computer network.
  • Fill Factor=The percentage of pixel area that is sensitive to the image signal (contains the x-ray detector). The fill factor for most current systems is approximately 80% because some of the pixel area must be devoted to electronic conductors and the thin film transistor (TFT).
  • Film badge dosimeter Two pieces of film having different sensitivities to x-rays contained within a light, tight envelope; the film emulsion darkens in response to the radiation exposure received.
  • Film digitizer= device that scans hard copy x-ray images and converts them to digital images.
  • Film processing system= The equipment used to process radiographic film for viewing of the radiographic image
  • Filter= Any material designed to effectively absorb photons from the x-ray beam.
  • First pass effect= decrease in the therapeutic effect of a drug before it reaches the target tissue as a result of passing first through the liver via the portal circulation.
  • First receiver= Healthcare workers in a hospital or other facility where victims arrive for treatment. First receivers provide medical care at locations remote from the incident and not at the site of a hazardous materials release. Since victims may arrive for treatment still contaminated with hazardous materials, first receivers must also protect themselves by putting on appropriate PPE before delivering medical care.
  • First responder= An individual responsible for protecting and preserving life, property, evidence, or the environment during the earliest stages of a mass casualty event or other emergency. First responders generally work at or near the incident site.
  • Fissile material= any material in which neutrons can cause a fission reaction. The three primary fissile materials are uranium-233, uranium-235, and plutonium-239.
  • Fission (fissioning)= the splitting of a nucleus into at least two other nuclei that releases a large amount of energy. Two or three neutrons are usually released during this transformation.
  • Fissures= Deep grooves that divide each cerebral hemisphere into lobes.
  • Fistula, fistulous tract= abnormal passage from an internal organ to the body surface or between two internal organs, often the result of infection.
  • Fistula= Abnormal connection, usually between two internal organs or from an internal organ to the surface of the body.
  • Fixed mode= postprocessing mode in which the user selects the exposure index: latitude is set by the menu selection; no histogram is generated, and there is no recognition of imaging plate division; the resultant image is a direct reflection of the exposure value.
  • Fixed= A piece of equipment that remains in one place and is not movable.
  • Fixer=Processing solution responsible for removal of undeveloped silver halide and hardening of the film emulsion.
  • Fixing= The process of removing undeveloped silver halides to make the image permanent for viewing.
  • Flail chest= a thorax in which multiple rib fractures cause instability in part of the chest wall and paradoxical breathing, with the lung underlying the injured area contracting on inspiration and bulging on expiration.
  • Flat field detector= Descriptive term used for the plates used in both direct and indirect digital systems.
  • Flat panel detector= Descriptive term used for the plates used in both direct and indirect digital systems.
  • Flat panel detector= detector that consists of a photoconductor, which holds a charge on its surface that can then be read out by a thin-film transistor.
  • Flavivirus= a genus of a family of Flaviviridae single-stranded positive-sense ribonucleic acid viruses, including species that cause yellow fever, Dengue fever, and St. Louis encephalitis.
  • Fleming’s hand rules= A series of easily remembered aids to help with the relationship between electricity and magnetism.
  • Flexion=Movement that bends a joint. With flexion of the elbow, the arm is bent. Flexion of the cervical vertebrae shifts the patient’s head forward in an attempt to bring the vertebral bodies closer.
  • Flip angle= Rotation of magnetization due to a Larmor frequency pulse.
  • Floating=Referring to a circuit which has no connection to ground.
  • Flood replenishment= A type of replenishing system used for low-volume systems; controlled by a timer that floods the developer and fixer tanks with replenisher at regular intervals.
  • Flood Replenishment=A timed method of replenishing processing solutions with an automatic processor.
  • Floor suspension system= A type of radiography unit that uses a tube support column mounted on the floor.
  • Floor-to-ceiling suspension system= A type of radiography unit that uses a pair of rails for longitudinal positioning.
  • Flora= microorganisms that live on or within a body to compete with disease-producing microorganisms and provide a natural immunity against certain infections.
  • Flow Meter=A device for measuring the volume of liquid flowing through it.
  • Flowchart=A pictorial representation of the individual steps required in a process.
  • Fluid overload= an excessive accumulation of fluid in the body caused by excessive parenteral infusion or deficiencies in cardiovascular or renal fluid volume regulation. Same as hypervolemia.
  • Fluorescence= The ability of a material to emit light instantaneously in responses to
  • Fluorescence= the emission of light of one wavelength (usually ultraviolet) when exposed to energy of a different, usually shorter wavelength.
  • Fluorescence=The type of luminescence that is desired for use in intensifying screens because it occurs when certain crystals emit light within 10−8 seconds after being exposed to radiation.
  • Fluorescent in situ hybridization (FISH)= a cytogenetic technique used to detect and localize the presence or absence of specific DNA sequences on chromosomes.
  • Fluoroscope= a device used for the immediate projection of a radiographic image on a fluorescent screen or cathode ray tube monitor for visual examination.
  • Fluoroscopic screen= A specialized x-ray tube with an image receptor which can be viewed during an x-ray exposure.
  • Fluoroscopic spot filming= A type of imaging that is done with 70 mm roll film or 105 mm film chips that are sensitive to green light.
  • Fluoroscopy= A dynamic radiographic examination; involves active diagnosis during an examination.
  • Flushing, flushed= a prolonged reddening of the face such as that caused by a reaction to certain drugs.
  • Flux density= Determined by field strength and the arc in which the lines of flux are located.
  • Flux gain= A measurement of the increase in light photons due to the conversion efficiency of the output screen.
  • Flux Gain=The gain in image brightness occurring with an image intensifier during fluoroscopy resulting from the high voltage across the tube.
  • FM=Frequency modulation.
  • FMEA (Failure Mode and Effects Analysis)=A procedure for analysis of potential failure within a system, classifying the severity or determining the failure’s effect upon the system, and help determine remedial actions to overcome these failures.
  • Focal plane= The section; also section level, layer height, object plane, depth of focus.
  • Focal point= The portion of the anode where the high-voltage electron stream will impact.
  • Focal Spot Blooming=An increase in stated focal spot size, usually as a result of an increase in milliampere.
  • Focal spot= a small area on an x-ray tube target where the electron stream strikes the target and x-rays are produced.
  • Focal spot= The portion of the anode where the high-voltage electron stream will impact.
  • Focal track= The portion of the anode where the high-voltage electron stream will impact. When discussing a rotating anode this describes the circular path that will be impacted by the electron beam.
  • Focal= Localized.
  • Focus Group=Group dynamic tool for problem identification and analysis.
  • Focus= The portion of the anode where the high-voltage electron stream will impact.
  • Focused grid= A grid created with the central grid strips parallel with the strips becoming more inclined as they move away from the central axis; the lines would intersect along a point in space called the line of convergence.
  • Focused grid= grid in which the scatter absorbing lead lines are tilted so that at a prescribed distance, the lines will converge.
  • Focusing cup= A shallow depression in the cathode assembly designed to house the filament.
  • FOCUS-PDCA=A quality management method developed by the Hospital Corporation of America.
  • Follicular carcinoma= Neoplasm with a follicular arrangement of cells.
  • Fomite= nonliving material such as bed linen that may transmit microorganisms.
  • Footboard= A piece of equipment used with a tilting table that allows the patient to stand when the table is upright.
  • Foot-Candle=Measurement of illuminance: lumens per square foot = foot-candles.
  • Forceps= any of a large variety of surgical instruments, all of which have two handles or sides, each attached to dull blades that move in opposition to each other like scissors.
  • Foreshorten=To make one axis of an anatomic structure appears disproportionately shorter on the image than the opposite axis. Positioning the long axis of the lower leg at a 45-degree angle with the IR while the central ray is perpendicular to the IR foreshortens the image of the lower leg on the image.
  • Foreshortening= Projection of an object, making it appear shorter than it really is.
  • Fractional focal spot= A very small focal spot; usually a fraction of a millimeter in size.
  • Fractionated exposure= exposure to radiation that occurs in several small acute exposures, rather than continuously as in a chronic exposure.
  • Free induction decay (FID)= The simplest form of loss of the MR signal due to protons becoming out of phase with one another.
  • Frequency Response=The amplitude versus frequency characteristics of a device. Also may refer to the range of frequencies over which the device operates within prescribed performance
  • Frequency, Power=Normally, the 50 or 60 hertz power used to operate most AC powered equipment. The frequency of AC power supplied by electric utilities companies.
  • Frequency= The number of waves that passes a particular point in a given time frame.
  • Frequency= with respect to a sine wave, the number of times per second that a wave crest passes a given point
  • Frequency=The number of repetitions of any phenomenon within a fixed period.
  • Frequency=The number of times a periodic action occurs in one second. Measured in Hertz.
  • Friction= Electrification that occurs when one object is rubbed against another and, due to differences in the number of electrons available on each, electrons travel from one to the other.
  • Frog-leg position=Position where the affected leg(s) is flexed and abducted to demonstrate a lateral projection of the hip and proximal femur.
  • FSK=Frequency Shift Keying.
  • Fulcrum= The pivot point around which the motions of the tube and the image receptor are centered.
  • Full-wave rectification= The conversion of the opposing half of the incoming electron flow to always move in the same direction, instead of discarding half the cycle.
  • Full-Width Half Maximum (FWHM)=A measure of resolution equal to the width of an image of a line source at points where the intensity is reduced to half the maximum.
  • Functional MR (FMR)= Allows the localization of specific regions of the brain that correspond to various functions.
  • Fundoplication= Taking tucks in the fundus of the stomach and distal esophagus.
  • Fungus (plural, fungi)= a type of organism that requires an external carbon source. The two basic types are molds and yeasts.
  • Fuse= A device constructed to interrupt a circuit before a dangerous temperature is reached.
  • Fusiform= Spindle shaped.
  • Fusion imaging= use of computerized hybrid imaging systems that perform dual processes to obtain both anatomic and functional information. The basic types combine PET with CT, PET with MRI, and SPECT with CT.
  • Fusion Imaging=A combination of two images such as PET and CT.
  • Fusion= a reaction in which two lighter nuclei unite to form a heavier one, releasing energy in the process. Reactions of this type are responsible for the release of energy in stars or in thermonuclear devices.
  • Gadolinium= an element that is a component of certain intensifying screen phosphors and of paramagnetic contrast agents.
  • Gain=The increase of voltage, current, or power over a standard or previous reading. Usually expressed in decibels.
  • Galeazzi’s fracture= Combination fracture of the shaft of the radius with a posterior dislocation of the ulna.
  • Galvanometer = instrument used to measure and detect small electric currents.
  • Galvanometer= Used to measure direct current when permanent magnets are used.
  • Gamma camera= a device that uses the emission of light from a crystal struck by gamma rays to produce an image of the distribution of radioactive material in a body organ. The light is detected by an array of light-sensitive electronic tubes and is converted to electric signals for further processing.
  • Gamma camera= A sodium iodide crystal detects the ionizing radiation emitted from the patient.
  • Gamma Camera=A device used for image acquisition in many nuclear medicine procedures.
  • Gamma rays=  high-energy electromagnetic radiation emitted by certain radionuclides when their nuclei transition from a higher to a lower energy state. These rays have high energy and a short wave-length. All gamma rays emitted from a given isotope have the same energy, a characteristic that enables scientists to identify which gamma emitters are present in a sample. Gamma rays penetrate tissue farther than do beta or alpha particles but leave a lower concentration of ions in their path to potentially cause cell damage. Gamma rays are very similar to x-rays.
  • Gamma= A measure of the slope of the straight line portion of the D log E curve at the speed point.
  • Gantry= The movable frame of the CT unit.
  • Gantry= the portion of an MRI or CT unit that surrounds the patient, emits imaging energy, and detects information needed for image formation.
  • Gas gangrene= necrosis (tissue death) accompanied by gas bubbles in soft tissue after surgery or trauma. It is caused by anaerobic organisms. Gas gangrene causes toxic delirium and is rapidly fatal if untreated.
  • Gas-Filled Detector=A category of radiation detector consisting of a gas-filled chamber.
  • Gasses= A light mixture that has neither shape nor volume.
  • Gastrinoma= Tumor found in the pancreas and duodenum that is associated with peptic ulcers.
  • Gastrointestinal (GI)= pertaining to the organs of the alimentary tract, from mouth to anus.
  • Gastroscopy= the visual inspection of the interior of the stomach by means of a special fiberoptic instrument, a gastroscope, inserted through the mouth and esophagus.
  • Gauss (G)= The unit used for measuring magnetic flux density.
  • Geiger counter= a radiation detection and measuring instrument consisting of a gas-filled tube containing electrodes, between which an electrical voltage but no current flows. When ionizing radiation passes through the tube, a short, intense pulse of current passes from the negative electrode to the positive electrode and is measured or counted. The number of pulses per second measures the intensity of the radiation field. Geiger counters are the most commonly used portable radiation detection instruments.
  • Geiger-Müller (GM) Meter=A survey meter used mainly for radiation protection purposes as a survey instrument and an area monitor.
  • Geiger-Müller Tube=A type of gas-filled radiation detector.
  • Generator= A device that converts mechanical energy to electrical energy using moving lines of flux in relationship to a conductor to induce current; also known as a dynamo.
  • Generic= pertaining to a substance, product, or drug that is not protected by trademark.
  • Genetic effects= hereditary effects (mutations) that can be passed on through reproduction because of changes in sperm or ova.
  • Genetic= Describes the effects of radiation that appear in the descendants of the individual being irradiated.
  • Geomagnetism = natural magnetism of earth.
  • Germicide, germicidal= a chemical that kills pathogenic microorganisms.
  • Gestation, gestational= in viviparous animals, the period from the fertilization of the ovum until birth. Gestation varies with the species; in humans the average duration is 266 days, or approximately 280 days from the onset of the last menstrual period.
  • Giant cell tumor (osteoclastoma)= Frequently occurring of the end of a long bone as a mass surrounded by a thin shell of new periosteal bone.
  • Giardiasis= an inflammatory intestinal condition. The source of infection is usually untreated water contaminated with Giardia lamblia cysts. Also called traveler’s diarrhea.
  • Giga=One billion.
  • Gigahertz (ghz)=A unit of frequency equal to one billion hertz.
  • Gigantism= Excessive size and stature.
  • Glabelloalveolar line=Imaginary line connecting the glabella and alveolar ridge.
  • Glioblastomas= Neoplasm consisting of embryonic epithelial cells developing around the neural tube, transforming to supportive connective tissue of the nerve cells or ventricle lining.
  • Gliomas= Largest group of primary brain tumors, composed of malignant glial cells.
  • Glomerulus= Tuft or cluster.
  • Glucagon= a hormone produced by the pancreas that is important in carbohydrate metabolism. An identical commercial preparation is available for the treatment of hypoglycemia and is used in imaging procedures to cause relaxation of the smooth muscle of the gastrointestinal tract.
  • Glucocorticoid= Regulates carbohydrate metabolism and is regulated by the adrenocorticotropic hormone.
  • Glucose= a simple sugar found in certain foods, especially fruits, and a major source of energy present in human and animal body fluids.
  • Gluteal fat plane=Fat plane that is superior to the femoral neck.
  • Glycogen= Stored excess glucose.
  • GND=Ground.
  • Gonadal dysgenesis= Variety of conditions related to abnormal development of the gonads.
  • Gout= A metabolic disease that can cause a reduction in bone composition.
  • Gradient point= The slope of any portion of the D log E curve.
  • Grading= Assessment of a tumor to determine the degree of aggressiveness or malignancy.
  • Gram’s method= Technique for staining microorganisms.
  • Grand mal seizure= a seizure characterized by loss of consciousness and repeated rigid arching of the back alternating with periods of relaxation. Same as major motor or tonic-clonic seizure.
  • Grand mal seizure= Epileptic seizure characterized by generalized involuntary muscular contractions and cessation of respiration that precedes tonic and clonic spasms of the muscles.
  • Granulation tissue= Combination of young developing capillaries and actively proliferating fibroblasts producing connective tissue fibers.
  • Granule= a particle, grain, or other small, dry mass capable of free movement. Unlike powders, granules are usually free flowing because of small surface forces involved.
  • Granuloma= Tumor like mass of tissue caused by a chronic inflammatory process.
  • Gray (Gy)= The new international system (SI) unit of radiation dose, expressed as absorbed energy per unit mass of tissue. The SI unit “Gray” has replaced the older “rad” designation. (1 Gy = 1 joule/kilogram = 100 rad). Gray can be used for any type of radiation (e.g., alpha, beta, neutron, gamma), but it does not describe the biological effects of different radiations. Biological effects of radiation are measured in units of “Sievert” (or the older designation “rem”). Sievert is calculated as follows= Gray multiplied by the “radiation weighting factor” (also known as the “quality factor”) associated with a specific type of radiation.
  • Gray (Gy)= Unit of absorbed energy or dose; 1 joule of energy absorbed in each kilogram of absorbing material.
  • Green Film=Film that has not been processed.
  • Greenstick fracture= Incomplete fracture of one cortex.
  • Grid cut-off= The result of the primary beam being angled into the lead strips.
  • Grid cutoff=Reduction in the amount of primary radiation reaching the IR because of grid misalignment.
  • Grid frequency= number of grid lines per inch.
  • Grid frequency= The number of grid lines per inch or centimeter.
  • Grid Latitude=The margin of error in centering the central ray of the x-ray beam to the center of the grid.
  • Grid ratio= ratio of the height of the grid line to the width of the interspace material.
  • Grid ratio= The ratio of the height of the lead strips to the distance between the strips.
  • Grid= a device placed between the patient and the image receptor during a radiographic examination to limit the amount of scatter radiation reaching a radiographic image receptor, thereby increasing the image contrast.
  • Grid= A device used to improve contrast of the radiographic image.
  • Grid=Device consisting of lead strips that is placed between the patient and IR to reduce the amount of scatter radiation reaching the receptor.
  • Grid-biased= A type of tube that quickly regulates the flow of electrons, producing x-ray photons.
  • Grid-controlled= A type of tube that quickly regulates the flow of electrons, producing x-ray photons.
  • Grid-pulsed= A type of tube that quickly regulates the flow of electrons producing x-ray photons.
  • Gross negligence= negligent acts that involve reckless disregard for life or limb. It denotes a higher degree of negligence than ordinary negligence and results in more serious penalties.
  • Ground Conductor=A conductor in a transmission cable or line that is grounded.
  • Ground Loop=A completed circuit between shielded pairs of a multiple pair created by random contact between shields. An undesirable circuit condition in which interference is created by ground currents when grounds are connected at more than one point.
  • Ground potential= A neutral reference point for discussing charges; the earth is defined as zero.
  • Ground Potential=The potential of the earth. A circuit, terminal, or chassis is said to be at ground potential when it is used as a reference point for other potentials in the system.
  • Ground=An electrical connection between a circuit and the earth. Also refers to a conductor connected to earth. In some instances, can refer to a central metallic point designated as having “zero” potential.
  • Gyri= Winding convolutions of the cerebral hemispheres.
  • Gyromagnetic ratio= The ratio of the magnetic moment to the moment of inertia.
  • Halation= An effect on a radiographic image caused when light that is reflected from the air interfaces on the back of the base material.
  • Half-life= the time any substance takes to decay by half of its original amount.
  • Half-life= the time required for a radioactive substance to lose 50% of its activity through decay.
  • Half-value layer (HVL)= The amount of absorbing material that will reduce the intensity of the primary beam to one-half its original value.
  • Half-Value Layer=The amount of filtering material that reduces the intensity of radiation to one half of its previous value.
  • Half-wave rectification= Suppressed rectification resulting from only half of the incoming alternating current being converted to pulsating direct current; called self-rectification.
  • Hallucinogen= a substance that causes excitation of the central nervous system, characterized by hallucination, mood change, anxiety, sensory distortion, delusion, depersonalization; increased pulse, temperature, and blood pressure; and dilation of the pupils.
  • Handgrip= A piece of equipment that allows the patient to grip when the table is being tilted for added support and reassurance.
  • Hanging protocol= how a set of images will be displayed on the monitor.
  • Hangman’s fracture= Fracture of the arch of C2 anterior to the inferior facet; associated with anterior subluxation of C2 and C3.
  • Hantavirus= a genus of viruses in the Bunyaviridae family. Hantavirus is the cause of several different forms of hemorrhagic fever with renal syndrome.
  • Hard copy= Images that are visualized on film.
  • Hard drive= main repository for programs and documents on the computer.
  • Hardener= A chemical used in film processing that controls the swelling of the gelatin to prevent scratches and abrasions to the emulsion during processing; in a fixer solution must function in an acidic environment.
  • Hardware= Computer equipment.
  • Head unit= Specialized radiography equipment used to conduct cranial studies.
  • Health physics= a scientific field that focuses on protection of humans and the environment from radiation. Health physics uses physics, biology, chemistry, statistics, and electronic instrumentation to help protect individuals from any damaging effects of radiation.
  • Heat exchanger= The part of the automatic processing system in which a thermostat is used to heat the developer which is then routed to a circulation coil to heat the fixer by conduction.
  • Heat= The result of the motion of atoms and molecules; also known as thermal energy
  • Heberden’s nodes= Small, hard nodules at the distal interphalangeal joints of the fingers produced by calcific spurs of the articular cartilage and associated with osteoarthritis.
  • Heimlich Maneuver= an emergency procedure for dislodging food or other obstruction from the trachea to prevent asphyxiation. Also called abdominal thrust.
  • Helical= Spiral continuous motion.
  • Hematogenous= Spread by means of the bloodstream.
  • Hematoma= a collection of extravasated blood trapped in the tissues of the skin or in an organ, resulting from trauma or incomplete hemostasis after surgery.
  • Hematoma= Hemorrhage trapped in body tissues.
  • Hemodynamic= Pertaining to the movements involved in the circulation of the blood.
  • Hemodynamics= the physical aspects of blood circulation, including cardiac function and peripheral vascular physiological characteristics.
  • Hemoglobin= a complex protein-iron compound in the blood that carries oxygen to the cells from the lungs and carbon dioxide away from the cells to the lungs.
  • Hemoglobin= Complex protein-iron compound in the blood that carries oxygen.
  • Hemolytic uremia syndrome= a rare kidney disorder marked by renal failure, microangiopathic hemolytic anemia, and platelet deficiency. The syndrome, the cause of which is unknown, usually occurs in infancy.
  • Hemoptysis= Coughing up blood or bloodstained sputum.
  • Hemorrhage, hemorrhagic= a loss of a large amount of blood in a short period, either externally or internally. Hemorrhage may be arterial, venous, or capillary.
  • Hemorrhage= Bleeding or abnormal blood flow from a vessel into tissue.
  • Hemorrhoid= a varicosity in the lower rectum or anus caused by congestion in the veins of the hemorrhoidal plexus.
  • Hemostat= a procedure, device, or substance that arrests the flow of blood. Common term for small forceps used to clamp blood vessels or tubing.
  • Hemothorax= an accumulation of blood and fluid in the pleural cavity, between the parietal and visceral pleura, usually the result of trauma.
  • Hemothorax= The filling of the pleural cavity with blood.
  • Henry=Unit of inductance (H) that will produce a voltage drop of one volt when the current changes at the rate of one ampere per second.
  • Heparin lock= a small adapter with a diaphragm that is attached to an intravenous (IV) catheter when more than one injection is anticipated. Same as intermittent injection port.
  • Heparin= an anticoagulant that prevents intravascular clotting.
  • Hepatic= pertaining to the liver.
  • Hepatitis= an inflammatory condition of the liver, characterized by jaundice, hepatomegaly (liver enlargement), anorexia, abdominal and gastric discomfort, abnormal liver function, clay-colored stools, and tea-colored urine.
  • Hepatitis= Inflammatory disease of the liver.
  • Hereditary= Transmitted to offspring through genes.
  • Herniation= a protrusion of a body organ or portion of an organ through an abnormal opening in a membrane, muscle, or other tissue.
  • Herpes= any of several kinds of diseases caused by herpesvirus and characterized by eruption of blisters on the skin or mucous membranes. Herpes simplex virus 1 (oral herpes, herpes labialis) and herpes simplex virus 2 (genital herpes, herpes genitalis) are forms of the herpes simplex virus (HSV). Herpes zoster is the causative agent of chicken pox and shingles.
  • Hertz (Hz)=Unit of frequency equal to one cycle per second.
  • Heterogeneous= Composed of materials that have different structures or qualities.
  • HF=High Frequency. International Telecommunication Union designation for the 3=30 mhz band of frequencies.
  • Hiatal hernia= protrusion of a portion of the stomach upward through the diaphragm. The condition occurs in about 40% of the population, and most people display few, if any, symptoms.
  • High Frequency=International Telecommunication Union designation for the 3=30 mhz band of frequencies.
  • High-Contrast Resolution=The ability to resolve small, thin black-and-white areas.
  • High-Contrast Spatial Resolution=The minimum distance between two objects that allows them to be seen as separate and distinct.
  • High-Efficiency Particulate Air Filter (HEPA)= a filter that is at least 99.97% efficient in removing monodisperse particles of 0.3 micrometers in diameter. The equivalent NIOSH 42 CFR 84 particulate filters are the N100, R100, and P100 filters.
  • High-Frequency Generator=A type of x-ray generator that dramatically increases the frequency of alternating current sent to the x-ray tube.
  • High-level radioactive waste= the radioactive material resulting from spent nuclear fuel reprocessing. This can include liquid waste directly produced in reprocessing or any solid material derived from the liquid waste having a sufficient concentration of fission . Other radioactive materials can be designated as high-level waste if they require permanent isolation. This determination is made by the U.S. Nuclear Regulatory Commission on the basis of criteria established in U.S. law.
  • Highly enriched uranium (HEU)= uranium that is enriched to above 20% uranium-235 (U-235). Weapons-grade HEU is enriched to above 90% in U-235.
  • High-pass filtering; also known as sharpening.
  • High-pass filtering= Amplifies or deletes all but the high frequencies.
  • High-pass filtering= technique for the enhancement of contrast and edge that amplifies the frequencies of areas of interest that are known (those frequencies that can be amplified) and suppresses frequencies outside the area of interest.
  • Hill-Sachs defect=Posterolateral humeral head notch defect created by impingement of the articular surface of the humeral head against the anteroinferior rim of the glenoid cavity.
  • HIPAA (Health Insurance Portability and Accountability Act)=Enacted in 1996 (also known as the Kennedy-Kassebaum Act or Public Law 104-191) to simplify healthcare standards and save money for healthcare businesses by encouraging electronic transactions.
  • Hirschsprung’s disease= see congenital megacolon.
