Radiation Skin Injury: More Frequent After Complex Endovascular Procedures?
Melissa L Kirkwood, Gary M Arbique, Jeffery B Guild, Carlos Timaran, Jayer Chung, Gregory Modrall, Jon A Anderson, R James Valentine
UT Southwestern Medical Center, Dallas, TX
Background: The risk of deterministic skin injury is determined by the dose of ionizing radiation in any given procedure. Transient erythema occurs at doses of 2-5 Gy, while permanent epilation, ulceration and desquamation are expected at doses above this level. Complex endovascular procedures (CEP) such as fenestrated endovascular aortic stent grafts (FEVAR) are associated with high radiation doses. Although CEP cases are being performed with increasing frequency, the risk of associated skin injury has not been examined. We hypothesized that skin injury following these exposures is likely under recognized and under reported. This study examined the frequency and severity of deterministic effects and evaluated patient characteristics that might predispose to radiation injury in CEP
Methods: CEP was defined as a procedure with a radiation dose > 5 Gy (NCRP threshold for substantial radiation dose level[SRDL]). Radiation dose and operating factors were recorded for all CEP performed in a hybrid room over a 30 month period. Patient medical records were retrospectively reviewed for evidence of skin injury. Patients were seen in follow up daily until discharge and then at weeks 2, 6, months 3, 6 and one year. Phone interviews were conducted to determine the presence of any skin related complaints, including erythema, epilation, and necrosis. Peak Skin dose (PSD) distributions were calculated for FEVARs using custom software employing input data from fluoroscopic machine logs. These calculations were validated against gafchromic film measurements. The effects of patient factors and procedural skin dose on cutaneous skin injury were analyzed for statistical significance. Dose was summed for the subset of patients with multiple procedures within 6 months of the SRDL event, consistent with Joint Commission recommendations.
Results: 61 CEP reached a RAK of 5 Gy. There were 50 FEVARs, 6 embolizations, 1 TEVAR, 1 EVAR, 1 carotid, and 2 visceral interventions. The patient cohort was 79% male and had a mean BMI of 31. The average RAK was 8 +/- 2 Gy (5.0 —15.9 Gy). 16 patients had multiple CEPs within 6 months of the SRDL event, with a mean cumulative RAK of 12 +/- 3 Gy (7.0 - 18.4 Gy) for this patient subset. The mean FEVAR PSD was 6.8 +/- 3.4 Gy (3.7- 17.8 Gy), with a mean PSD/ RAK ratio of 0.67+/- 0.12. Three patients were lost to follow up before their first post- operative visit. Patients were seen at 2 weeks (95%), 6 weeks (88%), 3 months (84%), 6 months (73%) and 1 year (79%) following the SRDL event. No radiation skin injuries were found. Two patients had skin complaints unrelated to radiation, a HSV culture positive focal outbreak of shingles two weeks following the procedure and a diffuse desquamating, erythematous drug reaction.
Conclusion: Radiation doses in this study exceeded published thresholds for cutaneous injury, yet no radiation skin injuries were observed. This data suggests that other variables besides radiation dose may play a role in deterministic injuries. Nonetheless, deterministic skin injuries
may be less frequent than previously reported, and the risk is not increased in complex endovascular procedures.
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