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Take 9: Dose Limits & Exposure Patterns

For the protection and safety of radiation workers ands staff, it is very important to limit the amount of dose as much as possible.   It is our responsibility as radiation workers to keep radiation exposure ALARA- As Low As Reasonably Achievable!  In addition to the three keys (time, distance, and shielding) of radiation safety and protection, there are other ways to manage dose.  For example, the number of image taken and repeated.  During fluoroscopy, setting the number of frames per second is one way the radiologist can limit patient dose.  The more frames (or pictures) taken per second, the more radiation being exposed to the patient and surrounding people (ASRT, 2010).  In order to effectively protect workers and patients, dose limits have been established.  Check out the table below!... sorry for the poor quality screenshot.  Note: Dose equivalent is measured in Sieverts and/ or rems. (1 rem= .01 Sv) 
Statkiewicz-Sherer, Mary Alice, Paula J. Visconti, E. Russell Ritenour, and Kelli Haynes. Radiation Protection in Medical Radiography. Maryland Heights, MO: Elsevier/Mosby, 2014. Print.




Additionally in "Take 8," I had mentioned that when we weren't assisting the radiologist, we'd either stand directly behind the radiologist a few feet back or behind the leaded wall.  The reason why we wouldn't hang out near the patients head or feet is because the radiation exposure is greatest at those ends.  What's interesting is that radiation pattern resembles a figure 8.  This pattern demonstrates that the exposure is greatest at the head and foot end of the patient table and is least in the center.  

Bontrager, Kenneth L., and John P. Lampignano. Bontragers handbook of radiographic positioning and techniques / Kenneth L. Bontrager, MA, John P. Lampignamo, MEd. St. Louis, MO: Elsevier Mosby, 2014. Print.


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