  • Histamine= a compound, found in all cells, produced by the breakdown of histidine. It is released in allergic and inflammatory reactions and causes dilation of capillaries, decrease in blood pressure, increase in secretion of gastric juice, and constriction of smooth muscles of the bronchi and uterus.
  • Histogram analysis error=Image histogram that includes raw data values in the volume of interest that should not be included; this results in a misshapen histogram that will not match the lookup table closely enough for the computer to rescale the data accurately.
  • Histogram Error=Improper optical density resulting from selection of an incorrect preprocessing histogram in a cathode-ray system (such as using an adult histogram when radiographing a pediatric chest).
  • Histogram= Generated by dividing a scanned area into pixels and determining the signal intensity for each pixel; can be calculated for specific anatomy and procedures.
  • Histogram= graphic representation of all of the digitally recorded signals of a digital x-ray exposure.
  • Histogram=A data display tool in the form of a bar graph that plots the most frequent occurrence of a quantity in the center.
  • Histogram=Graph that is generated from the raw data that has the pixel brightness value on the x-axis and the number of pixels with that brightness value on the y-axis.
  • Histology= Microscopic examination to determine tissue structure.
  • Histoplasmosis= an infection caused by inhalation of spores of the fungus Histoplasma capsulatum.
  • Hives= blotchy reddening of the skin with itching. Same as urticaria.
  • Hl-7= health level 7; standard protocol used for medical data systems.
  • Homogeneous= Composed of material of similar or identical structure or quality.
  • Homogeneous=Uniformity between structures.
  • Homogenous Phantom=A device used in quality control testing that is uniform in thickness and density.
  • Horizontal Distance Measurement=A quality control test for ultrasound equipment requiring measurements taken perpendicular to the sound beam axis.
  • Horseshoe kidney= Fusion of the lower poles of the kidneys.
  • Hospice= an approach to care for the terminally ill that seeks to provide comfort without treating the underlying disease.
  • Hospital information system (HIS)= information system used throughout the hospital, includes direct patient care information, billing systems, and reporting systems.
  • Hospital information system (HIS)= The electronic database used in the hospital to store, generate, and retrieve information on patients.
  • Hospitalist= physician specialist, often an internist, who limits practice to treatment of hospital inpatients.
  • Hot spot= any place where the level of radioactive contamination is considerably greater than the area around it.
  • Housing cooling chart= Permits the calculation of the time necessary for the housing to cool enough for additional exposures to be made.
  • Hum=Term used to describe noise in a audio, video, or other system that comes from 60 Hz power or its harmonic(s). So named for the low=frequency humming sound produced in audio systems. Usually hum is the result of undesired coupling from a 60 Hz source or of inadequate filtering of the DC output of an AC input power supply.
  • Human immunodeficiency virus (HIV)= a retrovirus that causes acquired immunodeficiency syndrome (AIDS). It is transmitted through contact with an infected individual’s blood, semen, breast milk, cervical secretions, cerebrospinal fluid, or synovial fluid. HIV infects T-helper cells of the immune system and causes infection with a long incubation period before manifesting the symptoms of AIDS.
  • Humidity=A measurement of the relative level of moisture in the air.
  • Hurter and Driffield (H&D) curve= A radiographic relationship between the amount of exposure and the resultant density on the film; also known as characteristic curve, sensitometric curve, and D log E curve.
  • Hydration= a chemical process in which water is taken up by a chemical without disrupting the rest of the molecule; also, the process of supplying water to a person to restore or maintain the body’s fluid balance.
  • Hydrocephalus= Dilatation of fluid-filled cerebral ventricles resulting in enlargement of the head.
  • Hydrocephalus= Enlargement of the head resulting from an abnormal increase in fluid within the ventricular system.
  • Hydrolyzed Reduced Technetium=A type of technetium-99m used in radionuclide imaging.
  • Hydrometer=A device for measuring specific gravity.
  • Hydronephrosis= Distention of the pelvis and calyces of the kidney.
  • Hydroquinone A developing agent that slowly reduces silver and produces heavy density.
  • Hydrosalpinx= Fallopian tube cystically enlarged with clear fluid.
  • Hydrostatic pressure= the pressure exerted by a liquid. The hydrostatic pressure of an intravenous infusion is determined by the height of the fluid container with respect to the vein.
  • Hydrothorax= The filling of the pleural cavity with serous fluid.
  • Hydroureter= Dilatation of the ureter.
  • Hygroscopic= tending to absorb moisture.
  • Hyperactive= Increased activity.
  • Hyperextension= the position of maximum extension of a joint.
  • Hyperglycemia= abnormally elevated level of blood glucose, characteristic of uncontrolled diabetes mellitus.
  • Hyperglycemia= Greater amount of glucose than normal in the blood.
  • Hyperlucency= Overly black appearance on a radiograph.
  • Hypernephroma= Most common renal cell carcinoma.
  • Hyperparathyroidism= Excessive secretion of parathormone leading to elevated serum levels of calcium and phosphate.
  • Hyperparathyroidism= Oversecretion of the parathyroid hormone, causing calcium to leave bone and enter the bloodstream.
  • Hyperplasia= Abnormal increase in the number of cells composing a tissue or organ.
  • Hypertension= a common, often asymptomatic disorder characterized by elevated blood pressure persistently exceeding 140/90 mm Hg.
  • Hypertension= High blood pressure.
  • Hyperthermia= a higher than normal body temperature. Same as fever or pyrexia.
  • Hyperventilation= a respiratory rate that is greater than that metabolically necessary for pulmonary gas exchange. It is the result of rapid breathing, an increased tidal volume, or a combination of both, and causes excessive intake of oxygen and elimination of carbon dioxide.
  • Hypervolemia= an abnormal increase in the amount of intravascular fluid, particularly in the volume of circulating blood or its components. Same as fluid overload.
  • Hypoactive= Decreased activity.
  • Hypocalciuria= Abnormally low calcium in the urine.
  • Hypodermic= pertaining to the area below the skin, such as a hypodermic injection.
  • Hypoglycemia= a less than normal amount of glucose in the blood, usually caused by administration of too much insulin, excessive secretion of insulin by the islet cells of the pancreas, or dietary deficiency.
  • Hypoparathyroidism= Insufficient secretion of parathormone causing sustained muscular contraction.
  • Hypoplastic kidney= Underdeveloped kidney.
  • Hyporetention=A residue of fixer components remaining on a film after processing.
  • Hypotension= an abnormal condition in which the blood pressure is not adequate for normal perfusion and oxygenation of the tissues. See also shock.
  • Hypotension= Low blood pressure.
  • Hypothalamus= a portion of the diencephalon of the brain. It activates, controls, and integrates the peripheral autonomic nervous system, endocrine processes, and many somatic functions, such as body temperature, sleep, and appetite.
  • Hypothalamus= Activates, controls, and integrates peripheral autonomic nervous system, endocrine system, and somatic functions.
  • Hypovolemia= an abnormally low circulating blood volume; may be caused by hemorrhage or by severe dehydration.
  • Hypoxemia, hypoxia= insufficient oxygenation of the blood.
  • Hypoxia= Deficiency (lack) of oxygen.
  • Hysteresis loss= Results from energy expended as the continually changing AC current magnetizes, demagnetizes, and remagnetizes the core material; also called lagging loss.
  • Hysterosalpingography= a method of producing radiographic images of the uterus and fallopian tubes as part of the diagnosis of abnormalities in the reproductive tract of a nonpregnant woman.
  • I2R loss=  Results from the inherent resistance to current flow that is found in all conductors; power lost from resistance is proportional to the square of current; sometimes called copper loss.
  • I2R= Formula for power in watts, where I=current in amperes, R=resistance in ohms.
  • Iatrogenic= Resulting from the activity of diagnosis or treatment by medical personnel.
  • ICU= abbreviation for intensive care unit.
  • ID plate=Area on the resulting image that indicates the patient and facility’s identification information, procedure completed, and date and time that the procedure was completed.
  • IDC=Insulation Displacement Connector. Type of connector where contact is made to the cable conductor(s) by cutting through the individual conductor’s insulation. The conductor does not need to have its insulation removed prior to connection. Flat cable often uses idcs to simultaneous connect all conductors.
  • Identity= An equation in which all numeric values substituted for the unknown will give a true statement.
  • Idiopathic= Having an unknown cause for underlying disease.
  • IF=Intermediate Frequency.
  • Ileostomy= surgical formation of an opening of the ileum onto the surface of the abdomen, through which fecal matter is expelled.
  • Iliopsoas fat plane=Fat plane that lies within the pelvis medial to the lesser trochanters.
  • Illuminance=The brightness of light projected on a given surface, measured in lux or foot-candles.
  • Image acquisition=Process of collecting x-ray transmission measurements from the patient.
  • Image annotation= software function that allows text or markers to be digitally added to an image.
  • Image Compression=A reduction of the space required to store or time required to transfer a digital image.
  • Image Enhancement=The use of a computer to improve or enhance an image.
  • Image intensification tube= Video camera and monitor used to view fluoroscopic images.
  • Image intensifier= an electronic device used to produce a fluoroscopic image with a low-radiation exposure. A beam of x-rays passing through the patient is converted by a special vacuum tube into a pattern of electrons. The electrons are accelerated and concentrated onto a small fluorescent screen, where they present a bright image, which is generally displayed on a television monitor.
  • Image Intensifier=An electronic device that brightens a fluoroscopic image.
  • Image Inversion=Allows the converting of a negative image (standard radiographic image) into a positive image (meaning a reverse of the negative image where white areas on the negative image are black on the positive image and vice versa).
  • Image Lag=An image persisting on a cathode-ray tube even after termination of radiation.
  • Image Management and Communication System (IMACS)=A computerized system for storing patient images and medical records.
  • Image manager= contains the master database of everything that is in the archive.
  • Image orientation= identification of the top or side of an image.
  • Image receptor (film)= The medium used to capture the radiographic image for recording.
  • Image receptor (IR)=Device that receives the radiation leaving the patient. Conventional radiography uses a screen-film system and computed radiography uses an imaging plate.
  • Image Restoration=A process in digital imaging whereby the final image is displayed.
  • Image sampling= amount of information gathered from pixel storage.
  • Image stitching= process of “sewing” together multiple images to form one continuous image.
  • Image storage= process of sending the digital image to PACS or CD.
  • Image Uniformity=A uniform brightness level throughout the image when visualizing a homogenous phantom.
  • Imaging noise= Background information that the  imaging receptor receives.
  • Imaging plate (IP)=1. Plate used in computed radiography that is coated with a photostimulable phosphor material that absorbs the photons exiting the patient, resulting in the formation of a latent image that is released and digitized before being sent to a computer. 2. Thin flexible sheet of plastic with a photostimulable phosphor layer that is placed inside the computed radiography cassette to record the radiographic image; computed radiography’s image receptor.
  • Imaging plate= thin piece of plastic with several layers of material that capture and store image data.
  • Immediately Dangerous to Life or Health (IDLH)= A level of exposure to airborne contaminants likely to cause (1) death; (2) immediate or delayed permanent adverse health effects; or (3) prevent escape from such an environment. IDLH values are considered a maximum level above which only a highly reliable breathing apparatus providing maximum worker protection is permitted.
  • Immune= Reaction of the body provides a powerful defense against invading organisms.
  • Immunosuppressant= an agent that significantly interferes with the ability of the immune system to respond to antigenic stimulation by inhibiting cellular and humoral immunity.
  • Impedance Match=A condition whereby the impedance of a particular circuit cable or component is the same as the impedance of the circuit, cable, or device to which it is connected.
  • Impedance Matching Sub=A section of transmission line or pair of conductors cut to match the impedance of a load. Also called matching sub.
  • Impedance Matching Transformer=A transformer designed to match the impedance of one circuit to that of another.
  • Impedance, Characteristic=In a transmission cable of infinite length, the ratio of the applied voltage to the resultant current at the point the voltage is applied. Or the impedance which makes a transmission cable seem infinitely long, when connected across the cable’s output terminals.
  • Impedance, High=Generally, the area of 25,000 ohms or higher.
  • Impedance, Low=Generally, the area of 1 through 600 ohms.
  • Impedance=The total opposition that a circuit offers to the flow of alternating current or any other varying current at a particular frequency.
  • In situ= Confined to the site of origin.
  • Incident (unplanned event)= Examples= An occurrence or event, natural or manmade that requires a response to protect life or property. Incidents can include major disasters, emergencies, terrorist attacks, terrorist threats, civil unrest, wild land and urban fires, floods, hazardous materials spills, nuclear accidents, aircraft accidents, earthquakes, hurricanes, tornadoes, tropical storms, tsunamis, war-related disasters, public health and medical emergencies, and other occurrences requiring an emergency response.
  • Incident electron= The electrons from the thermionic cloud that arrive at the anode target.
  • Incident Light=The emitted light from its source before striking the film.
  • Incident=Any occurrence that is not consistent with the routine care of a patient or the normal course of events at a particular facility.
  • Incision= a cut produced surgically by a sharp instrument to create an opening into an organ or space in the body.
  • Inclination = measure of the angle between the horizontal plane and earth’s magnetic field.
  • Incoming-line current The alternating current that is supplied to buildings; usually supplied in three-phase power cycle; also called the mains.
  • Incomplete fracture= Opposite cortex is intact.
  • Incontinence= inability to control urination or defecation.
  • Incontinence= Loss of urinary bladder control.
  • Incorporation= Incorporation refers to the uptake of radioactive materials by body cells, tissues, and target organs such as bone, liver, thyroid, or kidney. In general, radioactive materials are distributed throughout the body based upon their chemical properties. Incorporation cannot occur unless contamination has occurred. Incorporation is also called internal contamination.
  • Incubator= a crib for a newborn that provides security and warmth. A closed incubator may be used for premature infants and those at risk to supply moisture and oxygen while reducing exposure to airborne infection.
  • Indicator=A valid and reliable quantitative process or outcome measure related to one or more dimensions of performance.
  • Indirect acquisition= The radiographer must move the detector between image acquisition and display; a two-part process involving a scintillator (which converts incoming x-ray photons to light) and photodetector (which converts light to an electronic signal).
  • Indirect capture digital radiography= devices that absorb x-rays and convert them into light; the light is then detected by an area-charge-coupled device or thin-film transistor array in concert with photodiodes, and then converted into an electrical signal that is sent to the computer for processing and viewing.
  • Indirect conversion= two-step process in which x-ray photons are converted to light and then the light photons are converted to an electrical signal.
  • Indolent= Causing little or no pain; slow to heal.
  • Induced magnetism = the temporary alignment of the magnetic domains in magnetic material when it is placed near a magnet.
  • Inductance=The property of wire which stores electrical current in a magnetic field around the wire. By coiling wire, the effect can be intensified. It is measured in Henrys.
  • Induction Heating=Heating a conducting material by placing it in a rapidly changing magnetic field. The changing field induces electric currents in the material and losses account for the resultant heat.
  • Induction= The process of electrical fields acting on one another without contact.
  • Induction=The phenomenon of a voltage, magnetic field, or electrostatic charge being produced in an object from the source of such fields.
  • Inductive Crosstalk=Crosstalk resulting from the coupling of the electromagnetic field of one conductor upon another.
  • Inductive reactance= The ability of an alternating current to switch directions, causing the opposing potential difference to induce against the incoming supply of electrons; measured in ohms of resistance.
  • Inert= (of a chemical substance) not taking part in a chemical reaction; (of a medication ingredient) not active pharmacologically; serving only as a bulking, binding, or sweetening agent or other excipient in a medication.
  • Infarction= Death of tissue because of interruption of the normal blood supply.
  • Infectious gastritis= Inflammation of the stomach lining caused by a microorganism.
  • Infectious mononucleosis= an acute infection caused by the Epstein-Barr virus. It is characterized by fever, sore throat, swollen lymph glands, atypical lymphocytes, splenomegaly, hepatomegaly, abnormal liver function, and bruising. The disease is usually transmitted by droplet infection but is not highly or predictably contagious.
  • Inferior (infero-)=Refers to a structure within the patient’s torso that is situated closer to the feet; used when comparing the locations of two structures. The symphysis pubis is inferior to the iliac crest.
  • Infiltrating= Spreading into surrounding tissue.
  • Infiltration= the process whereby a fluid passes into the tissues, such as when a local anesthetic is administered or an intravenous infusion leaks from a vein.
  • Inflammation, inflammatory= the protective response of body tissues to irritation, infection or injury, characterized by warmth, redness, swelling, and pain.
  • Inflammation= Initial response of body tissue to local injury.
  • Influenza= highly contagious infection of the respiratory tract caused by a myxovirus and transmitted by airborne droplet contamination.
  • Informed consent= permission obtained from a patient to perform a specific test or procedure. Informed consent is required before performing most invasive procedures and before admitting a patient to a research study. The document used must be written in a language understood by the patient and be dated and signed by the patient and at least one witness.
  • Infraorbital=Below the orbits.
  • Infraorbitomeatal line (IOML)=Imaginary line connecting the inferior orbital margin and external acoustic opening.
  • Infundibulum= Funnel-shaped organ or passage.
  • Infusion= the passive introduction of a substance (fluid, drug, or electrolyte) into a vein or between tissues, as by gravitational force; slow and/or prolonged intravenous delivery of a drug or fluids.
  • Ingest, ingestion= to take substances into the body through the mouth.
  • Ingestion= 1) the act of swallowing; 2) in the case of radionuclides or chemicals, swallowing radionuclides or chemicals by eating or drinking.
  • Inguinal= Pertaining to the groin.
  • Inhalation= 1) the act of breathing in; 2) in the case of radionuclides or chemicals, breathing in radionuclides or chemicals.
  • Inherent filtration= Results from the composition of the tube and housing.
  • Inpatient= a patient who has been admitted to a hospital or other health care facility for at least an overnight stay.
  • Input=A signal (or power) which is applied to a piece of electric apparatus or the terminals on the apparatus to which a signal or power is applied.
  • Input=Information or knowledge necessary to achieve the desired outcome.
  • Insertion Loss=A measure of the attenuation of a cable and/or component(s) by determining the output of a system before and after the device is inserted into the system.
  • Insidious= Developing in a slow or unapparent manner; more dangerous than seems evident (e.g., an insidious disease).
  • Insufficiency= Less than the normal amount.
  • Insulation Displacement Connector (IDC)=A mass termination connector for flat cable with contacts that displace the conductor insulation to complete termination.
  • Insulation Stress=The molecule separation pressure caused by a potential difference across an insulator. The practical stress on insulation is expressed in volts per mil.
  • Insulator= A material that inhibits electron flow.
  • Insulin= a naturally occurring hormone secreted by the beta cells of the islets of Langerhans in the pancreas in response to increased levels of glucose in the blood. Also, a medication administered to patients who lack sufficient natural insulin.
  • Insulinoma= Hormone-secreting neoplasm most frequently in the tail of the pancreas, usually benign .
  • Integral dose= The total amount of energy imparted to matter; the product of dose and the mass over which the energy is imparted.
  • Integrated imaging= Requires software to fuse to imaging modalities.
  • Intensification factor= The most accurate factor that measures the speed or sensitivity of an intensifying screen; a measurement of the amplification of the image that occurs due to the screen’s ability to convert x-ray photons to light.
  • Intensification Factor=A measurement of intensifying screen speed.
  • Intensifying screen= Device used to amplify the incoming x-ray beam and reduce patient radiation dose.
  • Intercostal space= the space between two ribs.
  • Interface=The region where two systems or a major and a minor system meet and interact with each other.
  • Interference=Disturbances of an electrical or electromagnetic nature that introduce undesirable responses into other electronic equipment.
  • Interferon= a natural cellular protein formed when cells are exposed to a virus or another foreign particle of nucleic acid. Also, a medication made from natural interferons that directs the immune system’s attack on viruses, bacteria, tumors, and other foreign substances that may invade the body, such as the hepatitis C virus and certain types of cancer.
  • Interiliac line=Imaginary line connecting the iliac crests.
  • Intermalleolar line=Imaginary line drawn between the medial and lateral malleoli.
  • Intermammillary line= a horizontal anatomic line drawn between the nipples.
  • Intermediate Frequency=A frequency to which a signal is converted for ease of handling. Receives its name from the fact that it is an intermediate step between the initial and final conversion or detection stages.
  • Intermittent injection port= a small adapter with a diaphragm that is attached to an IV catheter when more than one injection is anticipated. Same as heparin lock or saline lock.
  • Intern= a physician in the first postgraduate year, learning medical practice under supervision before beginning a residency program or practice.
  • Internal (medial) rotation=Act of turning the anterior surface of an extremity inward or toward the patient’s torso midline.
  • Internal exposure= exposure to radioactive material taken into the body.
  • Internal fixation= Surgically placed metal plates and screws, wires, rods, or nails to maintain reduction.
  • Interpupillary line=Imaginary line connecting the outer corners of the eyelids.
  • Interstitial pneumonia= Inflammatory process predominantly involving the walls and lining of the alveoli, its septa, and interstitial supporting structures.
  • Intima= Innermost layer of an organ or blood vessel.
  • Intradermal= within the dermis layer of the skin.
  • Intraluminal= Within the empty space (lumen) of a hollow viscus.
  • Intramembranous ossification= Bone formation from connective tissue.
  • Intramural= Within the wall of an organ.
  • Intramuscular= within muscle tissue.
  • Intraperitoneal air=Presence of free air in the abdominal cavity.
  • Intrathecal= pertaining to a structure, process, or substance within a sheath, such as within the spinal canal.
  • Intrathoracic kidney= Kidney located in the thoracic cavity.
  • Intrauterine device (IUD)= a contraceptive device. It consists of a bent strip of radiopaque plastic with a fine monofilament tail and is placed within the uterus.
  • Intravascular= within a blood vessel.
  • Intravenous (IV)= pertaining to the inside of a vein, as of a thrombus or an injection, infusion, or catheter.
  • Intrinsic asthma= Reaction to exercise, heat or cold exposure, and emotional upset.
  • Intrinsic rhythm= Specialized pacemaker cells in the sinoatrial node that initiate impulses at regular intervals.
  • Intrinsic= Belonging to the real nature of a thing.
  • Intubate, intubation= passage of a tube into a body aperture, specifically the insertion of a breathing tube through the mouth or nose into the trachea to ensure a patent airway for the delivery of anesthetic gases or oxygen or both.
  • Invasive= characterized by a tendency to spread, infiltrate, and intrude. Invasive procedures involve penetration of the body wall (for example, surgery or angiography).
  • Inverse square law= Law of electrostatics that states the force between two charges is directly proportional to the product of their magnitudes and inversely proportional to the square of the distance between them.
  • Inverse square law= the relationship that states that electromagnetic radiation intensity is inversely proportional to the square of the distance from a point source.
  • Inverse square law=Law that states that radiation intensity is inversely proportional to the square of its distance from the x-ray source.
  • Inverse variation= When two quantities are multiplied, their product is a constant.
  • Inversion time (TI)= The time between a 180-degree pulse and a 90-degree inversion pulse in an inversion recovery pulse sequence.
  • Inversion=Act of turning the plantar foot surface as far medially as the ankle will allow.
  • Involuntary motion=Movement that the patient cannot control.
  • Iodinated= refers to substances to which iodine has been added, especially types of contrast media prepared with iodine compounds, which absorb radiation to a greater degree than blood or soft tissues and therefore produce a more clearly visible white or light shadow on the radiographic image.
  • Iodine= a nonmetallic solid element. There are both radioactive and non-radioactive isotopes of iodine. Radioactive isotopes of iodine are widely used in medical applications. Radioactive iodine is a fission product and is the largest contributor to people’s radiation dose after an accident at a nuclear reactor.
  • Ion Chamber=A type of gas-filled radiation detector.
  • Ion= a charged particle, an atom or group of atoms that has acquired an electrical charge through the gain or loss of one or more electrons.
  • Ion= an atom that has fewer or more electrons than it has protons, causing it to have an electrical charge and, therefore, be chemically reactive.
  • Ion= An atom that has gained or lost an electron.
  • Ionic solution= Charged particles dissolved within a solution.
  • Ionic= pertaining to a compound that separates into charged particles in solution.
  • Ionization chamber device= An automatic exposure control device used to terminate the exposure after a desired exposure has been reached.
  • Ionization chamber=Chamber in the AEC system that collects radiation. For adequate radiographic density to result, the appropriate chamber must be selected for the part being imaged.
  • Ionization Voltage=The potential at which a material ionizes. The potential at which an atom gives up an electron.
  • Ionization=  the process of adding one or more electrons to, or removing one or more electrons from, atoms or molecules, thereby creating ions. High temperatures, electrical discharges, or nuclear radiation can cause ionization.
  • Ionization= The process of adding or removing an electron from an atom.
  • Ionization=The formation of ions. Ions are produced when polar compounds are dissolved in a solvent and when a liquid, gas, or solid is caused to lose or gain electrons due to the passage of an electric current.
  • Ionize, ionization= to separate or change into ions (charged particles).
  • Ionizing radiation= any radiation capable of displacing electrons from atoms, thereby producing ions. High doses of ionizing radiation may produce severe skin or tissue damage.
  • Ipsilateral= Relating to the same side (antonym: contralateral)
  • IR Drop=The designation of a voltage drop in terms of current and resistance. See also Voltage Drop.
  • Iridium-192= A gamma-ray emitting radioisotope used for gamma radiography. The half-life is 73-83 days.
  • Iron = a magnetic metal that is one of the most common elements on earth and in the universe.
  • Irradiation= exposure to radiation.
  • Irrigate, irrigation= to flush with a fluid, usually with a slow steady pressure on a syringe plunger. It may be done to cleanse a wound or to clear tubing.
  • Irritable bowel syndrome= Refers to several conditions that have an alteration in intestinal motility.
  • IRS=Ignition radiation suppression.
  • Ischemia= a decreased supply of oxygenated blood to a body organ or part.
  • Ischemia= Lack of blood supply in an organ or tissue.
  • Islands of Langerhans= Another name for islets of Langerhans.
  • Isoechoic= Structures that have the same echogenicity.
  • Isolation=The ability of a circuit or component to reject interference, usually expressed in db.
  • Isotope= a nuclide of an element having the same number of protons but a different number of neutrons.
  • Isotope= Atoms that have the same number of protons in the nucleus but differ in the number of neutrons.
  • Jefferson’s fracture= Comminuted fracture of the ring of the atlas involving both the anterior and posterior arches.
  • Joint effusion=Escape of fluid into the joint.
  • Jones fracture= Transverse fracture at the base of the 5th metatarsal.
  • Juxtaarticular= Adjacent to a joint.
