S0926 The Impact of Replacing Old C-Arms on Radiation Exposure

Abstract

INTRODUCTION: Fluoroscopy guidance is widely employed in the field of gastroenterology, particularly by advanced endoscopists for ERCP. This comes with the risk of ionizing radiation. Ionization can cause DNA damage and cell death, leading to cancer and genetic defects. The longer the radiation exposure and the higher the radiation levels, the more likely one is to experience these consequences. Thus, the Nuclear Regulatory Commission (NRC) set an occupational dose limit of 50 Millisievert (mSv) effective dose per year. This study investigates the effect that updating our C-Arm will have on radiation exposure by comparing ionizing radiation effects of the OEC 9900 Elite to the newer OEC Elite. METHODS: We replicated the room positioning of a typical ERCP with a C-Arm adjacent to our bed and a stack of acrylic plates to simulate patient tissue. We measured energy output and levels of radiation in the air at bedside, 33” from the center of the bed (position of endoscopist), and at the head of the table, 46” from the center of the bed (position of anesthetist). The same set-up and measurements were completed with the OEC 9900 Elite and the OEC Elite. For each system and position we calculated mSv/hr with continuous and pulsed fluoroscopy. RESULTS: At each position, the OEC Elite emitted less energy and ionizing radiation or potential for radiation-induced harm than the OEC 9900 Elite. Continuous imaging with OEC 9900 Elite emitted 0.12 mSv/hr at the head of the bed and 0.49 mSv/hr at the bedside, while the OEC Elite emitted 0.04 mSv/hr and 0.14 mSv/hr, respectively. CONCLUSION: This study confirms that the greater the distance a staff member stands from the location that x-rays enter the patient, the lower their radiation exposure will be. Similarly, pulsed imaging mode lowers scatter radiation exposure. Unique to this study, is the demonstration that the OEC Elite operated at a lower energy output (kVp and mA), which resulted in lower scatter radiation exposure. With an average of 8 minutes of fluoroscopy time per ERCP and approximately 850 ERCP cases done annually in our endoscopy center, the annual effective dose is strongly influenced by C-Arm choice. Continuous fluoroscopy imaging with OEC 9900 Elite produces 13.92 mSv/year at the head of the bed and 55.60 mSv/year at the bedside. However, the OEC Elite produces 4.18 mSv/year and 15.41 mSv/year at respective locations and would allow an endoscopist standing at bedside for these cases to remain within NRC occupational dose limit of 50 mSv annually.Table 1.: Depicts the energy output in kVp and mA as well as the measurement of radiation in a volume of air (mR/hr) for each device, image mode, and location. kVp = Kilovoltage peak; mA = Milliamperage; mR/hr = Milliroentgen per hourTable 2.: Depicts stochastic biological risk of ionizing radiation in rates of Millisievert, which is the commonly used SI (International System of Units) measurement. Shown above in rates per hour, case, and year. In this study, a case represents 8 minutes of fluoroscopy time, which is the average per ERCP. A year consists of 850 ERCP cases, which is the approximate ERCP case load in our Endoscopy Center at UMMCImage 1.: Demonstrates the experimental set-up used to simulate an endoscopic case with fluoroscopic guidance. Here, a Fluke 451 Ion Chamber Survey Meter is used to measure ionizing radiation from bedside at typical position of endoscopist.