Evaluation of Organ Doses for Pediatric Computed Tomography Using a Newly Designed Radiophotoluminescence Glass Dosimeter and Comparison with a Monte Carlo Simulation-based Dose Calculator

Abstract

Management of patient dose is an effective way to help optimize computed tomography (CT) scanning conditions and CT dose. Organ dose is one of the preferred quantities for radiation protection because of its correlation with radiation risk. To date, the WAZA-ARI dose calculator is the only freely available CT dose calculator also applicable for pediatric patients. However, no reports of its evaluation have appeared since the latest version of WAZA-ARI was released. In this study, to evaluate the latest version of WAZA-ARI, we measured the organ dose in a 5-y-old anthropomorphic phantom by a newly developed radiophotoluminescence glass dosimeter (RGD) dosimetry system and compared these results with the calculation results from WAZA-ARI. The newly designed RGDs have less angular dependence because of the additional filter. RGDs were individually calibrated with the ISOVOLT TITAN-320 x-ray generator. All the experimental measurements for this study were performed using a CT scanner. To consider the difference of CT output between the nominal and actual machine, the measured CTDI_air was used to correct the calculation results obtained from WAZA-ARI. After the corrections using the measured CTDI_air, the calculation results from WAZA-ARI were relatively lower than the measured results with a range of 8–20%, which corresponds to the dose difference caused by the difference in effective diameter. In conclusion, the calculation accuracy of WAZA-ARI is guaranteed when the normalization factor specific to each CT scanner (CTDI_air) and the shape of the phantom are taken into consideration.