  • Kb=Kilobyte.
  • K-edge filter= The use of two or more materials to complement one another in their absorbing abilities; also known as compound filters.
  • K-edge=The binding energy of K-shell electrons.
  • Kerma= Kinetic energy released in matter; the energy imparted directly to electrons per unit mass.
  • Kerma= the initial kinetic energy of the primary ionizing particles (photoelectrons, Compton electrons, positron/negatron pairs from photon radiation, and scattered nuclei from fast neutrons) produced by the interaction of the incident uncharged radiation, per unit mass of interacting medium. Unit of measure is gray. See also air kerma.
  • Kerma=An acronym for kinetic energy released in matter, it measures the amount of kinetic energy that is released into particles of matter (such as electrons created during Compton and photoelectric interactions) from exposure to x-rays.
  • Ketoacidosis= an acidic condition of the blood accompanied by an accumulation of ketones, resulting from extensive breakdown of fats because of faulty carbohydrate metabolism.
  • Kev=1000 electron volts.
  • Kilo=One thousand.
  • Kilogram= The standard unit of mass, abbreviated as kg.
  • Kiloton (Kt)= the energy of an explosion that is equivalent to an explosion of 1,000 tons of TNT. One kiloton equals 1 trillion (1012) calories.
  • Kilovolt (kv), kilovoltage= measure of electrical potential, 1000 volts.
  • Kilovoltage peak (kvp)= potential difference measured at the peak of the electrical cycle. An x-ray control setting that determines the penetrating power of the x-ray beam.
  • Kilowatt Rating=A rating of power output for x-ray generators.
  • Kinetic= energy The energy of motion.
  • K-shell absorption edge= When the incident x-ray photons match the K-shell binding energy of the phosphor, there is an increase in characteristic production within the screen.
  • K-shell= The orbital shell closest to the nucleus.
  • Kv=Kilovolt (1000 volts).
  • Kva=Kilo Volt=ampere. One thousand volt=amperes (VA). See also VA.
  • Kvp= kilovoltage peak
  • Kvp=Kilovoltage potential.
  • Kw=Kilowatt.
  • Kyphosis, kyphotic= posterior curvature of the spine, characteristic of the thoracic spinal segments. When abnormally exaggerated, kyphosis results in protrusion of the upper back.
  • Kyphosis= Anterior convexity in the curvature of the thoracic spine, sacrum, and coccyx, as viewed from the side.
  • Kyphosis=Excessive posterior convexity of the thoracic vertebrae.
  • Laceration= a torn, jagged wound.
  • Lambda= The Greek letter that represents the measurement of a wavelength.
  • Laparoscope= a type of fiberoptic instrument consisting of an illuminated tube with an optical system. It is inserted through the abdominal wall for examining the peritoneal cavity.
  • Larmor frequency= In a static homogenous magnetic field, all protons in a nucleus of a given type element will rotate with exactly the same frequency.
  • Laryngectomy= surgical removal of the larynx performed to treat cancer of the larynx.
  • Larynx, laryngeal= the organ of voice that is part of the air passage connecting the pharynx with the trachea.
  • Laser film= A type of film that is directly exposed by the laser used in the imaging camera.
  • Laser= amplification of stimulated emission of radiation, a device that creates and amplifies a narrow, intense beam of coherent light.
  • Latensification=The increase in sensitivity of a film after it has been exposed to light or ionizing radiation (such as in a cassette during a radiographic examination) so that it can be as much as two to eight times more sensitive to subsequent exposure as an unexposed film (depending on the type of emulsion).
  • Latent image= the unobservable image stored in the silver halide emulsion of film; it is made visible by processing.
  • Latent Image=An invisible image present after exposure but before processing.
  • Latent period= the time between exposure to a toxic material and the appearance of a resultant health effect.
  • Lateral (latero-)=Refers to the patient’s sides; used to express something that is directed or situated away from the patient’s median plane or to express the outer side of an extremity: The kidneys are lateral to the vertebral column. Or, Place the IR against the lateral surface of the knee.
  • Lateral mortise=Talofibular joint.
  • Lateral position=Refers to positioning of the patient so that the side of the torso or extremity being imaged is placed adjacent to the IR. When a lateral position of the torso, vertebrae, or cranium is defined, the term right or left is also included to state which side of the patient is placed closer to the IR. The patient was in a left lateral position when the chest image was taken.
  • Lateral Resolution=A measure of how close two reflectors can be to one another perpendicular to the beam axis and still be distinguished as separate.
  • Latitude The range of exposures that will produce densities within the diagnostic range.
  • Latitude= amount of error that can be made in exposure factor choice and still result in the capture of a quality image.
  • Lauenstein method=Position in which the affected leg is flexed and abducted and the patient is rotated toward the affected hip as needed to position the femur against the imaging table; this will demonstrate a lateral hip projection with an unforeshortened proximal femur.
  • Law of isometry=Used to minimize shape distortion when imaging long bones when the bone and IR cannot be positioned parallel. The law of isometry indicates that the central ray should be set at half the angle formed between the bone and IR.
  • Law of Reciprocity=Law stating that the amount of x-ray intensity should remain constant at a specific milliampere-second value despite the milliampere and time combination.
  • Laws of electrostatics= Rules relating how objects are electrified.
  • Lead (Pb)= a heavy metal. Several isotopes of lead, such as Pb-210 which emits beta particles, are in the uranium decay chain.
  • Lead federal agency (LFA)= the federal agency that leads and coordinates the emergency response activities of other federal agencies during a nuclear emergency. After a nuclear emergency, the Federal Radiological Emergency Response Plan.
  • Leakage radiation= Any photons that escape from the housing except at the port.
  • Leakage=The undesirable passage of current over the surface of or through an insulator.
  • Left-to-right shunt= Diversion of blood from the left side of the heart to the right through a septal defect.
  • Lesion= a wound, injury, or pathological change in body tissue. Also, any visible, local abnormality of the tissues of the skin, such as a wound, sore, rash, or boil. A lesion may be described as benign, cancerous, gross, occult, primary or secondary.
  • Lethal dose (50/30)= the dose of radiation expected to cause death within 30 days to 50% of those exposed without medical treatment. The generally accepted dose is about 400 rem received over a short period of time.
  • Leukemia= a broad term given to a group of malignant diseases affecting the bone marrow.
  • Leukocyte reduction= a process used to filter and remove white blood cells from whole blood before transfusion. Leukocytes are removed from blood because they provide no benefit to the recipient but may carry bacteria and viruses to the recipient. Patients who receive blood that has not been leuko-reduced may have adverse effects, including fever with chills; alloimmunization, an immune system reaction that can compromise a later transfusion; and the transmission of viruses, including cytomegalovirus, which can be dangerous for low-birth weight infants and to immunosuppressed patients.
  • Leukocytosis= Abnormal amount of white blood cells in the blood.
  • Level of consciousness (LOC)= degree of cognitive function involving arousal mechanisms of the reticular formation of the brain.
  • Level of Expectation=A pre-established level of performance applied to a specific indicator.
  • Level= image manipulation parameter that changes screen image contrast usually through the use of a mouse.
  • Level=A measure of the difference between a quantity or value and an established reference.
  • LF=Low frequency.  International Telecommunication Union designation for the 30=300 khz band of frequencies.
  • Libel= a false accusation written, printed, or typewritten, or presented in a picture or a sign that is made with malicious intent to defame the reputation of a person who is living or the memory of a person who is dead, resulting in public embarrassment, contempt, ridicule, or hatred.
  • Lidocaine= a local anesthetic agent, also given intravenously to treat ventricular tachycardia.
  • Like terms= Terms (numbers) with identical literal factors (usually noted by a letter).
  • Line Drop=A voltage loss occurring between any two points in a power or transmission line. Such loss, or drop, is due to the resistance, reactance, or leakage of the line. See also Voltage Drop and IR Drop.
  • Line Equalizer=A reactance (inductance and/or capacitance) connected in series with a transmission line to alter the frequency=response characteristics of the line.
  • Line Focus Principle=A principle stating that the effective focal spot always appears smaller than the actual focal spot because of the anode angle.
  • Line Level=Refers to the output voltage level of a piece of electronic equipment. Usually expressed in decibels (e.g.. 0 dbv).
  • Line of gravity= an imaginary line that extends from the center of gravity to the base of support.
  • Line pairs per millimeter (Ip/mm)= Measurement of recorded detail, sharpness, and resolution; the minimum size and space between objects that can be visualized on the final image.
  • Line spread function (LSF)= Measurement of recorded detail, sharpness, and resolution; the ability of a film/screen system to accurately measure the boundaries of an image.
  • Line Spread Function=A graphic indication of image resolution.
  • Line Voltage=The value of the potential existing on a supply or power line.
  • Linear grid= A grid with lead strips running in only one direction.
  • Linear skull fracture= Jagged or irregular sharp lucent line.
  • Linear Tomography=A type of conventional tomography whereby the x-ray source and image receptor undergo reciprocal motion in a straight line.
  • Linearity=Sequential increases in milliampere-seconds should produce the same sequential increase in exposure rate.
  • Line-focus principle= Used to reduce the effective area of the focal spot.
  • Lines of flux= The force fields that are created when magnetic dipoles orient to create a magnet; also called lines of force and magnetic field.
  • Lines of force The force fields that are created when magnetic dipoles orient to create a magnet; also called lines of flux and magnetic field.
  • Lipoma= Tumor composed of fat.
  • Lipoprotein= a conjugated protein in which fats or oils form an integral part of the molecule.
  • Liquid Crystal Display (LCD)=Flat-panel display form for monitors.
  • Lithotripsy= a procedure for crushing and eliminating a calculus in the renal pelvis, ureter, bladder, or gallbladder.
  • Load=A device that consumes power from a source and uses that power to perform a function.
  • Local area network (LAN)=  small area networked with a series of cables or wireless access points so that the computers can share information and devices on the same network.
  • Local radiation injury (LRI)= acute radiation exposure (more than 1,000 rads) to a small, localized part of the body. Most local radiation injuries do not cause death. However, if the exposure is from penetrating radiation (neutrons, x-rays, or gamma rays), internal organs may be damaged and some symptoms of Acute Radiation Syndrome (ARS), including death, may occur. Local radiation injury invariably involves skin damage, and a skin graft or other surgery may be required.
  • Localized ileus= Isolated distended loop of small or large bowel.
  • Locational Effect=A variation in film quality caused by the sensitometric test film being inserted in different portions of the feed tray.
  • Lodestone = naturally magnetic rock that is made up of the mineral magnetite.
  • Logarithm of the median exposure (LGM)=  term used by agfa to express exposure to the imaging plate.
  • Longitudinal foreshortening=Long axis of the structure appears disproportionately shorter on the image than the short axis.
  • Longitudinal or lengthwise (LW)=Refers to the long axis of the anatomic structure or object being discussed. A longitudinal axis on a 14- × 17-inch (35- × 43-cm) IR would parallel the IR’s longer (17-inch or 43-cm) length. The longitudinal axis of a patient’s thorax would parallel the midsagittal plane. To position the IR LW with the patient means to align the IR’s longitudinal axis with the patient’s longitudinal axis.
  • Look-up table (LUT)=  reference histogram of the luminance values derived during image acquisition.
  • Look-Up Table (LUT)=A table used to assign (transform) digital data into image brightness values.
  • Lookup table (LUT)=Histogram of the brightness values of the ideal image. It is used as a reference to evaluate the raw data of similar images and automatically rescales their values when needed to match those in the LUT.
  • Loop of Henle= U-shaped portion of the renal tubule.
  • Lordosis, lordotic= anterior curvature of the spine, characteristic of both the cervical and lumbar spinal segments.
  • Lordosis= Anterior concavity in the curvature of the lumbar and cervical spine, as viewed from the side.
  • Loss Potential=Any activity that costs a facility either money or its reputation.
  • Loss=Energy or signal lost without accomplishing useful work.
  • Lossy=Having high losses resulting in efficiency.
  • Low Frequency=International Telecommunication Union designation for the 30=300 khz band of frequencies.
  • Low-Contrast Resolution=Performance variable measuring the ability to image structures of similar density.
  • Low-level waste (LLW)= radioactively contaminated industrial or research waste, such as paper, rags, plastic bags, medical waste, and water-treatment residues. It is waste that does not meet the criteria for any of three other categories of radioactive waste= spent nuclear fuel and high-level radioactive waste; transuranic radioactive waste; or uranium mill tailings. Its categorization does not depend on the level of radioactivity it contains.
  • Low-pass filtering= Amplifies or deletes all but the low frequencies.
  • Low-pass filtering= result of averaging each pixel’s frequency with surrounding pixel values to remove high frequency noise; the result is a reduction of noise and contrast; useful for viewing small structures such as fine bone.
  • Lumbar puncture (LP)= the introduction of a hollow needle and stylet into the subarachnoid space of the lumbar part of the spinal canal. Same as spinal tap.
  • Lumen (plural, lumina)= the interior canal of an organ or catheter.
  • Luminance=The amount of luminous intensity emitted by a source of light.
  • Luminescence= The ability of a material to emit light in response to excitation.
  • Luminescence=The emission of light resulting from x-rays exiting the patient, which energize the phosphor crystals. It can occur by one of two different processes, fluorescence or phosphorescence.
  • Lyme disease= an acute recurrent inflammatory infection transmitted by a tickborne spirochete, Borrelia burgdorferi.
  • Lymphangitic= Spread by means of the lymphatic system.
  • Lymphatic leukemia= Malignancy of the lymph nodes in which the lymphocytes are the only white blood cells to increase.
  • Lymphatic spread= Malignant cells carried through the lymphatic system.
  • Lymphocyte= small agranulocytic leukocyte (white blood cell) originating from fetal stem cells and developing in the bone marrow.
  • Lymphoma= neoplasm consisting of lymphoid tissue that originates in the reticuloendothelial and lymphatic systems. It is usually malignant but in rare cases may be benign.
  • Lymphoma= Neoplastic disorder of lymphoid tissue.
  • Lysozyme= an enzyme found in tears and other secretions that acts to destroy some foreign organisms.
  • Lytic= Destructive.
  • M theory= Electrons and quarks may not be particles, but instead may be extremely small loops of rapidly vibrating string-like matter.
  • Ma=milliampere (one=thousandth of an ampere).
  • Mach effect= Each time the eye sees a change in density, there is a change in the intensity of the impulses sent to the brain.
  • Magnet= An object that exhibits a uniformly strong magnetic field.
  • Magnetic dipole= Groups of atoms with their net magnetic field moving in the same direction; also know as magnetic domains.
  • Magnetic disk storage= short-term magnetic disk storage, usually found in arrays (raid).
  • Magnetic domain = small magnetized regions of a magnetic surface.
  • Magnetic domain= Groups of atoms with their net magnetic field moving in the same direction; also know as magnetic dipoles.
  • Magnetic field = area of force that exists around a magnet or a current=carrying conductor.
  • Magnetic field= The force fields that are created when magnetic dipoles orient to create a magnet; also called lines of flux and lines of force.
  • Magnetic resonance imaging (MRI)= a noninvasive computerized diagnostic modality that uses a magnetic field and pulses of radio waves to produce images on a computer monitor.
  • Magnetic resonance imaging (MRI)= A strong magnet producing radiofrequencies at specified intervals and receiving a return signal to produce an image.
  • Magnetic resonance= The effect that occurs when an electromagnetic RF field that is alternating, or resonating, at the Larmor frequency is applied in addition to the static field, causing protons to alternate from parallel to antiparallel.
  • Magnetic storm = a large particle disturbance of earth’s magnetic field due to solar flares.
  • Magnetism = the force of attraction between an object and a magnet, which pulls the object toward the magnet.
  • Magnetite = mineral that is naturally magnetic and mostly made of iron oxide.
  • Magnetometer = instrument that measures the strength and direction of magnetic forces.
  • Magneto-optical disk (MOD)=  very similar to a CD or DVD in that it is read optically with a laser, but the disk itself is housed within a plastic cartridge.
  • Magnetosphere = earth’s magnetic field.
  • Magnification= enlargement of an image in all dimensions without loss of sharpness.
  • Magnification=Electronic digital zoom with software manipulation that can reduce the need to take additional magnification views, as with film/screen mammography.
  • Magnification=Proportionately increasing or enlarging both axes of a structure. The gonadal contact shield is magnified on the image if it is placed on top of the patient.
  • Main circuit= Supplies the x-ray tube with properly modified power.
  • Main switch= The switch that generates the power to the x-ray tube.
  • Mains The alternating current that is supplied to buildings; usually supplied in three-phase power cycle; also called the incoming-line current.
  • Major motor seizure= a seizure characterized by loss of consciousness and a repeated rigid arching of the back alternating with periods of relaxation. Same as grand mal or tonic-clonic seizure.
  • Malabsorption disorder= Multitude of conditions in which there is defective absorption in the small bowel.
  • Malaise= Vague feeling of physical discomfort or uneasiness, as early in an illness.
  • Malaria= a severe infectious illness caused by one or more of at least four species of the protozoan genus Plasmodium. The disease is transmitted from human to human by a bite from an infected Anopheles mosquito. Malarial infection can also be spread by blood transfusion from an infected patient or by the use of an infected hypodermic needle.
  • Mallory-Weiss syndrome= Subsequent inflammation of the distal esophagus due to a laceration associated with bleeding and mediastinal penetration caused by severe retching and vomiting.
  • Malpractice= professional negligence that is the proximate cause of injury or harm to a patient, resulting from a lack of professional knowledge, experience, or skill that can be expected in others in the profession or from a failure to exercise reasonable care or judgment in the application of professional knowledge, experience, or skill.
  • Mammary line=Imaginary line connecting the nipples.
  • Mammogram, mammography= an x-ray image/examination of the soft tissues of the breast to allow identification of various benign and malignant neoplastic processes.
  • Mammography Quality Standards Act (MQSA)=Federal legislation mandating quality standards for all mammographic procedures.
  • Mammography unit= Specialized radiography equipment for studies and imaging of the breast tissues.
  • Mammography= X-ray examination of the breast.
  • Manifest Image=The final visible image.
  • Manometer= a device for measuring the pressure of a fluid, consisting of a tube marked with a scale and containing a relatively incompressible fluid, such as mercury.
  • Manual send= computer function that allows images to be sent to specified reading stations.
  • Marrow= Hollow, tubelike structure within the diaphysis.
  • Mas= milliamperage seconds
  • Mask= The process of modifying pixel values by a mathematical formula; also referred to as convolution.
  • Masking= Indicates the frequencies that have been suppressed during the filtering process.
  • Mass= The quantity of matter contained in an object.
  • Mast cell= Connective tissue containing large basophilic granules that contain heparin, serotonin, bradykinin, and histamine, which are released in response to injury or infection.
  • Mastectomy= surgical removal of one or both breasts, usually to remove a malignant tumor. It may include breast tissue, chest muscle, and axillary lymph nodes.
  • Mastication= Chewing.
  • Matrix A= square series of boxes that gives form to the image
  • Matrix Size=The number of pixels allocated to each linear dimension in a digital image.
  • Matrix= Basic material from which a substance (such as tissue) develops.
  • Matrix= rectangular or square table of numbers that represent the pixel intensity to be displayed on the monitor.
  • Matrix=Columns and rows of pixels (array) that divide a digital pixel.
  • Mean Computed Tomography Number=Average pixel value calculated by dividing the total computed tomography value by the total number of pixels in a sample.
  • Mean=The average set of observations.
  • Mechanical energy= The result of the action of machines or physical movement; can be potential or kinetic.
  • Media into vessels for radiographic studies.
  • Medial (medio-)=Refers to the patient’s median plane; used to express something that is directed or situated toward the patient’s median plane or to express the inner side of an extremity. The sacroiliac joints are medial to the anterior superior iliac spines (asiss). Or, Place the IR against the medial surface of the knee.
  • Median=A point on a scale of measurement above which are exactly one half of the values and below which are the other half of the values.
  • Medication pump= a pump that automatically delivers measured amounts of drugs through an intravenous catheter.
  • Medulla= Inner substance of a bone (bone marrow) or an internal organ (kidney, adrenal gland).
  • Medullary carcinoma= Soft malignant neoplasm of the epithelium that contains little or no fibrous tissue.
  • Medullary cavity= Hollow, tubelike structure within the diaphysis
  • Medulloblastoma= Poorly differentiated malignancy consisting of tightly packed spongioblastic and neuroblastic cells.
  • Megahertz (mhz)= One million waves per second.
  • Megahertz (mhz)=Unit of frequency equal to one million hertz.
  • Megaton (Mt)= the energy of an explosion that is equivalent to an explosion of 1 million tons of TNT. One megaton is equal to a quintillion (1018) calories.
  • Memory= used to store information being currently processed within the central processing unit.
  • Menarche= Commencement of the cyclic menstrual function.
  • Meninges= Three membranes covering the brain and spinal cord.
  • Meningitis= any infection or inflammation of the membranes covering the brain and spinal cord.
  • Meningitis= Inflammation of the coverings of the brain and spinal cord.
  • Meningocele= Protrusion of the meninges through the skin.
  • Menopause= Cessation of the menstrual cycle.
  • Menstrual phase= Menstruation occurs, the final phase of the three.
  • Mentomeatal line=Imaginary line connecting the chin with the external ear opening.
  • Mesentery= Peritoneal folds that attach the small and large bowel to the back wall of the peritoneal cavity.
  • Mesh topology= network that has multiple pathway interconnecting devices and networks.
  • Mesothelioma= Tumor that develops from the surface of the pleura, pericardium, or peritoneum.
  • Metabolism= the aggregate of all chemical processes that take place in living organisms, resulting in growth, generation of energy, elimination of wastes, and other body functions as they relate to the distribution of nutrients in the blood after digestion.
  • Metabolite= a substance produced by metabolic action or necessary for a metabolic process.
  • Metabolize= to change physically and chemically as a result of body processes.
  • Metallic conductor= The most common pathway for the movement of electrical current (e.g., copper).
  • Metallic replacement= A fixer recovery unit in which the fixer acid breaks down the iron in a steel screen or in steel wool and displaces it with silver.
  • Metallic Replacement=A method of silver recovery from used fixer solution.
  • Metaphysis= Wider part at the end of the shaft of a long bone, adjacent to the epiphyseal plate; located between the epiphysis and the diaphysis.
  • Metastasis= Spread of disease to another organ or tissue in the body.
  • Meter= The standard unit of length, abbreviated as m.
  • Mfd=Microfarad (one=millionth of a farad). Modern abbreviation is uf (lower case Green mu followed by F).
  • Mho=The unit of conductance equal to the reciprocal of the unit of resistance (ohm).
  • Mhz=Megahertz (see also).
  • Microbe, microbial= a microorganism, pertaining to a living organism too small to be seen by the naked eye.
  • Microbial dilution= the process of reducing the total number of microorganisms, which is accomplished at three levels: cleanliness measures, disinfection, and sterilization.
  • Microcephaly= Abnormally small head in relation to the body with associated underdevelopment of the brain.
  • Microfarad=One=millionth of a farad (uf, ufd, mf, and mfd are common abbreviations).
  • Micromicrofarad=One=millionth of a microfarad (uuf, uufd, mmf, mmfd are common abbreviations). Modern usage is picofarad (pf).
  • Microorganism= any tiny, usually microscopic, entity capable of carrying on living processes.
  • Micturate= Act of urinating.
  • Midbrain= Major portion of the brainstem between the forebrain and hindbrain.
  • Midcoronal plane=Imaginary plane that passes through the body from side to side and divides it into equal anterior and posterior sections or halves.
  • Midsagittal or median plane=Imaginary plane that passes through the body anteroposteriorly or posteroanteriorly and divides it into equal right and left sections or halves.
  • Milliamperage (ma)= A measurement of x-ray tube current—the number of electrons crossing the tube from cathode to anode per second.
  • Milliamperage-second (mas)= The product of tube current and exposure time.
  • Milliampere seconds (mas)= the product obtained by multiplying the electric current in milliamperes by the exposure time in seconds. The mas is indicative of the total quantity of radiation involved in an exposure and determines the density of the radiographic image.
  • Milliampere, milliamperage (ma)= a unit of electric current that is one thousandth of an ampere. Unit used to measure the rate of current flow in an x-ray tube. It is used to describe the exposure setting of a radiography machine that determines the rate at which x-rays are produced.
  • Milliampere-second timer= A device used in falling load generators and some capacitor units to monitor the product of ma and time on the secondary side of the high-voltage step-up transformer.
  • Mineralocorticoids= Regulate salt and water balance by controlling sodium retention and potassium excretion by the kidneys.
  • Minification gain= Resulting from the same number of electrons that were produced at the large input screen being compressed into the area of the small output screen.
  • Minification Gain=An increase in brightness with image intensifier tubes as a result of the difference in size between the input and output phosphors.
  • Minimum reaction (or response) time= The length of time necessary for the AEC to respond to the radiation and for the generator to terminate the exposure.
  • Minimum response time= The length of time necessary for the AEC to respond to the ionization and send a signal to terminate the exposure.
  • Minimum response time=Shortest exposure time to which the AEC can respond and still produce an image.
  • Miscible= able to be mixed or blended with another substance.
  • Misdemeanor= a criminal offense that is considered less serious than a felony and carries a lesser penalty, usually a fine or imprisonment for less than 1 year.
  • Mission statement= the role of an organization, hospital, or health care facility stated in a one- or two-paragraph declaration of the institution’s basic philosophy and primary goals. This statement provides guidance for the decisions that govern the activities of the organization or facility.
  • Mitosis, mitotic= a type of cell division that occurs in somatic cells and results in the formation of two genetically identical daughter cells containing the diploid number of chromosomes characteristic of the species.
  • Mitral valve= Bicuspid valve situated between the left atrium and ventricle.
  • Mixing= The period of film production in which the
  • Mixture= The combination of two or more substances.
  • Mobile system= A type of radiography equipment that can be brought to the patient anywhere the patient may be.
  • Mobile X-Ray Generator=A smaller-size x-ray generator mounted on wheels that can be transported to various locations.
  • Mode=The one value that occurs with the most frequency.
  • Modulation transfer function (MTF)= Measurement of recorded detail, sharpness, and resolution; measures the resolving ability of a film/screen combination.
  • Modulation transfer function= ability of a system to record available spatial frequencies.
  • Modulation Transfer Function=A graphic or numeric indication of image resolution.
  • Modulation=Altering the characteristics of a carrier wave to convey information. Modulation techniques include amplitude frequency, phase, plus many other forms of on=off digital coding.
