[Measurement as a Personal Dose Equivalent of X-ray Room Scattered Dose in ERCP Inspection]

In the revised Regulation on Prevention of Ionizing Radiation Hazards (April 2020), the equivalent dose limit for the lens of the eye was lowered to "100 mSv in 5 years and 50 mSv in 1 year." It is necessary to reduce occupational exposure in the healthcare sector. The purpose of this study was to facilitate comparison with the equivalent dose limit in an endoscopic retrograde cholangiopancreatography (ERCP) examination by measuring the scattered dose in an X-ray room as an individual dose equivalent.

The scattered dose was measured by dosimeters positioned in a grid pattern in the X-ray room. The dose rate was measured with and without the use of a protective cloth (0.25 mm Pb equivalent) suspended around the X-ray tube extending to the patient. The dose reduction rate of the material was evaluated during the simulated ERCP.

The maximum dose rate at the position of the surgeon performing an ERCP inspection in the standing position was 2.9 mSv/h (3 mm dose equivalent rate) at 150 cm from the ground. The number of ERCP examinations to comply with the equivalent dose limit of the equivalent dose of the lens of the eye without the protective cloth was 28 per year.

The results of this study suggest that individual dose equivalent measurements in the X-ray clinic may facilitate comparison with the equivalent dose limit.