Radiation scatter from orthopedic hardware can harm first assistants' eyes during mini-C arm fluoroscopy. Surgeons and first assistants should use the mini-C arm in the vertical position as much as possible while wearing lead-lined glasses and other protective clothing, Michael Groover, DO, told Medscape Medical News.
Here are seven things to know.
1. The research was presented at the American Academy of Orthopaedic Surgeons 2018 Annual Meeting in New Orleans.
2. Orthopedic surgeons often use the mini-C arm fluoroscopy when implanting metal devices such as plates and retractors, and previous studies that have measured radiation exposure from these procedures have generally determined the exposure to be at safe levels. Few studies, however, have considered the way metal hardware scatters the X-rays, according to Dr. Groover.
3. Dr. Groover and his colleagues positioned an InSight 2 mini-C arm over a hand table set up to fix forearm or wrist fracturers to determine if metal poses an increased risk of radiation exposure. Parallel plate radiation detectors measured the radiation at each person's eyes, thyroid gland, chest, gonads, and the hands of the person in the surgeon's position. A leg of lamb lay in the X-ray beam's center.
4. The researches measured radiation with the mini-C arm in the horizontal position, first without any hardware in the lamb leg and then with a 3.5 millimeter stainless steel plate and six cortical screws in the lamb's leg. They repeated this with the mini-C arm in the vertical position.
5. Exposure to the first assistant's eyes exceeded the annual 2000 mrem recommended by the International Commission on Radiological Protection. In the vertical position, however, the radiation exposure to the first assistants' eyes was only a fraction of the horizontal position exposure. According to Dr. Groover, the horizontal position is commonly used because it is convenient for limb positioning.
6. According to Robert Orfaly, MD, orthopedic surgeons are using more fluoroscopy than in the past, partly because of the growth of procedures that use smaller incisions. Dr. Orfaly stressed the importance of wearing lead-lined glasses, but most hospitals do not provide the protective gear. They are also heavy, distort vision and must be specially made if the user wears prescription lenses.
7. Dr. Orfaly suggested using a targeting system to help position hardware without continuous imaging to reduce exposure from mini-C arms.
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