  • Moiré grid artifact=Wavy line artifact that occurs when a stationary grid is used in computed radiography and the imaging plate is placed in the plate reader so that the grid’s lead strips align parallel with the scanning direction.
  • Moiré= grid line or image noise pattern that occurs when either the alignment of the grid to the laser scan direction is incorrect or when spatial frequency is greater than the nyquist frequency; a wraparound image will result.
  • Mold= fungus that occurs in long, branched, filament-like structures composed of many cells.
  • Molecule= a combination of two or more atoms that are chemically bonded. A molecule is the smallest unit of a compound that can exist by itself and retain all of its chemical properties.
  • Molecule= Two or more atoms chemically united; the smallest particle of a compound that still possesses the characteristics of the compound.
  • Molybdenum= In mammography, the anode is made of this element.
  • Molybdenum-99=The parent element of technetium-99m.
  • Monitoring= determining the amount of ionizing radiation or radioactive contamination present. Also referred to as surveying.
  • Monoclonal immunoglobulin= Antibodies that are formed against a specific cell type.
  • Monocytes= Large mononuclear leukocytes.
  • Monteggia’s fracture= Isolated fracture of the shaft of the ulna associated with anterior dislocation of the radius at the elbow.
  • Moral agent= the one responsible for implementing an ethical decision.
  • Morgagni’s hernia= Protrusion of abdominal contents into the anterior and lateral aspects of the thoracic cavity.
  • Morphologic= Pertaining ‘to the form and structure of an organ.
  • Motherboard= largest circuitry board inside the computer; it contains many important small components to make the computer function properly.
  • Motile, motility= capable of spontaneous but unconscious or involuntary movement.
  • Motor= A device that is supplied with electrical
  • Movement= Second law of electrostatics that states only negative charges move along solid conductors.
  • Mucocutaneous= pertaining to the mucous membrane and the skin.
  • Mucosa, mucosal, mucous membrane= any one of four major kinds of thin sheets of tissue that cover or line various parts of the body. Mucous membrane lines cavities or canals of the body that open to the outside.
  • Multichannel Analyzer=A specialized scintillation detector that can select specific energy levels for detection.
  • Multifield Image Intensifier=A specialized image intensifier that allows for magnified fluoroscopic images.
  • Multilocular= Having many cells or compartments.
  • Multiple manual selection mode= area of interest is selected by the technologist, and the image is derived from the selected areas imaged in semiautomatic mode.
  • Multiple myeloma= A malignant tumor arising from plasma cells of bone marrow, causing a reduction in bone composition.
  • Multiple myeloma= Bone marrow malignancy.
  • Multiplex=A technique for putting two or more signals into a single channel.
  • Mural thrombosis= Thrombus originating in the vessel or cavity wall.
  • Mutation= an unusual change in genetic material occurring spontaneously or by induction.
  • Mutations= Alterations in the DNA structure that may become permanent hereditary changes.
  • Mutual Capacitance=Effective capacitance between two conductors when the effects of the other conductors and shield, if present, are removed.
  • Mutual induction= The result of two coils being placed in close proximity with a varying current supplied to the first coil, which then induces a similar flow in the second coil.
  • Mv=Millivolt (one=thousandth of a volt).
  • Mw=Milliwatt (one=thousandth of a watt).
  • Mycoplasma= Colloquial usage for any of a genus of tiny microorganisms, smaller than bacteria but larger than viruses, that appear to be the causative agents of many diseases.
  • Mycosis= Fungal infection.
  • Myelin sheath= Insulated by a fatty covering (as a nerve).
  • Myelocytic leukemia= Unregulated production of leukocytes.
  • Myelogram, myelography= an x-ray image/examination after the injection of a radiopaque medium into the subarachnoid space to demonstrate any distortions of the spinal cord, spinal nerve roots, and subarachnoid space.
  • Myelomeningocele= Herniation of the spinal cord and meninges through the skin.
  • Myocardial infarction (MI)= a heart attack; necrosis of heart muscle tissue caused by coronary artery thrombosis or occlusion.
  • Myocardial infarction (MI)= Infarction of the heart muscle.
  • Myxedema= Puffy thickening of the skin with slowing down of physical and mental activity caused by failure of the thyroid gland.
  • Narcotic= pertaining to a substance that produces insensibility or stupor.
  • Nasoenteric (NE) tube= tube placed through the nose and into the gastrointestinal tract as far as the small intestine to aspirate gas and fluid that may cause distention. Often used postoperatively on patients who have undergone abdominal surgery.
  • Nasogastric (NG) tube= a tube placed through the nose, pharynx, esophagus, and into the stomach to allow feeding of a patient directly into the stomach. May also be connected to a suction device to empty the stomach.
  • Natural magnet Created when iron oxide remains in the earth’s magnetic field for ages, slowly orienting the magnetic dipoles in the same direction (e.g., lodestones).
  • Navigation functions= options available on the workstation that allow movement through menus, menu options, image processing choices, as well as movement through a series or stack of images and/or patient image folders.
  • Nebulizer= a device for producing a fine spray. Intranasal and respiratory medications are often administered by a nebulizer. Also called atomizer.
  • Necrosis, necrotic= the death of living cells or tissues; containing or affected by dead cells or tissues.
  • Necrosis= Death of tissue.
  • Necrotic= Dead or decayed.
  • Negative contrast=Contrast medium that is radiolucent, such as effervescent granules that release carbon dioxide on contact with the fluid in the stomach.
  • Negatron= A negatively charged electron resulting from pair production.
  • Negligence= the commission of an act that a prudent person would not have done or the omission of a duty that a prudent person would have fulfilled, resulting in injury or harm to another person.
  • Neonate, neonatal= newborn; an infant from birth to 28 days of age; neonatal refers to the period immediately after birth.
  • Neoplasia= Any new and abnormal growth, especially when the growth is uncontrolled and progressive.
  • Neoplasm= Product of neoplasia.
  • Neoplastic= pertaining to the pathologic process resulting in the formation and growth of an abnormal mass of tissue.
  • Nephrocalcinosis= Calcium deposits within the substance of the kidney.
  • Nephrogram= a radiograph of the kidney; usually refers to an image of the parenchyma of the kidney in the early postinjection phase of an excretory urogram.
  • Network bridge= created so that larger networks can be segmented or broken up into smaller networks to reduce traffic within that network.
  • Network hub= central meeting point where cables from several devices can come together and share information throughout the group; it is a simple boxlike device with several wiring ports available to receive and pass on data to various pieces of equipment; the hub sends all information to every device connected.
  • Network interface card (NIC)=  interface between the computer and the network medium.
  • Network protocol= agreed-on set of rules for network communication.
  • Network router= device that can read portions of the messages and direct them to their intended target, even if the device is on a separate network and uses a different network protocol.
  • Network switch= similar to a hub but it sends data only to those devices to which the data are directed.
  • Network= two or more objects sharing resources and information; interconnected computers, terminals, and servers connected by communication channels sharing data and program resources.
  • Neurogenic= Originating in the nervous system neuron= Basic nerve cell.
  • Neurogenic= pertaining to the formation of nervous tissue; originating from the nervous system.
  • Neurologic= pertaining to the nervous system.
  • Neurology= the field of medicine that deals with the nervous system and its disorders.
  • Neurostimulator= an electronic device worn by patients to control pain and muscle spasm.
  • Neutron (n°)= Subatomic particle of an atom containing no charge.
  • Neutron= a small atomic particle possessing no electrical charge, typically found within an atom’s nucleus. Neutrons are, as the name implies, neutral in their charge. That is, they have neither a positive nor a negative charge. A neutron has about the same mass as a proton.
  • Neutrophils= Polymorphonuclear granular leukocyte.
  • Nidus= Focal point, especially of a stone or an inflammatory process.
  • Nit=A unit to measure luminance, equivalent to candela per square meter.
  • Noise=In a cable or circuit, any extraneous signal which tends to interfere with the signal normally present in or passing through the system.
  • Noise=Random signals or disturbances that interfere with proper image formation or demonstration.
  • Noncommunicating (obstructive) hydrocephalus= Obstruction of cerebrospinal fluid flow in the ventricular system causing enlarged ventricles.
  • Noninvasive= pertaining to a diagnostic or therapeutic technique that does not require the skin to be broken or a cavity or organ of the body to be entered.
  • Nonionic= pertaining to compounds that do not dissociate into charged particles when in solution.
  • Non-ionizing radiation= radiation that has lower energy levels and longer wavelengths than ionizing radiation. It is not strong enough to affect the structure of atoms it contacts but is strong enough to heat tissue and can cause harmful biological effects. Examples include radio waves, microwaves, visible light, and infrared from a heat lamp.
  • Nonmagnetic= Materials not affected by magnetic fields and cannot be magnetized (e.g., wood, glass, rubber, plastic).
  • Non-stochastic effect= an effect that can be related directly to the radiation dose received. The effect is more severe with a higher dose. It typically has a threshold, below which the effect will not occur. It is sometimes called deterministic effect. For example, a skin burn from radiation is a non-stochastic effect that worsens as the radiation dose increases.
  • Nonstochastic effects=Biologic response of radiation exposure that can be directly related to the dose received.
  • Nonstochastic= describes biologic radiation effects that are predictable and their intensity is dose-dependent. These effects occur only after a certain threshold amount of exposure has been received.
  • Normal saline= a 0.9% weight per volume (w/v) solution of sodium chloride in water that is isotonic with blood. It is available as a sterile solution for intravenous injection.
  • Normalization (automatic scaling)=Process whereby the computed radiography system automatically corrects for a manual setting and automatic exposure errors to produce consistently optimal images.
  • Normal-pressure hydrocephalus= Defective resorption of cerebrospinal fluid or an overproduction of cerebrospinal fluid causing ventricular enlargement.
  • Nosocomial infection= hospital-acquired disease.
  • Nosocomial= Incidences of infections being developed at the acute care facility.
  • Nosocomial= pertaining to a hospital.
  • NPO (nil per os, nothing by mouth)= a patient care instruction advising that the patient is prohibited from ingesting food, beverage, or medicine.
  • NPO=Nothing orally (by mouth).
  • Nu= Greek letter used to denote the number of cycles per second.
  • Nuclear energy= The energy stored in the bond of the nucleus of an atom.
  • Nuclear energy= the heat energy produced by the process of nuclear fission within a nuclear reactor or by radioactive decay.
  • Nuclear fuel cycle= the steps involved in supplying fuel for nuclear power plants. It can include mining, milling, isotopic enrichment, fabrication of fuel elements, use in reactors, chemical reprocessing to recover the fissile material remaining in the spent fuel, re-enrichment of the fuel material refabrication into new fuel elements, and waste disposal.
  • Nuclear magnetic moment= The rotating charge within a spinning nucleus which produces a magnetic field.
  • Nuclear medicine= the use of radionuclides to produce imaging studies that reveal information about physiology and function.
  • Nuclear medicine= Using radiopharmaceuticals to produce ionizing radiation, which is detected by a gamma camera to produce an image.
  • Nuclear reactor= A device in which a controlled, self-sustaining nuclear chain reaction can be maintained with the use of cooling to remove generated heat.
  • Nuclear Regulatory Commission (NRC)=Federal agency that enforces radiation safety guidelines.
  • Nuclear tracers= radioisotopes that give doctors the ability to “look” inside the body and observe soft tissues and organs, in a manner similar to the way x-rays provide images of bones. A radioactive tracer is chemically attached to a compound that will concentrate naturally in an organ or tissue so that an image can be taken.
  • Nucleon= a proton or aneutron; a constituent of the nucleus of an atom.
  • Nucleon= The protons and neutrons that make up the nucleus.
  • Nucleus= the central part of an atom that contains protons and neutrons. The nucleus is the heaviest part of the atom.
  • Nucleus= The small dense center of an atom; consists of protons and neutrons.
  • Nuclide= a general term applicable to all atomic forms of an element. Nuclides are characterized by the number of protons and neutrons in the nucleus, as well as by the amount of energy contained within the atom.
  • Nurse practitioner= a registered nurse who has received advanced education in nursing and clinical experience in a specialized area of nursing practice.
  • Nutritional deficiency= Lack of nutrients or their absorption.
  • Nyquist criterion= The sampling of the spatial resolution frequency signal twice from each cycle in digital systems.
  • Nyquist Frequency=The highest spatial frequency resolved by an imaging system, measured in line pairs per millimeter (lp/mm).
  • Nyquist theorem= when sampling a signal such as the conversion from an analog to a digital image, the sampling frequency must be greater than twice the bandwidth of the input signal so that the reconstruction of the original image will be nearly perfect.
  • Object–image receptor distance (OID)=Distance from the object being imaged to the IR.
  • Objective Plane=The region remaining relatively sharp in detail during tomographic procedures.
  • Oblique fracture= Runs a course of approximately 45 degrees to the long axis of the bone.
  • Oblique=Refers to rotation of a structure away from an AP or PA projection. When obliquity of the torso, vertebrae, or cranium is defined, the terms right or left and anterior or posterior are used with the term oblique to indicate which side of the patient is placed closer to the IR. In a right anterior oblique (RAO) position the patient is rotated so that the right anterior surface is placed closer to the IR. When obliquity of an extremity is defined, the term medial (internal) or lateral (external) is used with the term oblique to indicate which way the extremity is rotated from anatomic position and which side of the extremity is positioned closer to the IR. For a medial oblique position of the wrist, the medial side of the arm is placed closer to the IR.
  • Obturator internus fat plane=Fat plane that lies within the pelvic inlet next to the medial brim.
  • Occasionally exposed worker= Workers whose duties may occasionally bring them into areas where radiation exposure may occur.
  • Occlude, occlusion= (in anatomy) a blockage in a canal, vessel, or passage of the body.
  • Occlusal plane=Chewing surface of maxillary teeth.
  • Occupational Safety and Health Administration (OSHA)=Federal agency that oversees the workplace environment.
  • Occupationally exposed worker= Workers who have a significant potential for exposure to radiation in the course of their employment.
  • Octet rule= The number of electrons in the outermost shell never exceeds eight electrons.
  • Octreotide= Radioactive peptide tracer; a long-acting analog of the hormone somatostatin.
  • Off-focus radiation Photons that were not produced at the focal spot; also called extrafocal radiation.
  • Ohm= (SI) The unit of resistance.
  • Ohm=The unit of electrical resistance. The value of resistance through which a potential difference of one volt will maintain a current of one ampere.
  • Ohm’s Law=Stated E=IR, I=E/R or R=E/I. The current I in a circuit is directly proportional to the voltage E, and inversely proportional to the resistance R.
  • Oligemia= Decreased blood volume.
  • Oligodendrocytoma= Slow-growing glioma, usually arising in the cerebrum.
  • Oligohydramnios= Very small volume of amniotic fluid.
  • Oncology= the branch of medicine concerned with the study, diagnosis, and treatment of malignancy.
  • Oncology= The study of neoplasms.
  • Opacity= The ability of a film to stop light.
  • Opaque, opacify, opacification= pertaining to a substance or surface that neither transmits nor allows the passage of light. See also radiopaque.
  • Open equation= An equation that contains at least one unknown (variable).
  • Open fracture= Overlying skin is disrupted open reduction= Surgical procedure using direct or indirect manipulation of the fracture.
  • Open reduction= a surgical procedure for realigning a fracture or dislocation by exposing the skeletal parts involved.
  • Open-core transformer= Arrangement of two coils of wire each filled with an iron core in proximity to facilitate induction.
  • Operating system= software that controls the computer hardware and acts as a bridge between applications and the hardware.
  • Ophthalmology= the branch of medicine concerned with the study of the physiology, anatomy, and pathology of the eye and the diagnosis and treatment of disorders of the eye.
  • Opiate= a narcotic drug that contains opium; a derivative of opium.
  • Opioid= pertaining to natural and synthetic chemicals that have opium-like effects, although they are not derived from opium.
  • Opportunistic infection= an infection caused by normally nonpathogenic organisms in a host whose resistance has been decreased by disorders such as diabetes mellitus, human immunodeficiency virus (HIV) infection, or cancer, or by cancer treatment that causes immunosuppression.
  • Optical density numbers= The numbers displayed by a densitometer.
  • Optical disk=A large-capacity digital data storage device used to store digital images.
  • Optically stimulated luminescence (OSL) dosimeter= Measures radiation that passes through a thin strip of aluminum oxide. A laser light simulates the aluminum oxide, which becomes luminescent in proportion to the amount of radiation exposure.
  • Optimal kvp= The maximum kvp level that will produce images with appropriate contrast that
  • Optimum kvp=kvp that will provide adequate body part penetration and sufficient gray scale.
  • Oral= pertaining to the mouth. An oral temperature is taken with the thermometer probe in the mouth, under the tongue.
  • Orbital magnetic moment= The motion of a charged particle creates a magnetic force field perpendicular to the motion.
  • Orbitomeatal line=Imaginary line connecting the outer eye canthus and external acoustic opening.
  • Orthicon=A type of television camera tube.
  • Orthochromatic= A film that is not sensitive to the red spectrum.
  • Orthochromatic=A type of film that is sensitive mainly to light in the green portion of the visible light spectrum.
  • Orthopedic traction= a mechanical method that uses weights to provide a constant pull on part of the body for therapeutic reasons, such as to maintain alignment of fracture fragments or to relieve pressure caused by spinal injury.
  • Orthopedic= pertaining to the locomotor system of the body, including the skeleton, muscles, and joints.
  • Orthopnea= an abnormal condition in which a person must sit or stand to breathe deeply or comfortably.
  • Orthostatic hypotension= a transient state of cerebral anoxia and low blood pressure occurring when an individual assumes a standing posture. Same as postural hypotension.
  • Osmolality= the concentration of particles in a solution, which determines the osmotic pressure of the solution expressed in osmoles or milliosmoles per kilogram of water. Osmotic pressure influences the passage of water through semipermeable membranes. Normal adult blood osmolality is 285 to 295 mosm/kg H2O.
  • Osseous= consisting of or resembling bone; bony.
  • Ossification= Bone formation.
  • Osteitis deformans= New bone growth resulting from an increase in bone cell activity
  • Osteoblastic metastases= New bone growth resulting from the spread of cancer in bone.
  • Osteoblastic= Forming bony tissue.
  • Osteochondroma= A tumor in the bone and cartilage.
  • Osteoclastic= Bone resorption.
  • Osteogenic sarcoma= Malignant tumor composed of osteoblasts that produce osteoids and spicules of calcified bone.
  • · Osteolytic metastases= Destruction of bone due to malignancies that have spread to the bone.
  • Osteolytic= Destroying bone.
  • Osteomalacia= A defect in bone mineralization, causing decreased composition.
  • Osteomalacia= Insufficient mineralization of the adult skeleton.
  • Osteomas= Tumor composed of bone tissue.
  • Osteoporosis= A defect in bone production due to failure of osteoblasts to lay down bone matrix.
  • OTC= abbreviation for over the counter, a drug available to the consumer without a prescription.
  • Outpatient= a patient, not hospitalized, who is being treated in an office, clinic, or other ambulatory care facility; a patient seen briefly in a hospital department without being admitted for an overnight stay.
  • Output=The useful power or signal delivered by a circuit or device.
  • Overhead suspension system= A type of radiography unit that allows control of longitudinal and transverse positioning as well as vertical distance.
  • Ovulation= Release of the ovum from the ovary.
  • Oxidation/Reduction Reaction=A chemical change in which electrons are removed (oxidation) from an atom, ion, or molecule, accompanied by a simultaneous transfer of electrons to another atom, ion, or molecule (reduction). Also known as redux.
  • Ozone=Extremely reactive form of oxygen, normally occurring around electrical discharges and present in the atmosphere in small but active quantities. In sufficient concentrations is can break down certain rubber insulations under tension (such as a bent cable).
  • P-100 Filter= P-100 filtering face piece disposable particulate respirators are capable of filtering at least 99.97% of airborne particles measuring ≥0.3 micron in diameter. Filtering face piece respirators designated with a “P” are strongly resistant to oil.
  • Pacemaker= an electric device used in most cases to increase the heart rate in severe bradycardia by electrically stimulating the heart muscle.
  • Pacemaker=Used to regulate the heart rate by supplying electrical stimulation to the heart. This electrical signal will stimulate the heart the amount needed to maintain an effective rate and rhythm.
  • PACS administrator= the person trained to oversee the PACS.
  • PACS= abbreviation for picture archiving and communication system, the software and hardware that supports digital imaging systems and networks.
  • PACS= picture archival and communication system; consists of digital acquisition, display workstations, and storage devices interconnected through a network.
  • PACU= abbreviation for postanesthesia care unit, an area designed and staffed to provide close observation and care of patients following operative procedures requiring an anesthetic agent. Also called a recovery room.
  • Paget’s disease= New bone growth resulting from an increase in bone cell activity.
  • Pair production= An interaction between x-rays and matter characterized by the conversion of the energy of an x-ray photon into matter in the form of two electrons.
  • Palliative= a substance or treatment that soothes or relieves.
  • Pallor= an unnatural paleness or absence of color in the skin.
  • Palmar=Anterior surface of the hand.
  • Palpate=Act of touching or feeling a structure through the skin.
  • Palpitations= Rapid or fluttering beating of the heart, of which one is aware.
  • Panchromatic= A film that is sensitive to all colors.
  • Panchromatic=A type of film that is sensitive to all wavelengths of the visible light spectrum.
  • Panoramic dental and facial unit= Specialized radiography equipment for combined tomography of facial and dental structures.
  • Pantomography= A type of tomography that permits a slit scan of curved surfaces such as the face and head.
  • Papillary carcinoma= Slow-growing cystic thyroid carcinoma.
  • Paradoxical= Seeming to contradict the known facts.
  • Parallel circuit= An electric circuit designed to send electrons through various resistance devices by giving each component its own branch.
  • Parallel Circuit=A circuit in which the identical voltage is presented to all components, with current dividing among the components according to the resistances or the impedances of the components.
  • Parallel grid= A grid created with the lead and interspace strips running parallel to one another; the lines will never intersect.
  • Paralysis= the loss of muscle function, loss of sensation, or both.
  • Paramagnetic agents= agents with a small but positive magnetic susceptibility, the small addition of which may greatly reduce the MRI relaxation times of a substance and used as a contrast medium in MRI.
  • Paramagnetic= Materials that have a low permeability and weak attraction to magnetic fields (e.g., aluminum).
  • Parathormone (PTH)= Secreted by the parathyroids; Regulates the blood levels of calcium and phosphate.
  • Parenchyma= Essential tissue of an organ.
  • Parenteral= pertaining to treatment introduced into the body other than through the digestive system.
  • Pareto chart=A causal analysis tool that is a variation of a histogram.
  • Parietal= pertaining to the wall of a cavity (for example, the parietal pleura lines the interior walls of the thoracic cavity).
  • Particulate radiation= High-energy electrons, neutrons, and protons that produce ionization in matter by direct atomic collisions.
  • Pass box= A lightproof container set in the wall of the darkroom used to pass film through for processing.
  • Passive immunity= short-term resistance to infection produced by preformed antibodies. Preformed antibodies may be injected in the form of pooled immune globulin from the general population; they are passed to infants in utero or in breast milk.
  • Patent ductus arteriosus= Abnormal connection between the pulmonary artery and aorta caused by lack of the fetal ductus arteriosus.
  • Patent, patency= a state of being open or exposed.
  • Pathogen= any microorganism capable of producing disease.
  • Pathognomonic= Especially distinctive or characteristic of a disease or pathologic condition.
  • Pathologic fracture= Occurs when the bone weakens as a result of another process, such as a tumor, infection, or metabolic disease.
  • Pathology The medical science concerned with all aspects of disease, including the structural and functional changes caused by a disease process.
  • Pathways= the routes by which people are exposed to radiation or other contaminants. The three basic pathways are inhalation, ingestion, and direct external exposure.
  • Patient demographics= input information regarding patient age, identifying number, ordering physician, and so on.
  • Patient equivalent phantom= A dummy or surrogate device that can be imaged that will mimic the thickness of an actual patient; used to control quality and acceptance levels of radiographic images.
  • Peak=The maximum instantaneous value of a varying current or voltage.
  • Pectus excavatum= Funnel chest; depressed sternum.
  • Pedal pulse= a count of the heart rate by means of the advancing pressure wave in the dorsalis pedis artery on the dorsal aspect (instep) of the foot.
  • Pediatric= pertaining to health care and treatment of children and the study of childhood diseases.
  • Pedunculated= Having a stalk (pedicle).
  • Peer-to-peer network= each computer on the network is considered equal; no computer has ultimate control over another.
  • Pelken spur= Marginal spur formation.
  • Pelvic kidney= Kidney located in the pelvis.
  • Penetrability= The ability of the x-ray to pass through structures and tissues.
  • Penetrating radiation= radiation that can penetrate the skin and reach internal organs and tissues. Photons (gamma rays and x-rays), neutrons, and protons are penetrating radiations. However, alpha particles and all but extremely high-energy beta particles are not considered penetrating radiation.
  • Penetration=Ability of x-ray photons to exit the patient’s body.
  • Penetrometer A series of increasingly thick, uniform absorbers.
  • Penicillin= any one of a group of antibiotics derived from cultures of species of the fungus Penicillium or produced semisynthetically.
  • Penumbra= A geometric unsharpness around the periphery of the image.
  • Percutaneous= performed through the skin, such as a biopsy performed using a needle.
  • Perforated ulcer= an ulcer (sore) that penetrates the thickness of a wall or membrane.
  • Pericapsular fat plane=Fat plane.
  • Pericardium= a fibroserous sac that surrounds the heart and the roots of the great vessels.
  • Pericardium= Membrane surrounding the heart.
  • Period= The time required to complete one cycle of the wave.
  • Periodicity=The uniformly spaced cable impedance variations that result in addition of the reflections of a signal. The distance between them is the half wavelength most affected. Multiples of that frequency are also affected. Even very slight variations, which appear over and over in a construction or installation, can have major effects on signal integrity because of periodicity.
  • Periosteum= Fibrous membrane covering the outer surface.
  • Peripheral nervous system (PNS)= Nerves outside the central nervous system; motor and sensory nerves.
  • Peripheral= Outside or away from the central portion of a structure.
  • Peristalsis= the coordinated, rhythmic, serial contraction of smooth muscle that forces food through the digestive tract, bile through the bile duct, and urine through the ureters.
  • Peristalsis= Wormlike movement by which the alimentary canal or other tubular organ propels its contents.
  • Peritonitis= inflammation of the membrane lining the abdominal cavity (peritoneum). It is produced by bacteria or irritating substances introduced into the abdominal cavity by a penetrating wound or perforation of an organ in the gastrointestinal tract or the reproductive tract.
