The effectiveness of a free-standing lead-shield in reducing spine surgeon radiation exposure during intraoperative 3-dimensional imaging

Abstract

BACKGROUNDCONTEXT Intraoperative three-dimensional (3D) computed tomography (CT) imaging has become increasingly popular in spine surgery. Previous spine surgeon radiation exposure research has focused largely on procedures using fluoroscopy, however, few studies have been performed on the subject since the introduction of the 3D imaging systems. As a result, concerns have re-emerged over surgeon radiation exposure and the effectiveness of operating room (OR) protocols for decreasing workplace radiation. Current radiation safety guidelines require surgeons wear full body protective lead while any type of radiation is being administered during surgery. As a result, local institutions do not allow for the use of free-standing lead shields for sole radiation protection in the operating room. However, there is no data available to demonstrate whether the additional personal lead is required, or if in fact the lead shield alone is sufficient. PURPOSEThis study investigated the effectiveness of a free-standing lead shield in reducing spine surgeon radiation exposure in the operating room during intraoperative imaging. STUDY DESIGN/SETTINGA prospective clinical research study at a large, tertiary care center. PATIENT SAMPLETwenty-seven patients undergoing instrumented spinal procedures between June and August 2019. OUTCOME MEASURESFluoroscopy time, total fluoroscopy dose delivered, 3D dose delivered, total 3D spins, number of HD spins, number of standard spins, number of fluoroscopic images, number of spine levels operated on, patient size setting, shield distance from patient, radiation dose in front of shield, radiation dose behind shield. METHODSTwenty-seven instrumented spinal procedures using the O-Arm Imaging System (Medtronic, Minneapolis, MN) were observed to determine radiation exposure to a spine surgeon standing behind a lead shield in the OR. Two thermoluminescent dosimeters were used to measure scatter radiation in front of and behind lead shields. Both fluoroscopy and intraoperative CT based radiation exposure was recorded. The dosimeter readings were compared to determine the degree of radiation attenuation by the lead shield. Regression analysis of the exposure values from behind the shield, shield distance from the patient, and radiation dose delivered by the imaging system was utilized to estimate the number of cases required to surpass annual exposure limits. Case numbers were calculated for the highest “worst case” and “average case” exposure values. The safe annual occupation exposure limit determined by the National Council on Radiation Protection is five roentgen equivalent man (rem) or 50,000 microsieverts (μSv). RESULTSAverage surgeon radiation exposure per case was 0.694 μSv (SD: 0.501, Range: 0.105–2.167) behind the lead shield compared to 14.577 μSv (SD: 9.864, Range: 2.185–44.492) in front of the lead shield. The average radiation dose reduction by the lead shield was 13.962 μSv (SD: 9.49, Range: 2.08–42.72) per case, which is equivalent to an average of 95.65% (SD: 1.71) radiation attenuation by lead shielding. If surgeons stand behind lead shields in the OR, the annual number of 3D image-guided spinal procedures required to surpass exposure limits is 15,479 and 67,060 based on “worst case” and “average case” analyses, respectively. CONCLUSIONSOur study demonstrates standing behind intraoperative lead shields is very effective at decreasing radiation exposure to surgeons. Additionally, surgeon radiation doses behind lead shielding fall far below annual exposure limits. Surgeons should not need additional protective equipment when a lead shield is used.