Answer to Question #10525 Submitted to "Ask the Experts"

Category: Medical and Dental Patient Issues — Diagnostic X Ray and CT

The following question was answered by an expert in the appropriate field:

I am an orthopedic surgeon in France who frequently uses a C-arm fluoroscope during surgical. (And most of the time I wear a protective lead vest and skirt.) An incident occurred and I am worried. During surgery I took a few views and then continued with the surgery. Because of the shoes we wear and the surgical drapes over the pedal, I did not realize I was accidentally stepping on the pedal that activates the C-arm. After a few seconds, a nurse informed us and I took my foot off the pedal. Is there a maximum allowed exposure for the C-arm or does the radiation keep coming as long as one presses the pedal? Would you suspect the described amount of exposure is worrisome since my head was right next to C-arm?
It is doubtful that you received a significant radiation exposure. You say that the C-arm was generating x rays for “a few seconds” longer than intended. Even if it were a few minutes, your exposure would be minimal. Consider this for perspective: cardiologists performing both diagnostic and interventional fluoroscopic procedures, and radiologists performing interventional procedures routinely have fluoroscopic on-times that are many minutes (20–90 minutes with occasional cases even higher) without exceeding dose limits. 

The United States standards for C-arm equipment (and I assume France has similar requirements) include limiting the x-ray beam to the size of the image receptor (image intensifier). Therefore, your head would not have been exposed to direct radiation unless you had it between the tube and the image intensifier. Your hands, however, might have been in the primary beam. But, even then, the patient was probably between your hands and the x-ray tube. Which brings me to another point—the patient was the most exposed individual in the operating room. 

You also asked whether there is a maximum allowed exposure for the C-arm. I am not sure if you are asking about regulations or equipment limitations. There may be a duty cycle limit to the equipment, but it would be much longer than a few seconds. In the United States, C-arm fluoroscopes must have an audible alarm which goes off after every five minutes of cumulative fluoroscopic exposure. The alarm can be reset any number of times. It is up to the physician to make sure that the dose to the patient does no harm.

Finally, I have three suggestions: (1) ALWAYS wear protective garments when operating the C-arm, (2) check for availability of personal radiation monitors at your facility and if available wear them, and (3) look for a visual indicator (e.g., an x ray on light) that is activated when x rays are being generated.

Kent Lambert, CHP
Answer posted on 30 January 2013. The information posted on this web page is intended as general reference information only. Specific facts and circumstances may affect the applicability of concepts, materials, and information described herein. The information provided is not a substitute for professional advice and should not be relied upon in the absence of such professional advice. To the best of our knowledge, answers are correct at the time they are posted. Be advised that over time, requirements could change, new data could be made available, and Internet links could change, affecting the correctness of the answers. Answers are the professional opinions of the expert responding to each question; they do not necessarily represent the position of the Health Physics Society.