  • Permanent magnet = a magnet that has a high coercivity, meaning that it retains magnetism for a long time.
  • Permeability The ease with which a material can be magnetized.
  • Permeability= the degree to which one substance allows another substance to pass through it.
  • Permeable= Membrane allowing fluids to pass through.
  • Permeative= Diffusely spreading through or penetrating a substance, tissue, or organ, as by a disease process, such as cancer.
  • Pernicious anemia= Progressive megaloblastic anemia that results from lack of intrinsic factor that is required for absorption of vitamin B12.
  • Personal protective equiptment= Clothing and/or equipment worn by workers (including first responders and first receivers) to prevent or mitigate job-related illness or injury. Individual PPE elements can include respiratory and percutanous protective equipment.
  • Personnel monitoring device= Instrument worn by health care workers who work regularly in radiation-exposed environments.
  • Pertussis= an acute, highly contagious respiratory disease characterized by paroxysmal coughing that ends in a loud whooping inspiration. Also called whooping cough.
  • Petit mal seizure= Characterized by sudden, momentary loss of consciousness.
  • Phagocytosis= the process by which certain cells engulf and destroy microorganisms and cellular debris.
  • Phantom image=Artifact that occurs in computed radiography when the imaging plate is not erased adequately before the next image is exposed on it and two images are recorded onto the plate phosphor.
  • Phantom=A quality control test tool used to simulate human tissue or body parts or demonstrate certain image characteristics.
  • Pharmacodynamics= the study of how a drug acts on a living organism, including the pharmacological response and the duration and magnitude of response observed.
  • Pharmacokinetics= the study of how drugs enter the body, are absorbed, reach their site of action, are metabolized, and exit the body.
  • Pharmacology= the study of the preparation, properties, uses, and actions of drugs.
  • Pharyngitis= inflammation or infection of the throat.
  • Phase Shift=A change in the phase relationship between two alternating quantities.
  • Phase=An angular relationship between waves.
  • Phenidone= A chemical that quickly reduces silver, enhancing fine detail and subtle shades of gray, and works only in areas of light exposure.
  • Phlebitis= inflammation of a vein.
  • Phlebotomist= a person with special training in the practice of drawing blood.
  • Phosphor center= see color layer.
  • Phosphor layer= A layer of material used in an intensifying screen that is capable of absorbing the energy of an incident x-ray photon and then emitting light photons.
  • Phosphor layer= layer of photostimulable phosphor that “traps” electrons during exposure; usually made of phosphors from the barium fluorohalide family (e.g., barium fluorohalide, chlorohalide, or bromohalide crystals).
  • Phosphorescence= The ability of a material to delay emission of light in response to excitation.
  • Phosphorescence=Delayed emission of light—often called afterglow or lag—not desired for use in intensifying screens that occurs when certain crystals emit light sometime after 10−8 seconds after exposure to radiation.
  • Phosphors= fluorescent crystals that give off light when exposed to x-rays. See also fluorescence.
  • Photodetector=An electronic device used for detecting photons of light, x-rays, or gamma rays.
  • Photodisintegration= An interaction between x-rays and matter characterized by the interaction between a high-energy photon and the nucleus. The high-energy photon strikes the nucleus; the nucleus absorbs all the photons energy and then emits a nuclear fragment.
  • Photoelectric absorption= An interaction between x-rays and matter characterized by an incident electron with slightly greater energy than the binding energy of the electrons in the inner shells, ejecting an electron from the inner shell while being absorbed in the reaction, resulting in an ionized atom.
  • Photoelectron= An ionized atom with a missing inner-shell electron resulting from ejection of the electron due to photoelectric absorption.
  • Photoemission=The emission of electrons from a material after exposure to light or other ionizing radiation.
  • Photofluorospot=A method of recording static images during fluoroscopy.
  • Photometer= device used to measure the luminescence of areas on the monitor.
  • Photometry=The study and measurement of light.
  • Photomultiplier Tube (PMT)=A device used in many radiation detection applications that converts low levels of light into electronic pulses.
  • Photomultiplier tube= a device used in many radiation detection applications that converts low levels of light into electrical pulses.
  • Photomultiplier= electronic device that amplifies light energy.
  • Photon= a discrete “packet” of pure electromagnetic energy. Photons have no mass and travel at the speed of light. The term “photon” was developed to describe energy when it acts like a particle (causing interactions at the molecular or atomic level), rather than a wave. Gamma rays and x-rays are photons.
  • Photon= A small bundle of energy. The specific amount of energy depends on frequency; also known as a quantum.
  • Photon= the smallest quantity of electromagnetic energy. It has no mass and no charge and travels at the speed of light. Photons may occur in the form of light rays, x-rays, gamma rays, and other electromagnetic energies.
  • Photon=The smallest quantity of electromagnetic energy.
  • Photopeak=The peak amplitude on an oscilloscope display.
  • Photosensitive= reactive to light.
  • Photostimulable luminescence (PSL)=  light produced by a phosphor when struck by light or x-ray photons.
  • Photostimulable phosphor= phosphor that produces light when stimulated by light or x-ray photons.
  • Photostimulable Phosphor=A barium fluorohalide material used to capture radiographic images in computerized radiography (CR) systems.
  • Phototimer= Often used to describe all automatic exposure controls; this type of AED is rarely used in modern radiography.
  • Pia mater= Innermost meningeal covering.
  • Pickup=Any device which is capable of transforming a measurable quantity of intelligence (such as sound) into relative electrical signals (e.g., a microphone).
  • Picofarad=One trillionth of a farad. A micromicrofarad. Abbreviated pf in modern usage or mmf in earlier usage.
  • Picture archival and communication system= networked group of computers, servers, and archives that can be used to manage digital images.
  • Picture archiving and communication system (PACS)= A computer system that can manage images in an electronic form.
  • Picture Archiving and Communication System (PACS)=A computerized system that stores patient images to allow access from remote locations.
  • Pincushion Distortion=A type of distortion in image-intensified images caused by the projection of a curved image onto a flat surface.
  • Pinna= Cartilaginous portion of the external ear.
  • Pitch= The extension or contraction of the helix; the ratio of the distance the table moves during one 360-degree tube rotation to the total beam collimation.
  • Pitchblende= a brown to black mineral that has a distinctive luster. It consists mainly of uraninite (UO2), but also contains radium (Ra). It is the main source of uranium (U) ore.
  • Pituitary adenomas= Tumor composed of glandular tissue of the pituitary gland.
  • Pixel Size=The size of the picture element found in the matrix of a computer-generated image; the smaller the pixel size, the greater the spatial resolution.
  • Pixel= basic picture element on a display.
  • Pixel= Picture elements; individual matrix boxes.
  • Pixel=Abbreviation for picture elements. Small cells of information that make up the digital image on a computer monitor screen.
  • Pixel=Single cell within a matrix.
  • Plaintiff= a person who files a civil lawsuit initiating a legal action.
  • Plantar flexion=Act of moving the toes and forefoot downward.
  • Plantar=Pertaining to the sole of the foot.
  • Plantar-flex=Act of moving the toes and forefoot downward (pointing the toes).
  • Platelets= Smallest blood cell; contains hemoglobin.
  • Pleura, pleural= a delicate serous membrane covering the lung and lining the thoracic cavity.
  • Pleural drainage tube=Thick-walled tube used to remove fluid or air from the pleural space that could result in collapse of the lung.
  • Pleural effusion= an abnormal accumulation of fluid within the thoracic cavity between the visceral and parietal pleura.
  • Pleural effusion=Fluid in the pleural cavity.
  • Pleural effusions= The filling of the pleural cavity with blood or serous fluid.
  • Pleurisy= inflammation of the pleura, sometimes resulting in adhesion of pleural membranes and causing dyspnea.
  • Plumbicon=A type of television camera tube.
  • Plume= the material spreading from a particular source and traveling through environmental media, such as air or ground water. For example, a plume could describe the dispersal of particles, gases, vapors, and aerosols in the atmosphere, or the movement of contamination through an aquifer (for example, dilution, mixing, or adsorption onto soil).
  • Pluridirectional Tomography=A specialized type of tomographic unit that allows for multiple-direction motion of the x-ray source and image receptor.
  • Plutonium (Pu)= a heavy, man-made, radioactive metallic element. The most important isotope is Pu-239, which has a half-life of 24,000 years. Pu-239 can be used in reactor fuel and is the primary isotope in weapons. One kilogram is equivalent to about 22 million kilowatt-hours of heat energy. The complete detonation of a kilogram of plutonium produces an explosion equal to about 20,000 tons of chemical explosive. All isotopes of plutonium are readily absorbed by the bones and can be lethal, depending on the dose and exposure time.
  • Pneumatic= pertaining to air or gas.
  • Pneumectomy=Removal of a lung.
  • Pneumococcus= Genus of gram-positive bacteria.
  • Pneumoconiosis= The inhalation of dust particles, causing fibrotic scarring of the lungs.
  • Pneumonectomy= The removal of a lung.
  • Pneumonia= Inflammation of lung tissues, causing fluid to fill the alveolar spaces.
  • Pneumonia=an acute inflammation of the lungs, often caused by inhaled pneumococci of the species Streptococcus pneumoniae.
  • Pneumonitis= Inflammation of lung tissues, causing fluid to fill the alveolar spaces.
  • Pneumoperitoneum= Presence of free gas in the peritoneal cavity.
  • Pneumothorax= a collection of air or gas in the pleural space causing the lung to collapse.
  • Pneumothorax= Free air in the pleural cavity that displaces lung tissue.
  • Pneumothorax=Presence of air in the pleural cavity.
  • Pocket dosimeter= a personal use ionization chamber. When exposed to radiation, ionization occurs in the chamber, which neutralizes a positively charged electrode that will appear as movement of an exposure scale.
  • Point spread function (PSF)= Expression of the boundaries of an image; determined by a mathematical measurement of an image produced at a single point.
  • Point Spread Function=A graphic demonstration of image resolution.
  • Polar reversal = event during which earth’s magnetic fields switch, probably due to the volatile nature of the liquid outer core that generates earth’s electromagnetism.
  • Polonium (Po)= a radioactive chemical element and a product of radium (Ra) decay. Polonium is found in uranium (U) ores.
  • Polyhydramnios= Excessive accumulation of amniotic fluid.
  • Polypoid= Resembling a polyp.
  • Pons= Part of the brain stem containing centers for some reflexes.
  • Population=Any group measured for some variable characteristic from which samples may be taken for statistical purposes.
  • Port= collection of connectors sticking out of the back of the computer that link adapter cards, drives, printers, scanners, keyboards and mice, and other peripherals that may be used.
  • Portable X-Ray Generator=A type of x-ray generator that is small enough to be carried from place to place by one person.
  • Positive beam limitation device (PBL)= An automatic collimator that adjusts to the size and placement of the cassette.
  • Positive contrast=Contrast medium that is radiopaque, such as barium.
  • Positron emission tomography (PET)= a computerized nuclear medicine scanning modality involving the injection of radionuclides that emit ion pairs.
  • Positron emission tomography (PET)= Imaging technique using a radiopharmaceutical that emits a positron and is detected by a moving gamma camera.
  • Positron Emission Tomography (PET)=An imaging technique whereby a positron-emitting radionuclide is administered to a patient, and the result is the release of photons by an annihilation reaction.
  • Positron= A positively charged electron resulting from pair production.
  • Posterior (postero-)Refers to the back of the patient; used to express something that is situated at or directed toward the back and includes the backs of the hands and bottoms of the feet, as in anatomic position. The knee joint is posterior to the patella.
  • Posterior shoulder dislocation=Shoulder condition in which the humeral head is demonstrated posteriorly, beneath the acromion process.
  • Postictal= descriptive of the immediate period following a seizure.
  • Postmenstrual phase= Follows the menstruation phase in the menstrual cycle.
  • Postpartum= After childbirth.
  • Postprocessing=A manipulation of the image data in the memory of the computer, before the image is displayed on a monitor.
  • Post-Transfusion Graft-vs.-Host Disease= PT-GVHD occurs when donor lymphocytes in transfused blood attack recipient organs and tissues recognizing recipient HLA and are not eliminated by host immunological defense.
  • Postural hypotension= a transient cerebral anoxia that occurs when a patient is bedridden for an extended period of time and blood pools in the extremities when the torso is elevated. Same as orthostatic hypotension.
  • Potent, potency= active, powerful, or strong.
  • Potential difference= The force or strength of electron flow; also known as electromotive force (emf).
  • Potential energy= The energy an object has because of its position.
  • Potentiometer= A variable resistor that permits a variable contact to slide along a series circuit of resistance coils.
  • Potting=Sealing by filling with a substance to exclude moisture.
  • Pott’s disease= Tuberculosis of the spine.
  • Power loss formula= Calculation that can provide an understanding of the changes in resistance to heat output.
  • Power Loss=The difference between the total power delivered to a circuit, cable, or device and the power delivered by that device to a load.
  • Power Ratio=The ratio of power appearing at the load to the input power.
  • Power supply= delivers all electricity and provides connections to power devices in the computer.
  • Power=The amount of work per unit of time. Usually expressed in watts.
  • Precession= Rotation of the axis of rotation within a nucleus when it encounters a magnetic field; causes a loss in momentum.
  • Precipitate= to cause a substance to separate or to settle out of solution; a substance that has separated from or settled out of a solution.
  • Precipitation=A process whereby silver particles are made to settle out of a used fixer solution.
  • Premedication= any sedative, tranquilizer, hypnotic, or anticholinergic medication administered before anesthesia or other procedure.
  • Prenatal radiation exposure= radiation exposure to an embryo or fetus while it is still in its mother’s womb. At certain stages of the pregnancy, the fetus is particularly sensitive to radiation and the health consequences could be severe above 5 rads, especially to brain function.
  • Preservative= A chemical used in film processing to help decrease the oxidation of the reducing agents when they are combined with air; also used in fixer solution to aid in removal of silver from the emulsion.
  • Preventative maintenance (PM)= periodic testing of equipment and materials before problem occurrence.
  • Prevertebral fat stripe=Fat stripe located anterior to the cervical vertebrae.
  • Primary barrier= A shielding structure that can be struck by the primary x-ray beam exiting the x-ray tube.
  • Primary coil=The coil first supplied with the current.
  • Primary health care= a basic level of health care that includes programs directed at the promotion of health, early diagnosis of disease or disability, and prevention of disease.
  • Primary stage= Initial phase of a disease process.
  • Primary x-ray beam= that portion of the x-ray beam between the x-ray tube and the patient; it is unattenuated except by air.
  • Prime factor= Factors related to x-ray emission that are under the direct control of the radiographer; milliamperage, kilovoltage, and distance.
  • Principle-based ethics, principlism= a widely accepted standard for selecting and defending solutions to ethical dilemmas in health care communities based upon six moral principles.
  • Process=An ordered series of steps that help achieve a desired outcome.
  • Profile=Outline of an anatomic structure: The glenoid fossa is demonstrated in profile on a Grashey method image.
  • Progesterone= Hormone secreted by the corpus luteum to help regulate menstrual cycle and fertilization.
  • Prognosis= a prediction of the probable outcome of a disease based on the condition of the person and the usual course of the disease as observed in similar situations.
  • Program= Operating instructions.
  • Progressive scanning= Increases resolution by scanning all 52 5 lines in order.
  • Project=The act of throwing the image of an anatomic structure forward. An angled central ray projects the anatomic part situated farther away from the IR farther than the anatomic part situated closer to the IR.
  • Projection=Term used to describe the entrance and exit points of the x-ray beam as it passes through the body when an image is taken. In a projection, the path from the first location to the second must be a straight line. These include anteroposterior, inferosuperior, lateromedial, mediolateral, posteroanterior, and superoinferior projections.
  • Proliferate= To multiply rapidly, increase profusely.
  • Pronate=To rotate or turn the upper extremity medially until the hand’s palmar surface is facing downward or posteriorly.
  • Pronator fat stripe=Soft tissue structure demonstrated on lateral wrist images located parallel to the anterior surface of the distal radius.
  • Propagation Delay=Time required for a signal to pass from the input to the output of a device.
  • Proprietary medication= medicinal substance that is protected from commercial competition because its ingredients or methods of manufacture are kept secret or are protected by trademark or patent.
  • Prostate gland= Produces fluid that makes up the semen.
  • Prosthesis (plural, prostheses)= an artificial replacement for a missing body part, or a device designed and applied to improve function, such as a hearing aid.
  • Protective Action Guide (PAG)= projected dose to the public from an unplanned release of radioactive material at which a specific Protective Action is recommended to reduce or avoid that dose.
  • Protective Actions= During a radiation incident, actions recommended by incident managers (e.g., shelter-in-place, evacuation, interdiction of food, etc.) Intended to protect the public from future radiation exposure.
  • Protective coat= A layer of material used in an intensifying screen applied to the top of the phosphor layer to protect it from abrasions and stains; usually thick plastic.
  • Protective device= Items worn by the radiation worker to reduce exposure to radiation.
  • Protective housing= The entire cathode and anode assembly is housed within this metal structure.
  • Protective layer= very thin, tough, clear plastic covering in the imaging plate for protection of the phosphor layer.
  • Protocol= a written plan specifying the procedures to be followed in giving a particular examination, in conducting research, or in providing care for a particular condition.
  • Proton (p+)= Positively charged subatomic particle of an atom.
  • Proton (spin) density= The quantity of resonating spins in a tissue.
  • Proton spin density image= The effect that is measured by the number of protons spinning in tissue volume.
  • Proton= a small atomic particle, typically found within an atom’s nucleus, that possesses a positive electrical charge. Even though protons and neutrons are about 2,000 times heavier than electrons, they are tiny. The number of protons is unique for each chemical element.
  • Protozoan (plural, protozoa)= single-celled microorganism of the subkingdom Protozoa.
  • Protract=To move a structure forward or anteriorly: The shoulder is protracted when it is drawn forward.
  • Proximal (proximo-)=Refers to a structure that is closest to the source or beginning. The shoulder joint is proximal to the elbow joint. Or, The hepatic flexure is proximal to the splenic flexure.
  • Proximal convoluted tubule= Second part of the nephron, first part of the renal tubule.
  • Proximal= nearer to a point of reference or attachment, usually the trunk of the body, than other parts of the body or of the same structure. For example, the elbow is proximal to the wrist.
  • Psoriatic arthritis= Rheumatoid-like destructive process involving the peripheral joints in patients with psoriasis.
  • Psychomotor= pertaining to or causing voluntary movements usually associated with neural activity. Psychomotor skill is the ability to move purposefully.
  • Psychrometer=An instrument used to measure relative humidity.
  • Pulmonary arterial catheter (CVC)=Catheter used to measure atrial pressures, pulmonary artery pressure, and cardiac output.
  • Pulmonary edema= the accumulation of extravascular fluid in lung tissues and alveoli, caused most commonly by congestive heart failure.
  • Pulmonary edema= The filling of the interstitial lung tissues and alveoli with fluid.
  • Pulmonary mycosis= Fungal infection of the lung.
  • Pulmonary valve= Three semilunar cusps between the right ventricle and the pulmonary trunk.
  • Pulmonary= pertaining to the lungs or the respiratory system.
  • Pulse Height Analyzer (PHA)=A device that accepts or rejects electronic pulses according to their amplitude or energy.
  • Pulse oximeter= a digital monitor of pulse rate and oxygen saturation of the blood that is connected to the patient by means of a cable and a small probe attached to a finger or earlobe.
  • Pulse=A current or voltage which changes abruptly from one value to another and back to the original value in a finite length of time. Used to describe one particular variation in a series of wave motions.
  • Punctate= Marked with dots or tiny spots.
  • Purpura= Spontaneous hemorrhages in the skin or mucous membrane.
  • Pyloric stenosis= a narrowing of the pyloric sphincter at the outlet of the stomach, causing an obstruction that blocks the flow of food into the small intestine.
  • Pylorospasm= an involuntary contraction of the muscle that forms the pyloric sphincter at the outlet of the stomach, as occurs in pyloric stenosis.
  • Pyogenic= Bacteria that lead to the production of a thick, yellow fluid called pus.
  • Pyosalpinx= Fallopian tube filled with pus.
  • Pyramid problem= Acceptable images depend on many factors. If any of those factors are off, it can cause a problem in various other factors, thus a pyramid affect of problems is the result.
  • Pyrexia= the abnormal elevation of body temperature above 37° Celsius (98.6° Fahrenheit). Same as fever.
  • QAM=Quandrature Amplitude Modulation.
  • QPSK=Quaternary Phase Shift Keying or Quadrature PSK.
  • Qualitative= pertaining to the quality, value, or nature of something.
  • Quality assurance= All activities that provide adequate confidence that a radiology service will render consistently high-quality images and services.
  • Quality assurance= another term for quality management, which is now considered antiquated; typically focuses on the person rather than the process.
  • Quality Assurance=An all-encompassing management program used to ensure excellence.
  • Quality control (QC) station= dedicated computer and monitor for the purpose of reviewing digital images.
  • Quality control (QC)=  subdivision of quality management that focuses on equipment functions.
  • Quality control= The aspect of quality assurance that monitors technical equipment to maintain superior standards.
  • Quality Control=The part of the quality assurance program that deals with techniques used in monitoring and maintenance of technical systems.
  • Quality factor (Q)= The factor by which the absorbed dose (rad or gray) must be multiplied to obtain a quantity that expresses, on a common scale for all ionizing radiation, the biological damage (rem or sievert) to the exposed tissue. It is used because some types of radiation, such as alpha particles, are more biologically damaging to live tissue than other types of radiation when the absorbed dose from both is equal. The term, quality factor, has now been replaced by “radiation weighting factor” in the latest system of recommendations for radiation protection.
  • Quality factor= Radiation weighting factor, specific to specific types of radiation; accounts for the biological effectiveness of the specific radiation.
  • Quality Improvement Team=A group of individuals who are responsible for implementing the solutions that were derived by a focus group.
  • Quantitative= capable of being measured.
  • Quantization=Process of converting an analog image into digital (binary) data for processing by a computer.
  • Quantum (plural, quanta)= a group or “bundle” of photons.
  • Quantum mottle= A lack of sufficient incoming data to process an image; also known as quantum noise.
  • Quantum mottle= failure of an imaging system to record densities usually caused by a lack of x-ray photons.
  • Quantum Mottle=Image noise caused by statistical fluctuations in the number of photons creating the image.
  • Quantum mottle=Mottled or grainy appearance of an image when insufficient milliampere-seconds (mas) have been used.
  • Quantum noise (mottle)=Graininess or random pattern that is superimposed on the image, obscuring information. It is present when photon flux is insufficient.
  • Quantum noise= A lack of sufficient incoming data to process an image; also known as quantum mottle.
  • Quantum noise= recording error in the digital image.
  • Quantum= A small bundle of energy. The specific amount of energy depends on frequency; also known as a photon.
  • Quark= Subnuclear structure that makes up protons and neutrons.
  • Quenching= Overheating of the superconducting magnet due to vaporization of gasses needed to maintain the environment for superconduction.
  • R=F=Radio=frequency.
  • Rad (radiation absorbed dose)= a basic unit of absorbed radiation dose. It is a measure of the amount of energy absorbed by the body. The rad is the traditional unit of absorbed dose. It is being replaced by the unit gray (Gy), which is equivalent to 100 rad. One rad equals the dose delivered to an object of 100 ergs of energy per gram of material.
  • Rad= abbreviation for radiation absorbed dose, the basic unit of absorbed dose of ionizing radiation in the British system of radiation measurement. One rad is equal to the absorption of 100 ergs of radiation energy per gram of matter.
  • Rad= Term used to describe the measurement related to the absorbed dose of radiation; unit of absorberrenergy or dose applicable to any material; 100 ergs of energy absorbed in 1 gram of absorbing material.
  • Radial deviation=While maintaining PA projection, the distal hand is moved toward the radial side as much as the wrist will allow.
  • Radiation field= the cross section of the x-ray beam at the point where it is utilized.
  • Radiation fog= The result of scattered photons striking the radiographic film and placing a density on the film that is unrelated to the patient’s anatomy.
  • Radiation protection= sometimes known as radiological protection, is the science of protecting people and the environment from the harmful effects of ionizing radiation, which includes both particle radiation and high energy electromagnetic radiation. (source= Wikipedia)
  • Radiation warning symbol= a symbol prescribed by the Code of Federal Regulations. It is a magenta or black trefoil on a yellow background. It must be displayed where certain quantities of radioactive materials are present or where certain doses of radiation could be received.
  • Radiation worker= An individual, who through occupational risk, has a certain likelihood of exposure to ionizing radiation in the course of his or her normal duties.
  • Radiation= Energy emitted and transferred through matter.
  • Radiation= energy moving in the form of particles or waves. Familiar radiations are heat, light, radio waves, and microwaves. Ionizing radiation is a very high-energy form of electromagnetic radiation.
  • Radio Frequency (RF)=Radio Frequency. Includes frequencies from a few kilohertz to several hundred gigahertz. Used to transmit information from point to point over the airwaves or down coaxial cable.
  • Radioactive contamination= the deposition of unwanted radioactive material on the surfaces of structures, areas, objects, or people. It can be airborne, external, or internal.
  • Radioactive decay= the spontaneous disintegration of the nucleus of an atom.
  • Radioactive half-life= the time required for a quantity of a radioisotope to decay by half. For example, because the half-life of iodine-131 (I-131) is 8 days, a sample of I-131 that has 10 mci of activity on January 1, will have 5 mci of activity 8 days later, on January 9.
  • Radioactive material= material that contains unstable (radioactive) atoms that give off radiation as they decay.
  • Radioactive waste= Disposable, radioactive materials resulting from nuclear operations. Wastes are generally classified into two categories, high-level and low-level waste.
  • Radioactivity= the process of spontaneous transformation of the nucleus, generally with the emission of alpha or beta particles often accompanied by gamma rays. This process is referred to as decay or disintegration of an atom.
  • Radioassay= a test to determine the amounts of radioactive materials through the detection of ionizing radiation. Radioassays will detect transuranic nuclides, uranium, fission and activation products, naturally occurring radioactive material, and medical isotopes.
  • Radiofrequency pulse (RF)= Refers to that portion of the electromagnetic spectrum in which electromagnetic waves can be generated by alternating current—commonly in the 1- to 100-mhz range, and their effect upon a body is potential heating of tissues in MRI.
  • Radiogenic= health effects caused by exposure to ionizing radiation.
  • Radiograph= an x-ray image.
