Performance Characterization of an Inorganic Scintillation Dosimeter Under 6 MV Photon Beam With Temporal Separation of Cerenkov Radiation

Abstract

This study aimed to evaluate the performance of a inorganic scintillating detector (ISD) based on the Gd2O2 S:Tb scintillator, when employing the temporal filtration technique for Cerenkov radiation elimination. The investigation includes physical measurements such as repeatability of the output signal, angular dependence, and percentage depth dose (PDD) profiles across varying field sizes and Monte Carlo (MC) simulation of the measured PDDs. Very good output signal stability was calculated across different radiation doses, with maximum deviations of 1.10% and 0.55% at 20 and 100 MU, respectively. However, the geometrical design of the dosimeter sensitive volume resulted in a pronounced angular dependence with a maximum deviation of 19% at a gantry angle of 90◦ in the azimuthal configuration. The results of the MC simulation show discrepancies between the measured and simulated profiles, even after accounting for Cerenkov radiation and absorbed dose energy dependence, suggesting that factors related to the intrinsic energy dependence of the Gd2O2S:Tb material influence the ISD’s response at depth. These findings highlight the system potential for radiotherapy applications while stressing the need for further design optimization to reduce angular dependence, and for a deeper understanding of material-specific scintillation behavior affecting dosimetric performance.