Abstract:
Background ERCP is often performed in a patient either lying prone or lying left lateral decubitus. Automatically, the adjustment function of beam parameters in a thicker object results in the increasing radiation dose to improve the image quality. Hypothetically, a patient lying left lateral decubitus produces higher scatter radiation when compare with the one lying prone. This hypothesis holds true to ERCP personnel. In addition, the radiation exposure inversely relates to the square of the distance between the personnel and the focal spot of the x-ray tube. There are many personnel involved during ERCP procedure, which the absorbed dose at different standing position may be different.. Objective To compare the effective dose among personnel performing ERCP and stand at different locations in ERCP room and during different patient positions (prone and left lateral decubitus). Methods From July - October 2015, 54 patients undergoing ERCP at King Chulalongkorn Memorial Hospital were randomized into prone and left lateral decubitus positions. Patients who needed ERCP at the fixed position were excluded. All personnel wore a wrap-around lead apron and thyroid shield as recommended. The solid-state dosimeter (DoseAware; Philips, Amsterdam, The Netherlands) was attached over the thyroid shield of each personnel who worked around the ERCP table (1oendoscopist, 2oendoscopist, and nurse anesthetist). After ERCP procedure, all three dosimeters were read and fluoroscopic time was recorded. The effective doses per fluoroscopic time of each personnel were calculated and compared based on the assigned positions. Results Age, gender, BMI, indication for ERCP, and fluoroscopic time were not different between 2 groups (table). The mean effective doses per fluoroscopic time (mSv/min) of the 1oendoscopist and nurse anesthetist were statistically higher in lying left lateral position than lying prone position (8.30 vs. 5.13, p= 0.002 and 10.92 vs. 4.87, p= 0.0001, respectively). Based on the new recommended dose limit for the lens of the eye (20mSv/yr : ICRP Publication118), the calculated maximum number of cases per year for each personnel without wearing radiation protective eyewear in patient lying prone and lying left lateral position were 600 cases and 500 cases for the 1oendoscopist , 700 cases and 400 cases for nurse anesthetist respectively. Conclusions Nurse anesthetist and the 1o endoscopist almost equally exposed to radiation. The effective dose the nurse anesthetist and the 1o endoscopist received during ERCP from a patient lying left lateral decubitus are almost double that received from the patient lying prone. To exceed the annual calculated limited number of cases but still safe from overexposure, changing the patient to prone position and/or wearing radiation protective eyewear are recommended.