  • Radiographer= an allied health professional who performs diagnostic examinations on patients using a variety of modalities, including radiography, computed tomography, magnetic resonance imaging, mammography, and cardiovascular interventional technology.
  • Radiographic tube rating chart= A guide regarding the most common technical factor combinations that can be used without overloading the tube.
  • Radiography= 1) medical= the use of radiant energy (such as x-rays and gamma rays) to image body systems; 2) industrial= the use of radioactive sources to photograph internal structures, such as turbine blades in jet engines. A sealed radiation source, usually iridium-192 (Ir-192) or cobalt-60 (Co-60), beams gamma rays at the object to be checked. Gamma rays passing through flaws in the metal or incomplete welds strike special photographic film (radiographic film) on the opposite side.
  • Radiography= the production of images using ionizing radiation.
  • Radioisotope (radioactive isotope)= isotopes of an element that have an unstable nucleus. Radioactive isotopes are commonly used in science, industry, and medicine. The nucleus eventually reaches a stable number of protons and neutrons through one or more radioactive decays. Approximately 3,700 natural and artificial radioisotopes have been identified.
  • Radioisotope= a radioactive isotope of an element, used for therapeutic and diagnostic purposes.
  • Radiologic technologist= a person who, under the supervision of a physician radiologist, operates diagnostic imaging equipment and assists radiologists and other health professionals.
  • Radiological dispersal device (RDD)= a device that disperses radioactive material by conventional explosive or other mechanical means, such as a spray. See also dirty bomb.
  • Radiological exposure device (RED)= also called a “hidden sealed source.” An RED is a terrorist device intended to expose people to significant doses of ionizing radiation without their knowledge. Constructed from partially or fully unshielded radioactive material, an RED could be hidden from sight in a public place (e.g., under a subway seat, in a food court, or in a busy hallway), exposing those who sit or pass close by. If the seal around the source were broken and the radioactive contents released from the container, the device could become a radiological dispersal device (RDD), capable of causing radiological contamination.
  • Radiological or radiologic= related to radioactive materials or radiation. The radiological sciences focus on the measurement and effects of radiation.
  • Radiologist= a physician who specializes in medical imaging.
  • Radiology information system (RIS)=  information system used in the radiology department for ordering examinations and reporting results.
  • Radiology information system (RIS)= A database of images and patient records specific to the imaging department.
  • Radiolucent= pertaining to materials that allow x-rays to penetrate with a minimum of absorption.
  • Radiolucent=Allowing the passage of x-radiation. A radiolucent object appears dark on an image.
  • Radioluminescence= The luminescence produced by particles emitted during radioactive decay.
  • Radionuclide Impurity=The presence of other substance(s) in the radiopharmaceutical for nuclear medicine procedures.
  • Radionuclide= an isotope that undergoes radioactive decay. Same as radioisotope.
  • Radionuclide= an unstable and therefore radioactive form of a nuclide.
  • Radiopaque= not permitting the passage of x-rays or other radiant energy.
  • Radiopaque=Preventing the passage of x-radiation. A radiopaque object appears white on an image.
  • Radiopharmaceutical= A drug that is tagged to emit ionizing radiation.
  • Radiopharmaceutical= a radioactive compound produced for use in nuclear imaging.
  • Radium (Ra)= a naturally occurring radioactive metal. Radium is a radionuclide formed by the decay of uranium (U) and thorium (Th) in the environment. It occurs at low levels in virtually all rock, soil, water, plants, and animals. Radon (Rn) is a decay product of radium.
  • Radon (Rn)= a naturally occurring radioactive gas found in soil, rock, and water throughout the United States. Radon causes lung cancer and is a threat to health because it tends to collect in homes, sometimes to very high concentrations. As a result, radon is the largest source of exposure to people from naturally occurring radiation.
  • RAID=Redundant array of inexpensive disks, a computer storage medium with rapid image access time and fault tolerance.
  • Ramping= The process of bringing the superconducting magnet to the necessary temperature by using cryogens.
  • Random-access memory (RAM=) Temporary storage for programming and operating instructions during use that are constantly changing.
  • Rapport= a sense of harmony and understanding underlying a relationship between two persons, which is an essential bond between a therapist and patient.
  • Raster= zigzag electron scanning pattern.
  • Rate of precession= The angular velocity of the nuclear magnetic field.
  • Rated Voltage=The maximum voltage at which an electric component can operate for extended periods without undue degradation or safety hazard.
  • Raw data=Brightness values that have come from the digital image receptor before rescaling occurs.
  • RBE= abbreviation for relative biological effectiveness, a measure of the cell-killing ability of a particular radiation compared with a reference radiation. The reference is 250 kev x-rays.
  • Reactance=A measure of the combined effects of capacitance and inductance on an alternating current. The amount of such opposition varies with the frequency of the current. The reactance of a capacitor decreases with an increase in frequency; the opposite occurs with an inductance.
  • Reading station= computer and monitor generally used by the physician interpreting the digital images.
  • Read-only memory (ROM)= Basic operating instructions that never change.
  • Receiver Operating Characteristic (ROC)=Curve A curve that plots the true-positive fraction versus the false-positive fraction and is used to evaluate imaging performance.
  • Receiver=An electronic package that converts light energy to electrical energy in a fiber optic system. Also refers to a unit that converts an RF signal to another type of signal (e.g. Radio, television). See also Photodetector.
  • Recessive= Genes that manifest themselves only when the person is homozygous for the trait.
  • Reciprocity law failure= Failure to maintain consistent exposures when extremely short or long exposure times are used.
  • Reciprocity law= The density on an x-ray film should remain unchanged as long as the intensity and duration of the x-ray exposure remains unchanged.
  • Reciprocity=The amount of x-ray intensity should remain constant at a specific milliampere-second value despite the milliampere and time combination.
  • Recirculating Electrolytic=A type of electrolytic silver recovery device that recirculates fixer back into the processor after silver reclamation.
  • Recoil electron= The dislodged electron resulting from Compton scattering; also called a Compton electron.
  • Recorded detail= One of the geometric properties of image quality; the degree of geometric sharpness or accuracy of structural lines actually recorded in the image; also referred to as detail, definition, sharpness, spatial resolution.
  • Recorded detail=Sharpness of structures that have been included on the image.
  • Rectal= pertaining to the rectum, the distal portion of the large intestine, about 12 cm long, between the sigmoid colon and the anus. A rectal temperature is taken with the thermometer probe inserted into the rectum.
  • Rectification= The process by which alternating current is changed to pulsating direct current.
  • Rectification=The process of converting an alternating current (AC) into a direct current (DC).
  • Recumbent= lying down or leaning backward.
  • Recumbent=Lying down.
  • Reducing agent= A chemical used in film developing that provides electrons to the silver ions attached to the sensitivity specks of the silver halide crystals.
  • Redundant array of independent disks (RAID)=  composed of several magnetic disks or hard drives that are linked together in an array.
  • Reference axis target angle In mammography, measured from the center of the x-ray beam as in conventional radiography.
  • Reference axis= The angled central ray as used in mammography.
  • Reflection Loss=The part of a signal which is lost due to reflection of power at a line discontinuity.
  • Reflection=The change in direction (or return) of waves striking a surface. For example, electromagnetic energy reflections can occur at an impedance mismatch in a transmission line, causing standing waves.
  • Reflective layer= A layer of material used in an intensifying screen to reflect light toward the film.
  • Reflective layer= layer in the imaging plate that sends light in a forward direction when released in the cassette reader; this may be black to reduce the spread of stimulating light and the escape of emitted light; some detail is lost in this process.
  • Reflex arc= Simple neurologic unit to carry impulses to the central nervous system and impulses to the peripheral nervous system.
  • Refresh rate= measure of how fast the monitor rewrites the screen or the number of times that the image is redrawn on the display each second.
  • Refresh Rate=This refers to how many times each second that a video or computer monitor rewrites or updates the image on the display (also known as the frame rate or vertical scan frequency) of the monitor.
  • Regimen= a strictly regulated therapeutic program such as a diet or exercise schedule.
  • Region of Interest (ROI)=A specified region of the image that is selected for display or analysis.
  • Relative biologic effectiveness (RBE)= The RBE of some test radiation (r) compared with x-rays is defined by the ratio D250/Dr where D250 and Dr are, respectively, the doses of x-rays and the test radiation required for equal biologic effect.
  • Relative Conversion Factor=Measures the amount of light produced by the output phosphor per unit of x-radiation incident on the input phosphor.
  • Relative risk= the ratio between the risk for disease in an irradiated population to the risk in an unexposed population. A relative risk of 1.1 indicates a 10% increase in cancer from radiation, compared with the “normal” incidence.
  • Relative speed= The most useful rating of intensifying screens; expressed with par-screens and film being arbitrarily assigned a relative speed number of 100 as a control point.
  • Relative Speed=A relative number indicating the speed of an intensifying screen imaging system.
  • Reliability=The accuracy, dependability, or validity of the data that has been collected.
  • Rem (roentgen equivalent, man)= a unit of equivalent dose. Not all radiation has the same biological effect, even for the same amount of absorbed dose. Rem relates the absorbed dose in human tissue to the effective biological damage of the radiation. It is determined by multiplying the number of rads by the quality factor, a number reflecting the potential damage caused by the particular type of radiation. The rem is the traditional unit of equivalent dose, but it is being replaced by the sievert (Sv), which is equal to 100 rem.
  • Rem= abbreviation for radiation equivalent in man, the radiation dose equivalent unit in the British system of radiation measurement. Its value is obtained by multiplying the absorbed dose in rad times the weighting factor of the specific type of radiation involved.
  • Rem= Term used to describe the measurement of the biologically equivalent dose.
  • Remnant radiation= the radiation that remains after the x-ray beam passes through an object to produce an image. Same as exit radiation.
  • Renal= pertaining to the kidney.
  • Repeat Analysis=A data collection of repeat images to determine the cause of the repeats so they may be prevented in the future.
  • Repeate=A receiver and transmitter combination used to regenerate an attenuated signal.
  • Repetition time (TR)= The time interval between pulse sequences.
  • Replenishment system= Replaces chemicals that are depleted through the chemical reactions of processing, oxidation, and evaporation.
  • Reproducibility=The same technique setting should always create the same exposure rate at any time.
  • Repulsion-attraction= Law of electrostatics that states like charges repel and unlike charges attract.
  • Res ipsa loquitur= legal doctrine applied when negligence and loss are so apparent they would be obvious to anyone. Literally, “the thing speaks for itself.”
  • Resection= Partial surgical removal of an organ or bone.
  • Resident= a physician in one of the postgraduate years of clinical training (often specialized) after the first, or internship, year.
  • Residual= pertaining to the part of something that remains after removing the bulk of the substance.
  • Resin= A type of silver recovery system that uses acid to form resin ions. The silver is attracted to the resin; the resin is processed to remove the silver.
  • Resistance= The amount of opposition to the current in the circuit.
  • Resistance=In dc circuits, the opposition a material offers to current flow, measured in ohms. In ac circuits, resistance is the real component of impedance, and may be higher than the value measured at dc.
  • Resolution= number of pixels contained on a display.
  • Resolution= The ability to accurately image an object; measured by the ability to see pairs of lines.
  • Resolution=Differentiation of individual structures or details from one another on an image.
  • Resolving power= The ability to accurately image an object; measured by the ability to see pairs of lines.
  • Resonance Frequency=(1) The frequency for which the response of a transducer to an ultrasound beam is a maximum. (2) In magnetic resonance imaging, the frequency at which a nucleus absorbs radio energy when placed in a magnetic field.
  • Resonance=An ac circuit condition in which inductive and capacitive reactances interact to cause a minimum or maximum circuit impedance.
  • Resorption= Bone destruction by osteoclasts.
  • Respiration, respiratory= breathing; the process of the molecular exchange of oxygen and carbon dioxide within the body’s tissues, from the lungs to cellular oxidation.
  • Respiratory arrest= the cessation of breathing, caused by obstruction of the airway by a foreign object or by tracheal or bronchial edema.
  • Respite care= short-term health services to the dependent older adult to provide relief for the primary caregiver.
  • Respondeat superior= legal doctrine that holds employers responsible for negligent acts of their employees that occur in the course of their work. Literally, “let the master respond.”
  • Restrainer= A chemical used in film processing added to the developer to restrict the reducing action to those crystals with sensitivity speck gates.
  • Resulting in extreme weight loss.
  • Resuscitation= the process of sustaining the vital functions of a person in respiratory or cardiac failure while reviving him or her, using techniques of artificial respiration and cardiac massage, correcting acid-base imbalance, and treating the cause of failure.
  • Retention catheter= a type of rectal or urinary catheter with an inflatable cuff that holds the catheter securely in place.
  • Retentivity= The ability of a material to stay magnetized.
  • Retract=To move a structure backward or posteriorly. The shoulder is retracted when it is drawn backward.
  • Retrograde= moving backward; moving or flowing in the opposite direction to that which is considered normal.
  • Retrovirus= any of a family of ribonucleic acid (RNA) viruses containing an enzyme, reverse transcriptase, in the virion.
  • Retrovirus= Any of a family of ribonucleic acid viruses containing the enzyme reverse transcriptase.
  • Reversal The process of reducing the intensity of the,latent image, producing less density.
  • Review workstation= workstation used by other health care personnel to view radiology images.
  • RF=Radio Frequency.
  • RFI=Radio Frequency Interference.
  • Rheostat A device constructed to interrupt a ciruit before a dangerous temperature is reached.
  • Rhodium In mammography, newer anodes are made from this substance.
  • Rickettsia (plural, rickettsiae)= a genus of microorganisms that combine aspects of both bacteria and viruses.
  • Rights-based ethics= system that emphasizes the rights of individuals in a democratic society to be shielded from undue restriction or harm. The rights of some individuals place duties on others.
  • Right-to-left shunting= Ventricular septal defect and overriding aorta causes unoxygenated blood into the left ventricle.
  • Ring topology= network in which the devices are connected in a circle.
  • Ringing Out=The process of locating or identifying specific conductor paths by means of passing a current through selected conductors.
  • Ripening The period of film production during which silver halides are allowed to grow.
  • Risk assessment= an evaluation of the risk to human health or the environment by hazards. Risk assessments can look at either existing hazards or potential hazards.
  • Risk Management=The ability to identify potential risks to patients, employees, and visitors to the healthcare institution and institute processes that minimize these risks.
  • Risk= the probability of injury, disease, or death under specific circumstances and time periods. Risk can be expressed as a value that ranges from 0% (no injury or harm will occur) to 100% (harm or injury will definitely occur). Risk can be influenced by several factors= personal behavior or lifestyle, environmental exposure to other material, or an inborn or inherited characteristic known from scientific evidence to be associated with a health effect. Because many risk factors are not exactly measurable, risk estimates are uncertain.
  • RMS=Root=mean=square.
  • Rocky Mountain spotted fever (RMSF)= a serious tickborne infectious disease occurring throughout the temperate zones of North and South America, caused by Rickettsia rickettsii.
  • Rod cell Cells in the retina of the eye that are sensitive to dim light.
  • Roentgen (R or r)= the standard unit of radiation exposure in the British system of radiation measurement, it is a measurement of radiation intensity in air. The roentgen is equal to the quantity of radiation that will produce 2.08 × 109 ion pairs in a cubic centimeter of dry air.
  • Roentgen (R) Term used to describe the measurement related to exposure; the unit of exposure in air; the quantity of x-rays or gamma rays required to produce a given amount of ionization in a unit mass of air.
  • Roentgen (R)= a unit of exposure to x-rays or gamma rays. One roentgen is the amount of gamma or x-rays needed to produce ions carrying 1 electrostatic unit of electrical charge in 1 cubic centimeter of dry air under standard conditions.
  • Roentgen=The special unit of radiation exposure or intensity.
  • Rotating anode An anode assembly that turns during exposure.
  • Rotor A hollow copper cylinder or cuff that is attached to the anode disk by a molybdenum shaft.
  • Routine maintenance= synonymous with preventive maintenance; maintenance of equipment that occurs before problem occurrences.
  • Rudimentary= Imperfectly developed.
  • S Distortion=An artifact that can occur in image intensifier tubes consisting of a warping of the image along an S-shaped axis.
  • S, sensitivity number= term used by Fuji medical to express exposure.
  • Saccular= Resembling a pouch-like sac.
  • Safe Medical Devices Act (SMDA)=Legislation of 1991 that requires a medical facility to report to the Food and Drug Administration any medical devices that have caused a serious injury or death of a patient (e.g., malfunctioning bed, nonworking defibrillator, nonworking pacemaker, malfunctioning radiation therapy unit) or employee. It also authorizes civil penalties to be imposed on healthcare workers or facilities that do not report defects and failures in medical devices.
  • Safelight=A light source that does not fog film.
  • Sagittal plane=Imaginary plane that passes through the body anteroposteriorly or posteroanteriorly; divides it into right and left sections that are not necessarily equal.
  • Sample=The number of items that are actually measured from a population.
  • Sarcoma= Highly malignant tumors arising from connective tissues.
  • Saturation current As kvp increases, a greater percentage of the thermionically emitted electrons are driven toward the anode.
  • Scale of contrast The number of useful visible densities or shades of gray.
  • Scan Image Uniformity=The uniformity in brightness of an image created with a homogenous phantom.
  • Scanning Examining a particular area for information.
  • Scaphoid fat stripe=Soft tissue structure demonstrated on wrist images located just lateral to the scaphoid.
  • Scatter Plot=A graph that demonstrates a possible correlation between two variables.
  • Scatter radiation= ionizing radiation that occurs as a result of the interaction between the primary x-ray beam and matter. It is emitted from the matter in all directions during the exposure, tending to fog the image and produce a radiation hazard in the room. The patient is the principal source of scatter radiation that occurs during radiography.
  • Scatter radiation=Radiation that has changed in direction from the primary beam because of an interaction with the patient or other structure. Because it is emitted in a random direction, it carries no useful signal or subject contrast.
  • Scattering The interaction of x-ray photons and matter that causes a change in direction of the photons.
  • Scintillation Crystal=A sodium iodide crystal used in scintillation detectors.
  • Scintillation Detector=A radiation detector consisting of a sodium iodide crystal coupled to a photomultiplier tube.
  • Sclerosis An increase in bone hardening resulting from a chronic inflammation of the bone.
  • Sclerosis, sclerotic= a condition characterized by hardening of tissue resulting from any of several causes, including inflammation, the deposit of mineral salts, and infiltration of connective tissue fibers.
  • Sclerosis= Conversion of a portion of bone into an ivory-like, densely opaque mass; an abnormal hardening of body tissues or parts, especially of the walls of arteries.
  • Scoliosis=Spine condition that results in the vertebral column’s curving laterally instead of running straight.
  • Scrap Exposed Film=Exposed and processed film that is not of diagnostic use and is disposed of for silver recovery.
  • Screen lag Delayed phosphorescent emission; also called afterglow.
  • Screen Speed=The amount of light that is emitted from an intensifying screen for a given amount of x-ray exposure.
  • Sealed source= A radioactive source, sealed in an impervious container that has sufficient mechanical strength to prevent contact with and dispersion of the radioactive material under the conditions of use and wear for which it was designed. Generally used for radiography or radiation therapy. May be classified “Special Form” on shipping papers and packages.
  • Second The standard unit of time, abbreviated as s.
  • Secondary barrier A shielding structure that can be struck by scattered and leakage radiation.
  • Secondary coil The coil in which a current is inducted by the primary coil.
  • Secondary health care= an intermediate level of health care that includes diagnosis and treatment, performed in a hospital having specialized equipment and laboratory facilities.
  • Secondary radiation A characteristic photon created by the electron transfer from one shell to another but occurring outside the x-ray target.
  • Secondary stage= Progression of the disease process into the phase that follows the initial stage.
  • Secretory, or postovulatory, phase= Occurs between ovulation and the onset of the menses.
  • Section interval The distance between the fulcrum levels.
  • Section thickness The width of the focal plane which is controlled by the exposure angle.
  • Sedation= an induced state of quiet, calmness, or sleep, as by means of a sedative or hypnotic medication.
  • Segmental fracture= Consists of a segment of the shaft isolated by proximal and distal lines of fracture.
  • Seizure= a hyperexcitation of neurons in the brain leading to a sudden, violent involuntary series of contractions of a group of muscles.
  • Self-induction The ability of an alternating current to switch directions, causing an opposing potential difference to induce against the incoming supply of electrons; allows direct current to flow while at the same time hindering alternating current.
  • Self-rectification Suppressed rectification resulting from only half of the incoming alternating current being converted to pulsating direct current; called half-wave rectification.
  • Semiautomatic mode= postprocessing mode in which the latitude value of the histogram is fixed, and only a small reading area is used; there is no collimation detection, and the proper kv must be used to maintain subject contrast because the latitude value does not change.
  • Semiconductor A material that allows electrons to flow freely under certain conditions (conductor) or that inhibits electron flow under certain conditions (insulator).
  • Semiconductor=In wire industry terminology, a material possessing electrical conductivity that falls somewhere between that of conductors and insulators. Usually made by adding carbon particles to an insulator. Not the same as semiconductor materials such as silicon, germanium, etc. Used for making transistors and diodes.
  • Seminal vesicles= Paired saclike gland that secretes a thick liquid that is rich in fructose for sperm motility.
  • Senile, senility= pertaining to or characteristic of old age or the process of aging.
  • Sensitivity speck An impurity added to silver halide crystals (usually gold-silver sulfide) to act as an electrode that attracts free silver ions during latent image formation.
  • Sensitivity= ability of an analytical method to detect small concentrations of radioactive material.
  • Sensitivity=Indicates the likelihood of obtaining a positive diagnosis in a patient with the disease.
  • Sensitometer An instrument designed to expose a reproducible uniform, optical step wedge onto a film.
  • Sensitometer=An electrical device that exposes the film to a premeasured light source for quality control purposes.
  • Sensitometric curve A radiographic relationship between the amount of exposure and the resultant density on the film; also known as characteristic curve, D log E curve, and Hurter and Driffield curve.
  • Sensitometry The measurement of the characteristic responses of film to exposure and processing.
  • Sensitometry=The study of the relationship between the amount of radiation exposing a film and the optical density that is produced.
  • Sensor=The radiation detector assembly in an automatic exposure control system.
  • Sentinel Event Indicator=An individual event or phenomenon that is significant enough to trigger further review each time it occurs.
  • Sepsis, septic= microbial infection, contamination.
  • Sequestrum= Piece of dead bone that has become separated from the surrounding healthy bone.
  • Series circuit An electric circuit designed to send electrons through various resistance devices by linking them one after the other.
  • Series Circuit=A circuit in which the components are arranged end to end to form a single path for current.
  • Serious Adverse Event=An adverse event that may significantly compromise clinical outcomes or an adverse event for which a facility fails to take appropriate corrective action in a timely manner.
  • Serious Complaint=A report of a serious adverse event.
  • Serosa= Outer layer of a viscus (especially in the alimentary tract).
  • Serpiginous= Having a wavy border.
  • Server= computer that manages resources for other computers, servers, and networked devices.
  • Server-based network= there is a centralized computer (server) that controls the operations, files, and sometimes the programs of the computers (clients) attached to the network.
  • Sestamibi= a radiopharmaceutical used in nuclear imaging to visualize tissues.
  • Sharpening Increase in contrast due to high-pass filtering; also known as edge enhancement.
  • Sharpness One of the geometric properties of image quality; the degree of geometric sharpness or accuracy of structural lines actually recorded in the image; also referred to as detail, definition, recorded detail, spatial resolution.
  • Sharps= any needles, scalpels, or other articles that could cause wounds or punctures to personnel.
  • Shell The energy level occupied by an electron determined by the distance from the nucleus.
  • Shell-type transformer Arrangement of two coils of wire each filled with an iron core in proximity to facilitate induction.
  • Shielding=  the material between a radiation source and a potentially exposed person that reduces exposure.
  • Shim coils Corrective magnetic coils.
  • Shock= Acute peripheral circulatory failure.
  • Shock= an abnormal condition of inadequate blood flow to the body’s peripheral tissues, with life-threatening cellular dysfunction.
  • Shoulder supports A piece of equipment that keeps the patient from sliding off the table when the table is tilted head down.
  • Shredded emulsion is melted at a precise temperature to properly sensitize the crystals.
  • Shunt= to redirect the flow of a body fluid from one cavity or vessel to another, or a device for accomplishing this.
  • Shuttering= used to blacken out the white collimation borders in a digital image, effectively eliminating veil glare.
  • Shuttering=Digital radiography postexposure manipulation that adds a black background around the exposure field, providing a perceived enhancement of image contrast.
  • SI units= the Systeme Internationale (or International System) of units and measurements. This system of units officially came into being in October 1960 and has been adopted by nearly all countries, although the amount of actual usage varies considerably.
  • Sickle cell anemia= Anemia characterized by crescentic red blood cells that contain abnormal hemoglobin molecules and are susceptible to rupture.
  • Side effect= any reaction to or consequence of a medication or therapy other than the therapeutic effect.
  • Sievert (Sv) The product of the absorbed dose in gray and the radiation weighting factor.
  • Sievert (Sv)= a unit used to derive a quantity called dose equivalent. This relates the absorbed dose in human tissue to the effective biological damage of the radiation. Not all radiation has the same biological effect, even for the same amount of absorbed dose. Dose equivalent is often expressed as millionths of a sievert, or micro-sieverts (µsv). One sievert is equivalent to 100 rem. For more information, see “Primer on Radiation Measurement” from CDC.
  • Sigmoidoscope= a fiberoptic instrument used to examine the lumen of the sigmoid colon.
  • Signal=Any visible or audible indication which can convey information. Also, the information conveyed through a communication system.
  • Signal-to-Noise Ratio (SNR)=Used to describe the relative contributions to a detected signal of the true signal and random superimposed signals or noise.
  • Signal-to-noise ratio White noise or “snow.”
  • Signs= Measurable manifestations of a disorder; objective manifestations.
  • Silhouette (cardiac)= Outer border of the heart, seen against the radiolucent lungs.
  • Silicon-controlled rectifier (SCR) A complex semiconductor useful for high-speed switching of the primary high-voltage x-ray circuit; also known as a thyristor.
  • Silver bromide Type of silver halide crystal used to create x-ray films.
  • Silver chloride Type of silver halide crystal used to create x-ray films.
  • Silver iodide Type of silver halide crystal used to create x-ray films.
  • Silver iodobromide Type of silver halide crystal used to create x-ray films.
  • Simple bone cyst (unicameral)= True fluid-filled cyst with a wall of fibrous tissue.
