The dramatic paradigm shift in vascular surgery in the last decade and a half, resulting in the increased and widespread application of catheter-based fluoroscopic interventions makes the topic of radiation injury timely for all of us. This report is a follow up of a study by the same group published in the Journal of Vascular Surgery in 2013 (58:715-21) in which they demonstrated that the use of a variety of radiation safety measures including increasing table height, utilizing collimation and angulation, decreasing magnification modes, and maintaining minimal patient-to-detector distance resulted in a 60% reduction in skin dose to their patients when measured as an index of peak skin dose to reference air kerma (PSD/RAK). Unfortunately, skin exposure remained high for FEVAR despite these measures, underscoring the fact that for very complex interventions, even with excellent radiation safety practices, the risk of skin injury remains a reality.
The fact that skin doses as high as 11 Gy did not result in any deterministic injuries is both reassuring and a little surprising. According to the Centers for Disease Control and Prevention, radiation doses of greater than 2 Gy but less than 15 Gy will usually result in erythema within 1-2 days, with a second period of erythema and edema at 2-5 weeks, occasionally resulting in desquamation at 6-7 weeks. Late changes can include mild skin atrophy and some hyperpigmentation. Although complete healing can usually be expected at these doses, squamous skin cancer can still occur, often more than a decade after exposure.
So why were no injuries seen? It may be that some were missed since follow-up examinations were not performed in 100% of their patients at any time interval, and it’s not stated whether exams were routinely performed in the first 1-2 days, when I would presume most patients were still hospitalized and the first stage of skin erythema is usually seen. Alternatively, it may be that the surrogate measure of either RAK or the index of PSD/RAK overestimated the true radiation skin dose, which seems highly likely, especially if the time of exposure in any one location was based less on the frequent changes in gantry angle and table position so commonly used in these procedures.
In our hospital, the Massachusetts Department of Public Health regulations require the patient and their physician be notified by letter when the estimated total absorbed radiation dose equals or exceeds 2 Gy. This is based on calculations by our physicist who reviews the details of any case in which the RAK measured equals or exceeds 2 Gy. Like the experiences of the authors, this most commonly occurs with lengthy and complex interventions. In our experience, we have never observed a significant skin injury presumably for the same reason – the exposure in any one location tends to be far less than the total calculated skin dose. Nevertheless, this study should not lull surgeons into a sense of complacency regarding the risk to the patient (and themselves and their staff). As our comfort and expertise with complex interventions increases, it is likely that radiation exposure will continue to increase, placing our patients at increased risk. Understanding the risk of radiation skin injury and how to minimize it is critical for any surgeon performing FEVAR and any other complex intervention utilizing fluoroscopic imaging.
Dr. Frank Pomposelli is an associate professor of surgery at Harvard Medical School; clinical chief, division of vascular surgery at the Beth Israel Deaconess Medical Center; and section chief, division of vascular surgery, New England Baptist Hospital, Boston. He is also an associate medical editor for Vascular Specialist.
