Quality Assurance And Quality Control in Radiography

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Quality Management

Quality Assurance And Quality Control

Goals of Quality Assurance Progra

“…to ensure accurate and timely diagnosis and treatment at the minimum dose to the patient and staff.”

-“Information obtained from X-ray equipment must be of utmost quality to ensure accurate diagnosis and treatment.”

-“The consequence of poor quality diagnostic information may be incorrect diagnosis resulting in repeat radiographic procedures, unnecessary radiation doses to the patient, delayed or improper patient treatment and increased cost.” (SC35 P. 38)

Costs of QA Program

1.Personnel – staff required to perform tests and record results

2.Test equipment – phantoms and other specific equipment will need to be purchased (see #4)

3.Test images – 2 to 5% of films used by a facility for sensitometry, phantom imaging, and equipment testing

4.External organizations – facilities may choose to have an external organization do all QC testing

Benefits of QA Program

1.Film and processing chemicals – a decrease in the number of retakes = a reduction in the number of films and processing chemicals used

2.Equipment – reduction in retakes = less wear and tear on equipment also problems detected early are generally less costly to repair

3.Patient flow – reduction in repeats coupled with better image quality will allow for efficient use of time and greater patient throughput

 

Implementation of QA Program

1.Policies and guidelines development i.Radiology personnel

ii.Policies for minimizing radiation exposure to x-ray operators and staff

iii.Policies for minimizing radiation exposure to patients

iv.Guidelines for equipment quality control testing

v.Policies for acquisition of new x-ray imaging equipment

vi.Policy for record keeping

2.Establishment of quality control procedures

 i.Equipment operation

-Films and processing must meet manufacturers’ speed and contrast values

-CR and DR imaging systems must be properly calibrated with the x-ray systems

ii.Baseline performance

-Baseline values must be established when the equipment is operating properly; these values will be used to diagnose any changes in equipment performance

iii.Reference test image

-Made by using the x-ray equipment, image processing system and quality control phantom and will be used for comparison of other quality control test images

vi..Result evaluation and action levels ———-Determination of acceptable or unacceptable limits of equipment operation along with a list of corrective actions that may be required

 

Establishment of Administrative Procedures 1.Responsibility

-Level of responsibilities and involvement of the owner and staff must be clearly identified, communicated and understood

2.Record keeping

-Clear documentation of information gathered and readily available for evaluation

3.Evaluation of data

-Recorded data should be evaluated immediately and necessary action taken

4. Limits of acceptability of data

-Upper and lower limits of acceptability must be determined and documented; when limits are reached corrective actions must be taken

5.Testing frequency

A balance must be reached between cost of testing, disruption to the operation of the facility and maintenance of quality

6.Corrective actions

-A decision tree system should be developed to provide guidance when equipment performance deviates beyond the set limits

 

Monitoring Equipment Performance

Quality Control Testing

-Method to monitor and evaluate equipment to ensure it is functioning within normal parameters

-System needs to be in place to ensure scheduled testing is performed, results evaluated, and if necessary corrective actions taken to ensure compliance with manufacturer or Safety Code recommendations

Daily Quality Control Tests

1.Darkroom cleanliness (SC35: P. 44 D5)

-All working surfaces and floors should be cleaned daily

-Dust and debris may be seen using a UV-B lamp

2.Film processor function (SC35: P. 44 D6)

*Should be evaluated every morning before performing clinical examinations

-Film processor solution levels

-Displayed processor temperature

* Sensitometric strip

-B+F must be within +0.05 of established operating level

-Mid-density range (speed) must be within ± 0.15 of the established operating level

-Density difference (contrast) must be within ± 0.15 of the established operating level

 

Weekly Quality Control Tests

1.Visual inspection of cleanliness of imaging systems (SC35: P. 45 W1)

-Dust and dirt minimized in image reception area

2.Viewboxes condition (SC35: P. 45 W2)

-Inspected visually for cleanliness, viewing area discolouration, and improper illumination

Monthly Quality Control Tests

1.Cassettes and screen cleaning (SC35: P. 47 M1)

*Intensifying screens

-Inspected for damage

-Cleaned with manufacturer recommended cleaner

-Inspection for dust particles should be done with an ultraviolet light

*Cassettes Checked for cleanliness, wear, warping, fatigue of foam compression material, closure mechanism, and light leaks

2.Darkroom temperature and humidity conditions (SC35: P. 47 M2) .