  • Simulator unit Specialized radiography equipment that allows verification of radiation therapy prior to actual treatment.
  • Sine wave The type of curve produced by an AC generator.
  • Single photon emission computed tomography (SPECT)= a computerized nuclear medicine scanning modality similar to PET imaging but involving the injection of radionuclides that emit single photons as opposed to ion pairs as in PET.
  • Single=ended=Unbalanced, such as grounding one side of a circuit or transmission line.
  • Single-phase power Power supply that allows the potential difference to drop to zero with every change in the direction of current flow.
  • Single-Phase=A type of x-ray generator with a single source of alternating current.
  • Single-photon emission computed tomography (SPECT)= Gamma camera moves around the patient and detects the gamma rays produced by the radiopharmaceutical.
  • Single-Photon Emission Computerized Tomography (SPECT)=A nuclear medicine procedure that creates cross-sectional images.
  • Sinus rhythm= a cardiac rhythm stimulated by the sinus (sinoatrial) node. A rate of 60 to 100 beats/min is normal.
  • Sinus tachycardia= a rapid heartbeat generated by discharge of the sinoatrial pacemaker. The rate may be 100 to 180 beats/min in the adult.
  • Sinusoidal=Varying in proportion to the sine of an angle or time function. Ordinary alternating current is sinusoidal.
  • Siphon= using atmospheric pressure to withdraw fluid from a cavity through a tube, or the tube used for this purpose.
  • Situs inversus=Total or partial reversal of the body organs.
  • Six Sigma=A management strategy that seeks to identify and remove the causes of errors in business processes.
  • Skin Effect=The tendency of alternating current to travel only on the surface of a conductor as its frequency increases.
  • Slander= any words spoken with malice that are untrue and prejudicial to the reputation, professional practice, commercial trade, office, or business of another person.
  • Slice Position=The relative position of the image section and the patient.
  • Slice Thickness=The thickness of the image section.
  • Slip ring A device with attached brushes that allows the circuit to remain stationary while the armature rotates without breaking the electrical contact between them.
  • Slow scanning Increases resolution.
  • Small cell (oat cell) carcinomas= Specific type of malignant bronchogenic epithelial neoplasm.
  • Small detector element (DEL)=Element in the DR image receptor that contains the electronic components that store the detected energy.
  • Smoothing A type of low-pass filtering accomplished by averaging each pixel’s value with that of  adjacent pixels.
  • Smoothing= also known as low-pass filtering, the result of averaging each pixel’s frequency with surrounding pixel values to remove high frequency noise.
  • SNR=Signal to Noise Ratio (see also).
  • Social contract theory= the idea that certain persons or groups have relationships that contain inherent expectations, duties, and obligations.
  • Soft copy Images visualized on monitors, either flat panel technology or older cathode ray tubes.
  • Softcopy= reading images on the computer without hardcopy films.
  • Software Programs used on a computer.
  • Solar converter A device that converts solar photons to electrical energy.
  • Solar flare = sudden eruption of hydrogen gas on the surface of the sun that releases a large amount of charged particles.
  • Solar wind = continuous stream of charged particles emitted by the sun in all directions.
  • Solarization The process of reducing the intensity of the latent image, producing less density.
  • Solarization=A decrease in optical density with an increase in exposure. Also known as image reversal.
  • Solenoid = current=carrying coil of wire that acts like a magnet when a current passes through the wire.
  • Solenoid A coil consisting of a series of loops, which serve to increase the flux density.
  • Solid-State Detector=A radiation detector with silicon or germanium crystals.
  • Solution= a mixture of one or more substances dissolved in another substance. The molecules of each of the substances disperse homogenously and do not change chemically.
  • Solvent Chemicals used in developing film suspended in water.
  • Somatic Describes the effects of radiation that appear in the individual who was irradiated.
  • Somatic effects= effects of radiation that are limited to the exposed person, as distinguished from genetic effects, which may also affect subsequent generations.
  • Somatic nervous system= Supplies the striated skeletal muscles.
  • Sonography= the process of imaging deep structures of the body by measuring and recording the reflection of pulsed or continuous high-frequency sound waves.
  • Source-image distance (SID)= the distance between the x-ray tube target and the image receptor, measured along the central ray.
  • Source–image receptor distance (SID)=Distance from the anode’s focal spot to the IR.
  • Source–object distance (SOD)=Distance from the anode’s focal spot to the patient.
  • Source–skin distance (SSD)=Distance from the source of radiation (anode) to the patient’s skin. Good radiation practices dictate that this distance must be at least 12 inches (30cm) to prevent unacceptable entrance skin exposure.
  • Space charge cloud The ejection of electrons from the surface of the wire due to increased heat, causing an electron cloud; also called thermionic emission.
  • Space charge effect As more and more electrons build up in the area of the filament, their negative charges begin to oppose the emission of additional electrons.
  • Spasm, spasmodic= an involuntary muscle contraction of sudden onset.
  • Spatial frequency resolution= amount of detail or sharpness in a digital image.
  • Spatial frequency=Used to define spatial resolution; refers to how often the number of details change in a set amount of space. It is expressed as line pairs per millimeter (lp/mm).
  • Spatial Linearity=The ability of a gamma camera system to produce a linear image with straight lines corresponding to the same straight lines of the bar pattern OR the amount of geometric distortion in the image as affected by the homogeneity of the main magnetic field and the linearity of the magnetic field gradients.
  • Spatial resolution One of the geometric properties of image quality; the degree of geometric sharpness or accuracy of structural lines actually recorded in the image; also referred to as detail, definition, sharpness, recoded detail. In digital images, it can be expressed in terms of three dimensions of the image.
  • Spatial resolution=Ability of an imaging system to distinguish small adjacent details from each other in the image.
  • Spatial Resolution=The ability of an imaging process to distinguish small, adjacent, high-contrast structures in the object.
  • Special Nuclear Material (SNM)= Plutonium and uranium enriched in the isotope uranium-233 or uranium 235.
  • Specific absorption rate (SAR) The absorption of RF radiation.
  • Specific activity= Unit pertaining to the disintegrations per gram of a radioisotope
  • Specificity=Indicates the likelihood of a patient obtaining a negative diagnosis when no disease is present.
  • Spectral Bandwidth=The difference between wavelengths at which the radiant intensity of illumination is half its peak intensity.
  • Spectral emission An indication of the precise wavelength of light emitted by the phosphor.
  • Spectral Matching=The matching of film sensitivity with the color of light emitted by the intensifying screen.
  • Spectrum=A display of electromagnetic energy on the basis of wavelength and frequency.
  • Spectrum=Frequencies that exist in a continuous range and have a common characteristic. A spectrum may be inclusive of many spectrums (e.g., the electromagnetic radiation spectrum includes the light spectrum, radio spectrum, infrared spectrum, etc.).
  • Specular Reflection=A type of reflection coming from the surface of an electronic display that produces a mirror image of the light source creating it
  • Speed exposure point The log exposure that will produce the speed point for a given film.
  • Speed Indicator=The step closest to 1 above the base + fog on a sensitometric test film.
  • Speed of Light ( c )=Approximately 2.998 x 10^8 meters per second.
  • Speed point The point on the D log E curve where a density of ODD 1.0 + b + f is achieved.
  • Speed= in conventional radiography, speed is determined by the size and layers of crystals in the film and screen; computed radiography system “speeds” are a reflection of the amount of photostimulable luminescence given off by the imaging plate while being scanned by the laser.
  • Spermatogenesis= Formation of sperm.
  • Spherocytosis= Anemia due to erythrocytes that have a circular rather than a biconcave shape, making them fragile and susceptible to rupture.
  • Sphygmomanometer= an instrument for indirect measurement of blood pressure. It consists of an inflatable cuff that fits around the arm, a bulb for controlling air pressure within the cuff, and a mercury or aneroid manometer.
  • Spin magnetic moment The magnetic effect created by electrons spinning on their axes.
  • Spina bifida occulta= Mild form in which there is a splitting of the bony neural canal but no clinical symptoms.
  • Spinal tap= a procedure that involves the insertion of a needle into the subarachnoid space to withdraw spinal fluid. May be performed to inject a contrast medium for myelography. Same as lumbar puncture.
  • Spin-echo (SE)= Most common pulse sequence used in MRI using 90° radiofrequency pulses to excite the magnetization and one or more 180° pulses to refocus the spins to generate signal echoes.
  • Spin-lattice relaxation time (T1) The time required for precessing spins to align with the constant external magnetic field to 63 percent of the maximum possible strength.
  • Spin-spin relaxation time (T2) The time required after precessing spins have aligned at an angle to the external magnetic field due to an RF pulse for them to lose 63 percent of their coherence due to interactions between the spins.
  • Spiral fracture= Encircles the shaft of a long bone.
  • Spirochete= Spiral type of bacterium of the genus Spirochaeta.
  • Spirometry= Measure of lung capacity using a spirometer.
  • Splitter=A device that send the signal from one source to two or more receiving devices by allocating a portion of the signal to each receiver (e.g. Cable TV splitter). A device that divides a high bandwidth signal into two or more lower bandwidth signals, each carrying a selected frequency range.  Users connected to a DSL line, for example, may have a splitter installed at their home or business to divide the incoming signal into low frequencies to send to their phone and high frequencies for data to the computer.
  • Spondylolisthesis= Spondylolysis with displacement of vertebral alignment.
  • Spondylolysis= Cleft in the pars interarticularis situated between the superior and inferior articular processes of the vertebra without displacement.
  • Spontaneous abortion= a termination of pregnancy before the twentieth week of gestation as a result of abnormalities of the conceptus or maternal environment. Also called miscarriage.
  • Spontaneous combustion= the occurrence of fire when a chemical reaction in or near a flammable material causes sufficient heat.
  • Spore= a reproductive unit of some genera of fungi or protozoa. Also, a common term for endospore, a form assumed by some bacteria that is resistant to heat, drying, and chemicals.
  • Squamous cell carcinoma= Cancer in which tumor cells resemble stratified squamous epithelium.
  • Square law=Law that states that a change in the SOD can be compensated for by changing the mas by the factor SID squared.
  • Stable nucleus= the nucleus of an atom in which the forces among its particles are balanced.
  • Stable= Resistant to change.
  • Staghorn calculus= Renal calculi filling the entire renal pelvis of the kidney.
  • Staging= Determination of the amount of spread of a neoplasm, necessary to select appropriate therapy and to predict the future course of a disease.
  • Standard Deviation=The amount of variance in a sample.
  • Standby replenishment A type of flood replenishing system used for low-volume systems; controlled by a timer that floods the developer and fixer tanks with replenisher at regular intervals.
  • Standby switch Shuts down a processing system after 2 minutes of inactivity; must be manually activated to bring the unit up for processing.
  • Standing order= a written document containing rules, policies, procedures, regulations, and orders for the conduct of patient care in various stipulated clinical situations.
  • Standing Wave Ratio (SWR)=A ratio of the maximum amplitude to the minimum amplitude of a standing wave stated in current or voltage amplitudes. See also Standing Wave.
  • Standing Wave=The stationary pattern of waves produced by two waves of the same frequency traveling in opposite directions on the same transmission line. The existence of voltage and current maxima and minima along a transmission line is a result of reflected energy from an impedance mismatch.
  • Star topology= network that has the devices connected to a central hub or switch.
  • Starter solution A solution of acetic acid and potassium bromide that is added to the replenisher solution when starting a fresh tank of developer.
  • Stasis= Stagnation of some fluid in the body (as of blood in veins); reduced peristalsis of the intestines resulting in the retention of feces.
  • STAT= immediately, at once.
  • Static Charge=An electrical charge that is bound to an object. An unmoving electrical charge.
  • Static discharge= The result of electrons jumping the gap between two objects, one negatively charged and one positively charged, resulting in the equalization of the charges of the two objects.
  • Static Electricity=Electrical charges created by friction, which can cause artifacts on unprocessed film.
  • Stationary= anode An anode assembly that is immobile.
  • Stator= Induction-motor electromagnets that turn the anode.
  • Status epilepticus= a medical emergency characterized by continuous seizures occurring without interruptions.
  • Steel = an alloy of iron, which is mostly pure iron combined with some other elements, such as carbon.
  • Stenosis= an abnormal condition characterized by the constriction or narrowing of an opening or passageway in a body structure.
  • Stenosis= Narrowing.
  • Stent= a tubular device for supporting hollow structures during surgical anastomosis or for holding arteries open during and/or after angioplasty.
  • Step wedge= A type of penetrometer that is wedge shaped and has different levels or steps.
  • Step-down transformer= A device used to decrease the voltage from the primary to the secondary coil.
  • Step-up transformer= A device used to increase the voltage from the primary to the secondary coil.
  • Sterile conscience= the awareness of sterile technique and the responsibility for notifying those in charge whenever contamination occurs.
  • Sterile corridor= the area of an operating room between the patient drape and the instrument table. Access to this area is permitted only to those wearing sterile attire.
  • Sterile field= a specified area, such as within a tray or on a sterile towel, that is considered free of microorganisms.
  • Sterile, sterilization= free of living microorganisms; the process of destroying all microorganisms.
  • Sterilization= treatment of items with heat, gas, or chemicals to make them germ-free.
  • Steroid= any of a large number of hormonal substances with a similar basic chemical structure, produced mainly in the adrenal cortex and gonads, that may be used to treat inflammatory conditions or as antiallergic medication.
  • Stochastic effect= an effect that occurs on a random basis independent of the size of dose. The effect typically has no threshold and is based on probabilities, with the chances of seeing the effect increasing with dose. If it occurs, the severity of a stochastic effect is independent of the dose received. Cancer is a stochastic effect.
  • Stochastic effect=Biologic response to radiation in which the chance of occurrence of the effect, rather than the severity of the effect, is proportional to the dose of radiation received.
  • Stochastic effects= Results of radiation exposure for which no threshold dose of radiation exists (e.g., cancer, genetic effects).
  • Stochastic= describes biologic radiation effects that are random and unpredictable; their likelihood is dose-dependent, but not their severity. There is no threshold amount of exposure necessary to produce these effects.
  • Stoma= a pore, orifice, or opening on a surface; the external opening of a colostomy or ileostomy.
  • Straight line portion= The useful range of densities on the D log E curve.
  • Stress, or fatigue, fracture= Fracture caused by repetitive stresses applied to the bone.
  • Stridor= an abnormal, high-pitched sound caused by an obstruction in the trachea or larynx, usually heard during inspiration.
  • String Test=A quality control test for Doppler ultrasound equipment.
  • String theory= The idea that matter behaves differently depending on the vibration on the string-like matter.
  • Stroke= an abnormal condition of the brain characterized by a rupture or obstruction of an artery of the brain. Same as cerebrovascular accident (CVA).
  • Stroke= Cerebrovascular accident; denotes a sudden and dramatic focal neurologic deficit.
  • Stroma= Supporting tissue of the matrix of art organ.
  • Strontium (Sr)= a silvery, soft metal that rapidly turns yellow in air. Sr-90 is one of the radioactive fission materials created within a nuclear reactor during its operation. Stronium-90 emits beta particles during radioactive decay.
  • Structural protective barriers= Fixed x-ray facilities that are constructed of materials having effective x-ray attenuating properties and are of thickness sufficient to reduce exposures to desired levels.
  • Structural Return Loss=Magnitude of the internal cable reflections, measured in decibels, relative to the actual cable impedance, not the system impedance. Measure of signal reflections caused by the structure of the cable without the additional reflections from any impedance mismatch between the cable and the measuring equipment. Measure of internal cable reflections using a reference impedance in the measuring equipment that is adjusted to the nominal or average impedance of the cable. See also Return Loss
  • Structures.
  • Stupor, stuporous= a state of unresponsiveness in which a person seems unaware of the surroundings.
  • Subarachnoid space= Space beneath the arachnoid and above the pia mater, which contains cerebrospinal fluid.
  • Subcellular= pertaining to a lower level of organization, structure, and function than that of a cell.
  • Subchondral= Just beneath the articular margin.
  • Subcutaneous= beneath the skin.
  • Subdiaphragmatic= beneath the diaphragm.
  • Subject contrast= The degree of differential absorption resulting from the differing absorption characteristics of the tissues in the body.
  • Subject contrast=Contrast caused by the x-ray attenuating characteristics (atomic density and number, and thickness) of the subject being imaged.
  • Subject density= The impact the subject (patient) has on the resulting radiographic density.
  • Subject detail= The impact that the position of the structures of interest with the body has on the recorded detail.
  • Subject distortion= The impact that the position of the structures of interest within the body has on distortion.
  • Subliminal= taking place below the threshold of sensory perception or outside the range of conscious awareness.
  • Sublingual= pertaining to the area beneath the tongue.
  • Subluxation= Incomplete or partial dislocation.
  • Subluxation=Partial dislocation.
  • Substance= A material that has a definite and constant composition.
  • Sulci= Shallow depressions on the surface of an organ.
  • Sulfurization=A buildup of sulfur on the electrodes in an electrolytic silver recovery unit as a result of incorrect amperage setting.
  • Super user= someone trained within the hospital to help troubleshoot and teach others to use the PACS.
  • Superadditivity= When two reducing agents are combined, forming a PO developer, their reducing ability is the sum of their independent abilities.
  • Supercoat= A layer of hard, protective gelatin designed to prevent the soft emulsion underneath from being physically or chemically abused due to handling.
  • Superconductor= A material that allows electrons to flow freely.
  • Superimpose=To lie over or above an anatomic structure or object.
  • Superior (supero-)=Refers to a structure within the patient’s torso that is situated closer to the head; used when comparing the locations of two torso structures. The thoracic cavity is superior to the peritoneal cavity.
  • Supernumerary kidney= An extra kidney.
  • Supination=Rotating or turning the upper extremity laterally until the hand’s palmar surface is facing upwardly or anteriorly.
  • Supplier=One who provides goods or services.
  • Support layer= semirigid material in the imaging plate that gives the imaging sheet some strength.
  • Suppository= an easily melted medicated mass for insertion into the rectum, urethra, or vagina.
  • Supraorbital=Above the orbit.
  • Supraspinatus outlet=Opening formed between the lateral clavicle, acromion process, and superior scapula when the patient is positioned for a tangential outlet projection of the shoulder.
  • Surface burst= a nuclear weapon explosion that is close enough to the ground for the radius of the fireball to vaporize surface material. Fallout from a surface burst contains very high levels of radioactivity.
  • Surface coil= An RF coil shaped to conform to the body part being imaged.
  • Surfactant= Agent that lowers the surface tension.
  • Surge=A temporary and relatively large increase in the voltage or current in an electric circuit or cable. Also called transient.
  • Surgical resection= partial removal of a structure or organ by surgery.
  • Suspension= a liquid in which small particles of a solid are dispersed, but not dissolved, and in which the dispersal is maintained by stirring or shaking the mixture. If left standing, the solid particles settle at the bottom of the container.
  • Sweep Test=Testing a characteristic of a cable or device across a range of frequencies. In cable, it usually implies return loss or structural return loss (see also).
  • Symmetrical=Refers to structures on opposite sides demonstrating the same size, shape, and position.
  • Symptoms= Subjective manifestations; the patient feels.
  • Synapse= Point of contact between two neurons for impulses to flow.
  • Syncope= a brief lapse in consciousness caused by transient cerebral hypoxia. Same as fainting.
  • Syndrome= Indicates the presence of a combination of symptoms that commonly occur together and are related to a single cause.
  • Synergism=The action of two agents working together is greater than the sum of the action of the agents working independently.
  • Synergistic effect= the acting or working together of two or more components, as when medications produce a combined effect.
  • Syphilis= a sexually transmitted disease caused by the spirochete Treponema pallidum, characterized by distinct stages of effects over a period of years.
  • System architecture= hardware and software infrastructure of the system’s workflow.
  • Systeme International d’Unites (SI units)= An international system of units based on the metric system.
  • Systemic circulation= High-pressure system that carries blood to the organs and extremities.
  • Systemic effect= involving the whole body rather than a localized area or regional part of the body.
  • Systole= Phase in which the heart contracts.
  • Systolic= pertaining to systole, or the blood pressure measured at the peak of ventricular contraction.
  • T1-weighted image= Equilibrium—high-energy protons return to the low-energy state.
  • T2-weighted image= Image relies upon local dephasing of spins.
  • Tachycardia= abnormally rapid pulse; a condition in which the heart beats at a rate greater than 100 beats/min.
  • Tachypnea= an abnormally rapid respiratory rate (more than 20 breaths per minute), as seen with hyperpyrexia.
  • Tailing= If the silver recovery is not sufficient, a second process is undergone to process the solution after it has gone through the first unit.
  • Tailings= waste rock from mining operations that contains concentrations of mineral ore that are too low to make typical extraction methods economical.
  • Talar dome=Dome shape formed by the most medial and lateral aspects of the talar’s trochlear surface when they are in a lateral position.
  • Tape= magnetic tape cartridges used for long-term storage archives.
  • Target Composition=Refers to the elemental composition of the x-ray tube anode.
  • Target interaction= The actions that take place when the electrons strike their target or focal spot.
  • Target= The portion of the anode where the high-voltage electron stream will impact.
  • Targeting= A magnification technique which permits an area of interest to be selected for reformatting.
  • Tarsi sinus=Opening between the calcaneus and talus
  • TDMA=Time Division Multiple Access.
  • Technetium Pertechnetate=A radionuclide used in nuclear medicine procedures that consists of technetium-99m.
  • Technetium-99m=The isotope of technetium whose primary gamma ray has an energy of 140 kiloelectron volts.
  • Telangiectasia= Vascular lesion formed by dilation of a group of small blood vessels.
  • Teleradiology= moving images via telephone lines to and from remote locations.
  • Temperature control system= The part of the automatic processing unit that maintains all three solutions at compatible temperatures.
  • Temperature= A measure of thermal energy.
  • Temperature=A measure of the average kinetic energy in atoms and molecules of matter.
  • Temporal= pertaining to the sides of the skull, anterior to the ears. The temporal arteries lie beneath the sides of the scalp in the temporal region. A temporal artery thermometer measures temperature from the temporal artery by scanning the forehead and temporal region with an infrared sensor.
  • Temporary magnet = a material whose magnetic domains align under the influence of another magnet or electric current, but can’t be maintained. Temporary magnets have a low coercivity.
  • Tepid= moderately warm to the touch; “lukewarm.”
  • Teratogenic effects= birth defects that are not passed on to future generations, caused by exposure to a toxin as a fetus.
  • Teratoma= Neoplasm composed of various kinds of embryonic tissue.
  • Terminal Electrolytic=An electrolytic silver recovery device in which the used fixer is removed for disposal.
  • Terrestrial radiation= radiation emitted by naturally occurring radioactive materials, such as uranium (U), thorium (Th), and radon (Rn) in the earth.
  • Tertiary health care= a specialized, highly technical level of health care that includes diagnosis and treatment of disease and disability in sophisticated, large research and teaching hospitals.
  • Tertiary= Third in rank or order.
  • Tesla (T)= The unit used for measuring magnetic flux density.
  • Testicular dysgenesis= Characterized by small testes that fail to mature or produce sperm and testosterone.
  • Testosterone= Stimulates the development and activity of the male accessory sex organs.
  • Tetanus= an acute, potentially fatal infection of the central nervous system caused by an exotoxin, tetanospasmin, elaborated by an anaerobic bacillus, Clostridium tetani.
  • Thalamus= Portion of the brain that receives and processes sensory information and relays it to the cerebral cortex.
  • Thalassemia= Hemolytic anemia due to a defect in hemoglobin formation.
  • That allow study of the urological and genital
  • The Joint Commission (TJC)=A private agency (formerly known as JCAHO) responsible for accreditation of healthcare systems.
  • The joint commission= organization that accredits health care organizations, such as hospitals, clinics, and labs.
  • Therapeutic effect= the desired benefit of a medication, treatment, or procedure.
  • Therapeutic= Methods used to treat and rehabilitate a disease, disorder, or traumatic injury.
  • Therapy, therapeutic= the treatment of any disease or pathological condition.
  • Thermal energy= The result of the motion of atoms and molecules; also known as heat.
  • Thermal noise= Results from the increase of Brownian motion, which, in turn, increase body temperature.
  • Thermionlc emission= The ejection of electrons from the surface of the wire due to increased heat, causing an electron cloud; also called the space charge cloud.
  • Thermoluminescent dosimeter (TLD)= Small chips of thermoluminescent material, usually lithium fluoride. When exposed to radiation, the chips enter a metastable state; when exposed to heat they give off visible light.
  • Thermoluminescent Dosimeter (TLD)=A type of radiation detector with crystals such as lithium fluoride that release light when heated that is proportional to the amount of incident radiation.
  • Thermonuclear device= a “hydrogen bomb.” A device with explosive energy that comes from fusion of small nuclei, as well as fission.
  • Thick-client= computer that can work independently from the network and can process and manage its own files.
  • Thin-client= device that is found on a network that requests services and resources from a server.
  • Thin-film transistor (TFT)=  photosensitive array, made up of small (about 100 to 200μm) pixels, converts the light into electrical charges.
  • Thin-film transistor (TFT)=Component in the DR imaging receptor that receives the remnant radiation.
  • Thin-Film Transistor (TFT)=Switches for each pixel of an array connected to circuitry that allows all switches in a row of the array to be operated simultaneously.
  • Thoracentesis= surgical removal of fluid from the pleural space.
  • Thoracotomy= a procedure involving a surgical opening into the thoracic cavity.
  • Thoreaus filter= A type of compound filter consisting of tin, copper, and aluminum, in that order, typically used in radiation therapy.
  • Thorium (Th)= a naturally occurring radioactive metal found in small amounts in soil, rock, water, plants, and animals. The most common isotopes of thorium are thorium-232 (Th-232), thorium-230 (Th-230), and thorium-238 (Th-238).
  • Thready= descriptive of an abnormal pulse that is weak, somewhat difficult to palpate, and often fairly rapid; the artery does not feel full, and the rate may be difficult to count.
  • Three-phase 12-pulse= A full-wave rectification produces a voltage ripple never dropping below 90-95 percent of the peak kilovoltage setting.
  • Three-phase power= Power supply generated as each wave peaks drops toward zero. The overall potential difference is boosted back to peak by the next phase wave; the sum of the phasing never drops to zero.
  • Three-phase six-pulse= A full-wave rectification produces a voltage ripple that produces six usable pulses per cycle.
  • Three-Phrase=An alternating-current power source made up of three single-phase currents that are staggered by 120 degrees.
  • Threshold detection= A visual phenomenon involving the perception of extremely small or faint details.
  • Threshold=A pre-established level of performance applied to a specific indicator.
