[Properties and usage of radiophotoluminescent glass dosimeters for computed tomography dosimetry]

There are two types of radiophotoluminescent glass dosimeters (RPLDs). One has a tin filter in the capsule (GD-352M) and the other has no filter (GD-302M). The purpose of our study was to evaluate the properties of these RPLDs for computed tomography (CT) dosimetry: energy dependence, variation, angular dependence, and dose distribution in a single slice. Energy dependence and variation were investigated for ratio of the air kerma measured by RPLDs to that by ion chamber. Angular dependence was investigated for RPLDs and ion chamber. RPLDs were irradiated at 90°, 60°, 30°, 0°, -30°, -60°, and -90°: 0° was vertical to long axial direction of the RPLD, and plus and minus meant clockwise and anti-clockwise, respectively. Dose distribution in a single slice of an anthropomorphic phantom was acquired using 46 RPLDs. The dose responses of GD-302M and GD-352M depended on beam energy and irradiation angle of X-ray, respectively. The dose variation among dosimeters was large with GD-352M. The dose obtained from GD-352M was lower than that from GD-302M. It was expected that the dose distribution of GD-352M was formed by the primary X-ray, so RPLD without tin filter should be used for CT dosimetry.