*Temperature should be between 18°C and 23°C

*Humidity between 40% and 60%

3.Darkroom light conditions (SC35: P. 47 M3) *Assessment done after a 10 to 15 minute adaptation period to dark conditions (safelight turned off)

-Attention paid to door seal and mounting area around the processor

4.Film processor operation (SC35: P. 47 M4) *Accuracy of processor display

-Checked with a non-mercury thermometer

-Developer temperature should be accurate to within 0.5°C

*Replenishment rate compared with manufacturers recommended baseline levels

*All processing solutions should be changed and processor solution tanks cleaned

*Fixer retention test to ensure fixer is adequately removed from processed films

5.Retake analysis (SC35: P. 47 M5)

-Record of every retake including reason for retake along with any corrective action

-Analysis on retake records to identify and correct trends or repeated errors

-Retake rate should be less than 5%, not including quality control films

-If images contain diagnostic patient information, they should be maintained in the patient file

 

Annual Quality Control Tests

1.Safelight test (SC35: P. 51 Y1)

-Film strip exposed to an optical density of 1.2 must not show an increase in optical density > 0.05 in two minutes exposure in darkroom light environment

2.Screen/Film contact (SC35: P. 51 Y2)

-All cassettes must be tested

-Large areas of poor contact that remain in the same location on subsequent test should be replaced

3.Viewboxes (SC35: P. 55 Y26)

*All viewboxes must be tested for the following

-Luminance should be at least 2,500 nits (cd/m2)

-Light output uniformity measurements should be within 10%

-Light output homogeneity between a bank of viewboxes should be uniform (within 20% of mean)

-Ambient light control in the reading room must be less than 50 lux (5-10 lux recommended)

 

Ancillary Equipment

*Cassette Cleaning and Inspection

-SC35 recommendations were indicated on slide “Monitoring Equipment Performance P.5”

-Care of intensifying screens and cassettes were also discussed in Part 1: Unit 7 “Care”

*Film/Screen Contact

-Film/screen contact was discussed in Part 1: Unit 7 “Care”

-Recorded detail is also affected by film/screen contact therefore further information is available in Part 2: Unit 4 “Factors Affecting Recorded Detail”

*Viewbox Uniformity

SC35 recommendations were indicated on slide “Monitoring Equipment Performance P.10”

*Digital Radiography Detector Systems and Display Monitors are outside of the scope of this course.

Retake Analysis

*Provides important data about equipment, departmental procedures, and skill level of technical staff

*Knowledge acquired from retake analysis will facilitate solutions to minimize the need to re-expose patients

*Advantages of lower retake rates

-Improved department efficiency

>The amount of time required to complete a diagnostic procedure decreases; this increases patient satisfaction and allows the department to service more patients

-Lower department costs

>Cost of film, processing, labour, and depreciation of equipment all decrease

-Lower patient doses

>A repeat exposure will double the dose to the patient

 

 

*Casual Retake Rate

-Rejected films are sorted according to established categories and recorded

-Most departments tabulate data monthly (SC35 recommendation)

-The casual retake rate is the percentage of retakes from a specific cause (i.e. under exposed)

No. of retakes in category X 100%

———————————————

No. of total retake films

Total Retake Rate

*Many factors influence the total retake rate -Quality of equipment

-Competence of technical staff

-The patient population

-Number of images accepted by radiologists to diagnose

No. of retake films X 100%

————————————-

No. of total films produced

Outcome of Retake Analysis

-Data is used to identify the major factor(s) contributing to the overall retake rate

*If certain equipment is identified, the department now has justification for repairs or replacement costs

*If certain positions (AP open mouth) are abnormally high, additional in-service education or other corrective action may alleviate the problem

Acceptable Limits

-Retake rate should be 4 – 6 % (Papp)

-SC-35 indicates rate should be < 5%

 

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