K-edge & K shell

Posted on Updated on

K-edge describes a sudden increase in the attenuation coefficient of photons occurring at a photon energy just above the binding energy of the K shell electron of the atoms interacting with the photons. The sudden increase in attenuation is due to photoelectric absorption of the photons. For this interaction to occur, the photons must have more energy than the binding energy of the K shell electrons. A photon having an energy just above the binding energy of the electron is therefore more likely to be absorbed than a photon having an energy just below this binding energy.


The two X-ray contrast media iodine and barium have ideal K shell binding energies for absorption of X-rays, 33.2 keV and 37.4 keV, respectively, which is close to the mean energy of most diagnostic X-ray beams. Similar sudden increases in attenuation may also be found for other inner shells than the K shell; the general term for the phenomenon is absorption edge.


19 thoughts on “K-edge & K shell

    xxx said:
    September 5, 2016 at 7:03 am

    Justo aquí es el sitio adecuado para todo aquel que quiera entender este
    tema. Uno se da cuenta tanto sus casi difícil de discutir con usted (no es que yo personalmente me gustaría … jaja).
    No cabe duda de poner un nuevo giro a un tema que ha sido discutido durante
    mucho tiempo. Excelente material, simplemente genial!

    financial association said:
    August 14, 2014 at 7:09 am

    Looking forward to reading more. Great article. Really Great.
    financial association

    viajar en el tiempo said:
    August 11, 2014 at 9:48 am

    Im thankful for the blog article.Much thanks again. Will read on…
    libros en lГ­nea

    structural engineer columbia sc said:
    August 9, 2014 at 7:25 am

    Appreciate you sharing, great blog.
    forensic engineer columbia sc

    Affiliate Cash Craze Review said:
    August 8, 2014 at 5:51 am

    Very neat article.Really thank you! Great.
    Affiliate Cash Craze Review

    Bucuresti said:
    August 7, 2014 at 1:45 pm

    Very neat blog article.Much thanks again. Fantastic.

    annuaire federation sophrologie coaching said:
    August 7, 2014 at 6:56 am

    Very neat blog article.Much thanks again. Want more.
    annuaire federation sophrologie coaching

    nju mobile opinie said:
    August 7, 2014 at 4:56 am

    Awesome post.Much thanks again. Much obliged.
    siec telefoni nju mobile

    high security locks said:
    August 6, 2014 at 3:54 am

    Hey, thanks for the post.Really looking forward to read more. Cool.
    high security locks

    mqadjhcbl@gmail.com said:
    August 5, 2014 at 1:54 pm

    Wow! It’s a fastidious jQuery script; I was also searching for that, so i got it right now from at this place. Keep it up admin.
    click here http://4lifeinsurancequotes.com/

    baja said:
    August 5, 2014 at 6:26 am

    A round of applause for your blog post.Thanks Again. Keep writing.

    Amusement Parks Hotels said:
    August 4, 2014 at 3:05 am

    Really enjoyed this post.Really thank you! Great.
    Convention Centers Hotels

    web manager said:
    August 1, 2014 at 11:12 am

    Thanks-a-mundo for the article post.Much thanks again. Cool.
    website manager

    best 7 inch tablet said:
    July 30, 2014 at 8:43 pm

    I appreciate you sharing this article post.Thanks Again. Really Cool.
    best tablets 2013

    best tablets on the market said:
    July 30, 2014 at 5:04 pm

    I think this is a real great blog article. Want more.
    best 10 inch tablet

    fiverrr23Jz said:
    June 25, 2014 at 4:05 pm

    Awesome post.Really thank you!

    Dewayne Umbenhauer said:
    February 12, 2014 at 8:32 pm

    David, you do not receive copies of the previous letters. As the letters go forward that number may be in the hundreds. But if there’s a particular letter send us an email and maybe we can figure something out.

    December 3, 2011 at 2:58 pm

    Patient protection. It is the responsibility of the x-ray technician to useall available protective measures to reduce exposure to the patient. Only thoseradiographs requested by the dental officer will be taken. Be sure that a good qualityx-ray is produced each time a request is made. Wrong exposures, improper exposures,and faulty processing techniques must be avoided. These mistakes result in retakesand unnecessary patient exposure. Also, the lead apron must be used for everyexposure.
    NOTE:Lead aprons are stored flat or hung unfolded. Do not fold or bend lead apronsThese safety devices significantly reduce patient exposure.
    ALARA. ALARA stands for “as low as reasonably achievable.” It refersto taking every reasonable effort to maintain exposures to radiation as far belowprevailing dose limits as practical.
    1-11. X-RAY BEAM QUANTITY AND QUALITYThe quality of the x-ray beam is controlled by the voltage while the milliamperescontrol the quantity. An increase in the voltage and milliamperes reduces exposuretime for the patient.
    a. X-ray Beam Quality. The quality of the x-ray beam is controlled by theamount of voltage. Voltage provides contrast to the film. The desired contrast appearsas various shades of gray, black, and white in the x-ray negative (radiograph).Increased voltage provides less contrast (or more shades of gray). However, the beamhas more penetrating power. Decreased voltage, on the other hand, provides morecontrast (fewer shades of gray and more black and white shades). However, there isless penetrating power in the low voltage exposure. The technique most commonlyused to expose periapical and bite-wing X-rays is a 75 kilovolt peak and 15milliamperes.
    b. X-ray Beam Quantity. The x-ray beam quantity is controlled by themilliamperes. The more x-rays (photons) in the x-ray beam, the more dense (dark) thex-ray negative (radiograph) becomes. By increasing the milliamperes, we increase thenumber of available electrons at the cathode filament. When electrical current (voltage)is applied to the x-ray tube, the electrons cross the gap. When they impact on theanode (tungsten target), a greater number of x-rays (photons) are also produced. Themore x-rays that are available to penetrate an object, the more dense (dark) is the x-raynegative (radiograph).

    Heterogeneous clinical databases can assist clinical association awareness said:
    November 30, 2011 at 7:02 pm

    Researchers from Columbia University determined that, if examined properly, information contained in large, heterogeneous clinical databases can provide detailed illustrations of the temporal patterns of clinical associations and of the types of clinical associations that are made.

    The study, the results of which were published Nov. 28 in the Journal of the American Medical Informatics Association, builds off of past research regarding the relationships among clinical variables with a slightly different angle in comparison: the exploitation of time.

    Using the New York-Presbyterian Hospitals’ clinical database, which contains 22 years worth of EHR data on 3 million patients, the researchers calculated linear correlation between seven clinical laboratory values and 30 clinical concepts that included diseases, medications and symptoms.

    “A relatively simple method, which we use in this study, is to measure linear correlation between co-occurrences of pairs of variables, lagging one variable with respect to the other to assess the change in correlation as variables are shifted in time,” George Hripcsak, MD, of Columbia University, New York City, and his fellow researchers wrote.

    The study’s goal was to show that clinical databases can be used to reveal temporal associations, show different types of associations and determine any value associated with the exploitation of time.

    The study’s authors believe that large clinical databases will prove to be useful tools in the future because the aggregate data that they provide offer reflections of the healthcare process and the recording process, but that healthcare professionals must develop an understanding of EHRs’ inherent biases when conducting analyses of data.

    “We classified associations into three types — definitional, physiologic, and intentional — and showed that care must be taken in interpreting the associations because the health record represents the clinical workflow and not just patient physiology,” Hripcsak concluded. “We found that fully exploiting time in the record revealed the most detailed and reliable information.“

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )


Connecting to %s