Comparative evaluation of radiation detection capabilities of CsPbI2Br and CsPbIBr2 materials for the development of QA relative dosimeter for brachytherapy

Abstract

High-dose-rate brachytherapy is a cancer treatment that intensively irradiates tumors by inserting radioactive isotopes with high dose rates into the body. For this treatment, it is necessary to deliver an appropriate dose to the tumor tissue through an accurate treatment plan but only deliver the minimum dose to the normal tissue. Therefore, it is imperative to verify the positional accuracy of the source through accurate quality assurance (QA) in clinical practice. However, in clinical practice, the position of the source is visually determined using rulers, automatic radiographers, video monitors, and other devices, yielding inaccurate results. In this study, a semiconductor dosimeter using either CsPbI2Br or CsPbIBr2 was manufactured. The radiation detectability of both materials was tested and compared to evaluate which of the two materials would be more suitable as the QA relative dosimeter for brachytherapy. The reproducibility, linearity, and percentage interval distance (PID) of the two materials were analyzed to evaluate the radiation detectability and applicability of the relative dosimeter. In the reproducibility evaluation, the relative standard deviation (RSD) of CsPbI2Br was 0.98%, and the RSD of CsPbIBr2 was 3.45%. In the linearity evaluation, the coefficient of determination (R2) of CsPbI2Br was 0.9998, and the R2 of CsPbIBr2 was 0.9994. In the PID evaluation, both materials showed an exponential and constant decrease in measured signal sizes as the distance from the source increased. As a result of the evaluations, the CsPbI2Br dosimeter showed greater stability in detecting radiation and satisfied the evaluation criteria. In conclusion, CsPbI2Br shows promise as a digital relative dosimeter for brachytherapy QA.