  • Thrombosis= an abnormal vascular condition in which a clot (thrombus) develops within a blood vessel of the body.
  • Thrombus (plural, thrombi)= an aggregation of platelets, fibrin, clotting factors, and the cellular elements of the blood attached to the interior wall of a vein or artery.
  • Thrombus= Blood clot in the vascular system.
  • Thymoma= Tumor originating from the thymus gland.
  • Thyristor= A complex semiconductor useful for high-speed switching of the primary high-voltage x-ray circuit; also known as a silicon-controlled rectifier (SCR).
  • Thyroxine= Hormone influencing metabolic rate.
  • Tier= level, layer, or division of something.
  • Tilting= A piece of equipment that is movable and
  • Time of Day Variability=A possible variable in sensitometric testing in which test films are processed at different times during the day, varying in optical density.
  • Timed replenishment= A type of flood replenishing system used for low-volume systems; controlled by a timer that floods the developer and fixer tanks with replenisher at regular intervals.
  • Timer= Device used to end the exposure at an
  • Tissue Equalization=Image processing that compensates for varying breast tissue densities so that the entire breast (from the chest wall to the skin line) can be visualized in a single image.
  • Tomographic amplitude= The total distance the tube travels; tomographic arc or tomographic angle.
  • Tomography unit= Specialized radiography equipment that allow movement in an arc during exposure.
  • Tomography= A radiographic technique that employs motion to show anatomical structures lying in a plane of tissue while blurring or eliminating the detail in images of structures above and below the plane of interest.
  • Tomography=A radiographic process whereby specific slices of the body are imaged.
  • Topical= mode of medication administration in which the medication is applied to the surface of a part of the body.
  • Topology= physical (geometric) layout of the connected devices on a network.
  • Tort= a civil wrong, such as negligence, false imprisonment, assault, and battery.
  • Tortuous= Full of twists, turns, or curves.
  • Torus (buckle) fracture= One cortex is intact, with buckling or compaction of the opposite cortex.
  • Total brightness gain= A measurement of the increase in image intensity achieved by an image intensification tube.
  • Total Effective Dose Equivalent (TEDE)= The sum of effective dose equivalent from external radiation and the committed effective dose equivalent from inhaled and ingested radioactive material. Quoted in units of rem.
  • Total filtration= The sum of inherent and added filtration.
  • Total quality management (TQM)=  see continuous quality improvement.
  • Total repeat rate= A figure that is calculated as a percentage of the total number of images produced during the period of the study.
  • Tourniquet= a device, usually a wide, constricting band of elastic material, wrapped around a limb to restrict blood flow. It is applied to a limb to control hemorrhage or to enhance accessibility of veins for venipuncture.
  • Toxicity, toxic= effect resulting from an excess amount of medication in the blood, these effects may be caused by excessive use of medications, overdose, impaired excretion, or an idiosyncratic reaction to the medication.
  • Toxin, toxic= a poison; having a poisonous effect.
  • Toxoid= Chemically altered toxin.
  • Trabeculae= Supporting or anchoring strands of connective tissue within body structures.
  • Trabecular pattern=Supporting material within cancellous bone. It is demonstrated on an image as thin white lines throughout a bony structure.
  • Tracheostomy= an opening through the neck into the trachea through which an indwelling tube may be inserted to ventilate the patient.
  • Tracheotomy= the procedure of making an incision into the trachea through the neck below the larynx, performed to gain access to the airway below a blockage caused by a foreign body, tumor, or edema.
  • Traction= Process of placing tension between two structures.
  • Traction= the process of putting a limb, bone, or group of muscles under tension by means of weights and pulleys to align or immobilize the part or to relieve pressure on it.
  • Tranquilizer= a drug prescribed to calm anxious or agitated people, ideally without decreasing their consciousness. A common term for benzodiazepines.
  • Transducer= a hand-held device, used in diagnostic sonography, that sends and receives a sound wave signal. It changes electrical impulses into sound waves, receives the reflected sound wave, and converts it back into electrical energy.
  • Transducer=A device for converting one form of energy to another, such as mechanical energy to electrical energy.
  • Transfer Impedance=For a specified cable length, transfer impedance relates to a current on one surface of a shield to the voltage drop generated by this current on the opposite surface of the shield. Transfer impedance is used to determine shield effectiveness against both ingress and egress of interfering signals. Cable shields are normally designed to reduce the transfer of interference = hence, shields with lower transfer impedance are more effective than shields with higher transfer impedance.
  • Transformer= A device in which two coils are placed near one another without electrical connection. The number of turns in the coils differs, causing a change in current in the secondary coil; this serves to either increase or decrease the voltage.
  • Transient ischemic attack (TIA)= an episode of cerebrovascular insufficiency, usually associated with partial occlusion of an artery by an atherosclerotic plaque or an embolism.
  • Transitional vertebra= Vertebra with characteristics of another spinal region.
  • Transmission Line Cable=Two or more conductors placed within a dielectric material in such a way as to control the electrical characteristics.
  • Transmission Line=An arrangement of two or more conductors, a coaxial cable, or a waveguide used to transfer signal energy from one location to another.
  • Transmitted Light=The amount of viewbox light that is transmitted through a film image.
  • Transmitter=The electronic package that converts electrical energy to light energy in a fiber optic system. Also refers to equipment that generates RF or electrical signals for transmission through the air or space or over a transmissions line.
  • Transport racks= Part of the automatic processing
  • Transport system consisting of three rollers designed to move film through a processing tank.
  • Transport system= Part of the automatic processing system designed to move a film through developer, fixer, wash, and dryer sections of the processor.
  • Transuranic= pertaining to elements with atomic numbers higher than uranium (92). For example, plutonium (Pu) and americium (Am) are transuranics.
  • Transverse foreshortening=Short axis of a structure appears disproportionately shorter on the image than the long axis.
  • Transverse fracture= Runs at a right angle to the long axis of a bone.
  • Transverse, horizontal, or crosswise (CW)=Refers to a plane that is at a 90-degree angle from the longitudinal axis of the anatomic structure or object being discussed. The transverse axis of a 14- × 17-inch (35- × 43-cm) IR would parallel the shorter (14-inch or 35-cm) length. The transverse axis on a patient’s thorax would be perpendicular to the midsagittal plane.
  • Trauma= physical injury caused by violent or disruptive action or by the introduction into the body of a toxic substance.
  • Tremor= rhythmic, purposeless movements resulting from the involuntary alternating contraction and relaxation of opposing groups of skeletal muscles.
  • Trend Chart=A graph that pictorially demonstrates whether key indicators are moving up or down over a given period. Also called a run chart.
  • Triage, radiological= actions intended to sort people according to whether they have been exposed to radioactive material at a level that will definitely have an effect on their health (i.e., causing deterministic injuries like tissue reactions or acute radiation syndrome); or whether they may have been exposed to radioactive material at lower levels that might impart a long-term health risk (i.e., stochastic health effects or cancer induction in the future); or whether they are in the potentially large group of people whose exposures are very unlikely to have any effect on health, or who were not exposed at all.
  • Triage= in the case of disaster or multiple victims needing attention, the process of identifying the victims, performing initial examinations, and assigning priorities for further care.
  • Triage= The use of simple procedures for rapidly sorting affected people into groups so as to expedite treatment and maximize the effective use of medical and monitoring supplies.
  • Trichomoniasis= a vaginal infection caused by the protozoan Trichomonas vaginalis.
  • Tricuspid valve= Valve between the right atrium and right ventricle that has three cusps.
  • Trigone= Triangular area of the posterior bladder, between the openings for the ureters and urethra.
  • Tripod fracture= Fractures of the zygomatic arch and the orbital floor or rim combined with separation of the zygomaticofrontal suture.
  • Triradiate= Radiating in three directions.
  • Trisomy 21= see Down syndrome.
  • Trisomy= Presence of an additional (third) chromosome.
  • Tritium= (chemical symbol H-3) a radioactive isotope of the element hydrogen (chemical symbol H).
  • Trocar= a sharp, pointed rod that fits inside a tube. It is used to pierce the skin and the wall of a cavity or canal in the body to aspirate fluids, to instill a medication or solution, or to guide the placement of a soft catheter or fiberoptic device.
  • Trophoblastic= Relating to the layer by which the fertilized ovum is attached to the uterine wall and from which the developing embryo receives its nourishment.
  • Trough filter= A type of compensating filter used to even out densities such as in the mediastinum.
  • Troy Ounce=A unit of weight used for precious metals such as silver; 14.58 troy ounces = 16 standard ounces.
  • Tube rating chart= Provides a guide regarding the most common technical factor combinations that can be used without overloading the tube.
  • Tubercle= a nodule or a small eminence, such as that on a bone or the nodules caused by tuberculosis.
  • Tuberculin= referring to or related to a tubercle or to tuberculosis.
  • Tuberculosis (TB)= a chronic granulomatous infection caused by an acid-fast bacillus, Mycobacterium tuberculosis. It is generally transmitted by the inhalation or ingestion of infected droplet nuclei and usually affects the lungs, although infection of multiple organ systems occurs.
  • Tuberculosis= Infection by mycobacteria, causing inflammation of the lungs.
  • Tuberculous arthritis= Chronic indolent infection with a slow progressive course caused by tuberculosis.
  • Tumor= An abnormal new growth in tissue.
  • Tungsten= chemical symbol W; a metallic element. It has the highest melting point of all metals and is used as a target material in x-ray tubes and as filament material in both x-ray tubes and incandescent light bulbs.
  • Twisted-pair wire= network communication medium that consists of four twisted pairs of copper wire that are insulated and bundled together with an rj-45 termination.
  • Tympanic membrane= a thin, semitransparent membrane in the middle ear that transmits sound vibrations to the internal ear by means of the auditory ossicles. Same as ear drum. A tympanic thermometer measures temperature by means of a probe inserted into the ear.
  • Typhoid fever= a bacterial infection usually caused by Salmonella typhi, transmitted by contaminated milk, water, or food.
  • Typhus fever= any of a group of acute infectious diseases caused by various species of Rickettsiae and usually transmitted from infected rodents to humans by the bites of lice, fleas, mites, or ticks.
  • UHF=Ultra High Frequency. International Telecommunication Union designation for the 300=3000 mhz band of frequencies.
  • Ulceration= Destruction of tissue creating an opening within a structure.
  • Ulcerative colitis= a chronic, episodic, inflammatory disease of the large intestine and rectum.
  • Ulcerogenic islet cell tumors (gastrinomas)= Tumor found in the pancreas and duodenum that is associated with peptic ulcers.
  • Ulnar deviation=While maintaining a PA projection, the distal hand is turned toward the ulnar side as much as the wrist will allow.
  • Ultra density optical disk (UDO)=  new generation mod; uses blue laser technology in its read and write activities.
  • Ultrasound= Images produced by high-frequency sound waves emitted from the transducer that are echoed back to produce an image
  • Ultraviolet Radiation=A type of electromagnetic radiation in between visible light and x-rays.
  • Umbilical artery catheter (UAC)=Found only in neonates because the cord has dried up and fallen off in older infants. Is used to measure oxygen saturation.
  • Umbilical vein catheter (UVC)=Catheter used to deliver fluids and medications.
  • Undifferentiated= Without form.
  • Undisplaced fracture= The bone is without angulation or separation.
  • Uniformity Correction Flood=A quality control procedure for nuclear medicine equipment.
  • Unilateral renal agenesis= Absence of a kidney.
  • Unilateral=One side.
  • UNSCEAR= United Nations Scientific Committee on the Effects of Atomic Radiation.
  • Unstable nucleus= a nucleus that contains an uneven number of protons and neutrons and seeks to reach equilibrium between them through radioactive decay (i.e., the nucleus of a radioactive atom).
  • Unstable= As a result of a fracture, alignment is uncertain.
  • Uranium (U)= a naturally occurring radioactive element whose principal isotopes are uranium-238 (U-238) and uranium-235 (U-235). Natural uranium is a hard, silvery-white, shiny metallic ore that contains a minute amount of uranium-234 (U-234).
  • Uranium mill tailings= naturally radioactive residue from the processing of uranium ore. Although the milling process recovers about 95% of the uranium, the residues, or tailings, contain several isotopes of naturally occurring radioactive material, including uranium (U), thorium (Th), radium (Ra), polonium (Po), and radon (Rn).
  • Urate= Salt of uric acid.
  • Uremia= Presence of excessive amounts of urea and nitrogen in the blood.
  • Urogram, urography= a radiograph/examination of the urinary tract, obtained using an iodinated contrast agent. For excretory urography, the contrast medium is injected intravenously; for retrograde urography it is instilled by direct retrograde flow through ureteral catheters.
  • Urologic unit= Specialized radiography equipment
  • Urticaria= a pruritic skin eruption, usually the result of an allergic reaction, characterized by transient wheals of varying shapes and sizes with well-defined erythematous margins and pale centers. Same as hives.
  • VA=Volt=ampere. Measure of apparent power in a reactive circuit found by multiplying the voltage by the current.
  • Vaccine, vaccination= a suspension of attenuated or killed microorganisms administered intradermally, intramuscularly, orally, or subcutaneously to induce active immunity to infectious disease.
  • Vaccine= Low dose of dead or deactivated bacteria or virus.
  • Vacuum= A space from which air has been removed.
  • Valence energy band= The outermost (sometimes the next-to-outermost) orbital shell.
  • Valence= The chemical combining characteristic of an element; determined by the number of electrons in the outermost shell.
  • Valgus deformity=Knee deformity in which the lateral side of the knee joint is narrower than the medial side.
  • Valid choice= a selection of options, all of which are acceptable. Offering valid choices to patients increases their sense of autonomy.
  • Valsalva maneuver= any forced expiratory effort against a closed airway, such as when an individual holds the breath and tightens the muscles in a concerted, strenuous effort to move a heavy object.
  • Value= a personal belief about the worth of a given idea or behavior.
  • Valvulae conniventes= Circular folds of the small bowel.
  • Variance=A numeric representation of the dispersion of data around the mean in a given sample.
  • Varus deformity=Knee deformity in which the medial side of the knee joint is narrower than the lateral side.
  • Vas deferens= Muscular tube that passes through the inguinal canal as part of the spermatic cord connecting the epididymis and seminal vesicle to form the ejaculatory duct.
  • Vascular lung markings=White markings in the lung fields that indicate blood vessels on a chest x-ray.
  • Vascular= pertaining to a blood vessel.
  • Vasculitis= Inflammation of a vessel.
  • Vasectomy= Severing of the vas deferens.
  • Vasoconstriction= a narrowing of the lumen of any blood vessel, especially the arterioles and the veins in the blood reservoirs of the skin and the abdominal viscera.
  • Vasodilation= an increase in the diameter of the blood vessels.
  • Vasovagal reflex= a stimulation of the vagus nerve by reflex in which irritation of the larynx, trachea, or rectum results in slowing of the pulse rate.
  • Vector (of infection)= an animal in whose body a pathogen multiplies or develops before becoming infective to a new host.
  • Vegetations= Abnormal growth of tissue around a heart valve.
  • Vehicle (of infection)= any substance, such as food or water, that can serve as a mode of transmission for infectious agents.
  • Veiling Glare=Glare caused by light being reflected from the window of the output phosphor in an image intensifier. Also known as flare.
  • Velocity of Propagation (VP)=The transmission speed of electrical energy in a length of cable compared to speed of light in free space. Usually expressed as a percentage.
  • Venipuncture= the transcutaneous puncture of a vein by a sharp, rigid needle with a stylet, by a cannula carrying a flexible plastic catheter, or by a steel needle attached to a syringe or catheter. Venipuncture provides access to a vein for medication or fluid administration or to draw blood for testing.
  • Venogram, venography= a radiographic image/study of the veins. Same as phlebogram.
  • Ventilation= the process by which gases are moved into and out of the lungs.
  • Ventilation=The process by which air is changed into and out of a specific area.
  • Ventilator= any of several devices used in respiratory therapy to provide assisted respiration and intensive positive-pressure breathing.
  • Ventral (ventro-)=See anterior.
  • Ventricle= small cavity, such as the right and the left ventricles of the heart or one of the cavities filled with cerebrospinal fluid in the brain.
  • Ventricular septal defect= Opening between the left and right ventricles allowing blood to flow back into the right ventricle instead of entering the systemic circulation.
  • Vermis= Structure resembling a worm.
  • Vertical Distance Measurement=A quality control test variable for ultrasound equipment measuring along the sound beam axis. Also known as depth calibration accuracy.
  • Vertigo= a sensation of instability, loss of equilibrium, or rotation, caused by a disturbance in the semicircular canal of the inner ear or the vestibular nuclei of the brainstem.
  • VHF=Very High Frequency. International Telecommunication Union designation for the 30=300 mhz band of frequencies.
  • Vial= a glass container with a metal-enclosed rubber seal.
  • Vidicon=A type of television camera tube.
  • Viewable area= measured from one corner of the display to the opposite corner diagonally.
  • Viewbox Illuminator=An electronic device for viewing transparency images such as radiographs.
  • Vignetting=A decrease in brightness toward the periphery of a fluoroscopic image when using an image intensifier tube.
  • Villi= Fingerlike projections of the small bowel to increase the inner surface area.
  • Viral meningitis= Inflammation of the meninges caused by virus.
  • Virion= a rudimentary virus particle with a central nucleoid surrounded by a protein sheath or capsid.
  • Virtue-based ethics= theory that places value on virtues and admirable character traits such as caring, faithfulness, trustworthiness, compassion, and courage.
  • Virulence factors= characteristics of certain microorganisms that cause them to be pathogenic and distinguish them from normal flora. These factors enable bacteria to destroy or damage host cells and resist destruction by the host’s cellular defenses.
  • Virus, viral= a minute parasitic microorganism much smaller than a bacterium that, having no independent metabolic activity, may replicate only within a cell of a living plant or animal host.
  • Virus= One of a group of minute infectious agents characterized by a lack of independent metabolism and by the ability to reproduce only within living host cells.
  • Viscosity, viscous= the ability or inability of a fluid solution to flow easily.
  • Viscous= Thick, sticky.
  • Viscus (plural, viscera), visceral= an internal organ, pertaining to an organ.
  • Viscus= Any large internal organ, especially in the abdomen.
  • Visual acuity= The ability of the eye to resolve detail.
  • Vitamins= Organic compounds essential for normal physiologic and metabolic function.
  • VLF=Very Low Frequency. International Telecommunications Union designation for the 3=30 khz band of frequencies.
  • Void= to empty, or evacuate, such as urine from the bladder.
  • Volt (V)= The unit of potential difference.
  • Volt, voltage= the unit of electrical potential. In an electric circuit a volt is the force required to send 1 ampere of current through 1 ohm of resistance, or the difference in potential between two points on a conductor carrying a charge of 1 ampere when there is a dissipation of 1 watt between them.
  • Volt=A unit of electromotive force.
  • Voltage (V)= The unit of potential difference.
  • Voltage Drop=The voltage developed across a component or conductor by the current flow through the resistance or impedance of the component or conductor.
  • Voltage Rating=The highest voltage that may be continuously applied to a cable construction in conformance with standards or specifications.
  • Voltage ripple= The net voltage produced during full-wave rectification.
  • Voltage Ripple=The variation from the peak voltage through the x-ray tube in an x-ray generator.
  • Voltage Standing Wave Ratio=Ratio of maximum voltage of the standing wave to the minimum voltage of the standing wave. See also Standing Wave Ratio.
  • Voltage=Electrical potential of electromotive force expressed in volts.
  • Voltmeter= A device used to measure current connected in parallel; measures potential difference in volts.
  • Volume of interest (VOI)=Brightness values (raw data) that represent only the anatomic structures of interest in digital radiography.
  • Volume replenishment= Type of replenishment system used for high-volume systems; activates when films enter the processor.
  • Volume Replenishment=A type of system in an automatic processor that replenishes a volume of solution for each film introduced.
  • Volume-rendered imaging= Technique that takes all the raw CT data density information and uses them to simulate three-dimensional images.
  • Voluntary motion=Motion that the patient is able to control.
  • Voxel= Three-dimensional volume correlating to each pixel. Washing The process of using water to remove as much of the fixer and developer solutions as possible.
  • VSWR=Voltage Standing Wave Ratio.
  • Water-soluble vitamins= Vitamins B and C, which cannot be stored and therefore must be included in the daily diet.
  • Watt=A unit of electrical power.
  • Wave Form=A graphical representation of a varying quantity. Usually, time is represented on the horizontal axis, and the current or voltage value is represented on the vertical axis.
  • Wavelength= The distance between two successive points on a wave.
  • Wavelength= with respect to a sine wave, the distance between a given point on one wave cycle and the corresponding point on the next successive wave cycle.
  • Wavelength=The distance between positive peaks of a signal. As the frequency increases, and waves get closer together, the wavelength decreases.
  • Web-based system= very similar to a client/server system with regard to how the data flow, but the biggest difference is that not only are the images held centrally but so is the application software for the client display.
  • Weber (Wb)= SI unit used to measure magnetic flux.
  • Wedge filter= A type of compensating filter used to even out densities such as in the foot or lower extremities.
  • Weight= The force that an object exerts under the influence of gravity.
  • Weight-bearing=Act of putting weight on the structure, as with a standing lateral foot or AP knee.
  • Weighting factor (WF)= an approximate measure of the relative biological effectiveness of a particular radiation compared with a reference radiation. The reference is 250 kev x-rays. The weighting factor is multiplied by the dose to determine the dose equivalent. Formerly termed quality factor (QF).
  • Weighting factor= A multiplier that is used for converting the equivalent dose to a specific organ or tissue into what is called the “effective dose.” The goal of this process was to develop a method for expressing the dose to a portion of the body in terms of an equivalent dose to the whole body that would carry with it an equivalent risk in terms of the associated fatal cancer probability. It applies only to the stochastic effects of radiation.
  • Wet imager= printer that uses chemicals to develop the film.
  • Whole-body count= the measure and analysis of the radiation being emitted from a person’s entire body, detected by a counter external to the body.
  • Whole-body exposure= an exposure of the body to radiation, in which the entire body, rather than an isolated part, is irradiated by an external source.
  • Wide area network (WAN)=  network that spans a large area, city, state, nation, continent, and/or world.
  • Wimberger’s sign of scurvy= Epiphyseal ossification centers are demineralized and surrounded by dense, sharply demarcated rings of calcification.
  • Window level= The digital processing that produces changes in density/brightness.
  • Window Level=A value in digital imaging that selects the level of the displayed band of values within the complete range.
  • Window Leveling=A manipulation of the dynamic range, allowing for the selection of more or less shades of gray to enhance image contrast.
  • Window width= The digital processing that produces changes in the range of density/brightness, which can be used to control contrast.
  • Window Width=A value in digital imaging that selects the width of the band of values in the digital signal that can be represented as gray tones in the image.
  • Window= A structure where the primary x-ray beams exits the envelope, which allows less absorption or scatter of photons.
  • Window= image manipulation parameter that changes screen image brightness usually through the use of a mouse.
  • Windowing=1. In digital radiography, postprocessing manipulation feature whereby the technologist adjusts image contrast and density. 2. Postprocessing manipulation of the image’s brightness and contrast to demonstrate an area of interest better.
  • Wireless= network communication medium that uses either infrared or radio frequencies as its means of communication.
  • Wiring= The parts within the cathode assembly.
  • Workflow= amount of work or examinations completed over a period of time.
  • X-ray quality= A measurement of the penetrating ability of the x-ray beam.
  • X-ray quantity= A measure of the number of x-ray photons in the useful beam.
  • X-ray= electromagnetic radiation caused by deflection of electrons from their original paths, or inner orbital electrons that change their orbital levels around the atomic nucleus. X-rays, like gamma rays can travel long distances through air and most other materials. Like gamma rays, x-rays require more shielding to reduce their intensity than do beta or alpha particles. X-rays and gamma rays differ primarily in their origin= x-rays originate in the electronic shell; gamma rays originate in the nucleus.
  • Yeast= any unicellular, usually oval, nucleated fungus that reproduces by budding.
  • Z number= The number of nuclear protons in an atom, unique to each element; also known as the atomic number.
  • Zenker’s diverticula= Outpouching that arises from the posterior wall of the upper esophagus.
  • Zero potential= A neutral reference point for discussing charges. The earth is defined as zero; also known as ground potential.
  • Zonography= Narrow-angle tomography.

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    HIMSS 2014: The Challenge of Image Sharing

    February 5, 2014 by Carestream Health

    Greg Freiherr

    Before LAN there was sneakernet. Highly reliable but time-consuming, sneakernet transfers data the old fashioned way via CD, DVD, floppy disk or USB-drive walked from one computer to another. It has lasting appeal. Obviously. Consider the range. Flash drives holding from 4 to 512 MB can look like just about anything: minions…surgeons…thumbs. (Gotta love ‘em.)

    It shouldn’t be surprising, therefore, that patients are carrying their CTs, MRIs and other medical images from one doctor to another. They might be shared over networks, but these are uncommon, their implementation restricted by provider cost concerns and patient privacy issues.

    Having a simple way to share medical images across providers and between far flung locations has obvious benefits for everyone. The sheer volume of data and the importance of images to patient management underscore this. And this will only grow. Radiology is evolving, its role expanding from diagnostic to therapeutic assessment, screening to patient follow-up. Little wonder, then, that an efficient means to transfer images among providers has enormous potential to impact the quality and cost of care.

    This shouldn’t even be an issue. For most of the past decade, medicine has been working toward regional health information organizations (RHIOs) and health information exchanges (HIEs) to enable the sharing of medical information. Yet these have fallen short. Even the most successful only share summaries, leaving the transfer of actual data to private solutions.

    The most promising of these solutions leave no footprint. They are compatible with multiple operating systems and browsers; run on mobile devices – smartphones, tablets and other computing “surfaces;” and draw data from telecom networks being built out to handle YouTube, Netflix and Instagram. Whether they should replace shoe leather goes without saying.

    While easy and seemingly inexpensive, sneakernet is resource intensive for both patient and provider. The patient must obtain the images from where they were generated, transport them, and then hope that the receiving facility can read the discs. Images are valueless, if they cannot be read by the referred institution, an uncertainty amplified by the number of facilities to which the patient is referred as the time between facilities raises the risk of losing or damaging the storage media.

    As we approach another HIMSS, sneakernets clearly have run their course. Image transfer through RHIOs or IHEs is beyond reach. Zero footprint technologies are at hand, but not widely applied. Their adoption depends on demonstrating the degree to which they can efficiently exchange data, and whether their use can help increase revenue and control costs.

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