The difference in ocular lens equivalent dose to ERCP personnel between prone and left lateral decubitus positions: a prospective randomized study

BACKGROUND AND STUDY AIMS: Endoscopic retrograde cholangiopancreatography (ERCP) is commonly performed in a prone or left lateral decubitus (LLD) position. The ocular lens equivalent doses between the two positions may be different because in the LLD position the tube voltage will automatically increase to maintain the image quality, and the increased distance between the image intensifier and the X-ray tube may result in more scattered radiation. We aimed to compare the ocular lens equivalent doses of ERCP personnel between the two different positions. PATIENTS AND METHODS: Fifty-five patients with ERCP indications were randomized to either prone or LLD positions. One patient in an LLD position was excluded due to technical reasons. Indications for ERCP, patients’ vertical thicknesses, fluoroscopy parameters, patients’ skin dose rates, and the ocular-lens equivalent doses of ERCP personnel were compared. RESULTS: Baseline characteristics were no different except for vertical thickness, which was significantly higher in the LLD group. The ocular lens equivalent doses (prone vs. LLD) of the primary endoscopist (19.2 vs. 30.7 µSv, P = 0.035), and the nurse anesthetist (17.3 vs. 42.2 µSv, P = 0.002) were significantly lower in the prone group than in the LLD group. The calculated annual number of procedures not to exceed the exposure allowance in prone and LLD positions were 1,042 and 651 procedures for the primary endoscopist and 1,157 and 473 procedures for the nurse anesthetist, respectively. CONCLUSIONS: Ocular-radiation exposure to ERCP personnel was one-third lower in the prone than in LLD position. Therefore, more annual ERCPs could be performed by the personnel.