P121] Measurements of the scattered and leakage radiation in chest X-ray facilities

Abstract

Purpose The chest X-ray (CXR) examination is the most frequently employed radiographic procedure for screening and diagnosis of diseases because it provides substantial clinical information at a low cost and minimal radiation exposure. Despite its enormous benefits, the ionizing nature of x-rays poses potential health risks to patients, medical personnel and general public. In this study, safety assessment of CXR facilities of selected public hospitals was performed through scattered and leakage radiation measurements. Methods Scattered radiation measurements of CXR machines were conducted using a survey meter. Dose rates were obtained from 20.7 cm polymethylmethacrylate (PMMA) phantom for both postero-anterior (PA) and antero-posterior (AP) projections. Dose rate maps were generated at distances of 50, 100, 150 and 200 cm at different angles around the phantom. Measurements performed in the control room using typical clinical irradiation conditions were used to obtain the calculated annual doses of the facilities. Leakage radiation measurements were also performed at 100 cm distance from the focus of the four sides of the X-ray tube with the collimators completely closed. Measured and calculated dose rates were evaluated with respect to the acceptable limits set by the International Commission on Radiological Protection (ICRP). Results For both CXR projections, the scattered radiation dose decreased as the distance from the center of the phantom was increased. The largest drop was observed at an angle of 225° with the dose rate at 200 cm dropping to 1.1% of the dose rate in 50 cm. Moreover, the AP projection produced higher scattered radiation than the PA projection due to the shorter source-to-image distance (i.e., 180 cm for PA and 100 cm for AP). The highest leakage radiation dose rate was 5.969 μ Sv/hr and the calculated annual dose rates were 1846 nSv/yr and 20.34 nSv/yr. These values were found to be below the leakage radiation and occupational dose limits set by ICRP which are 1000 μ Sv/hr and 20 × 10 6 nSv/yr, respectively. Conclusions Through the scattered and leakage radiation measurements, it was proven that existing procedures in the facilities evaluated do not pose significant threats on patients, medical personnel and the general public.