Dosimetric calibration of nanodot optically stimulated luminescent dosimeter for intraoperative radiotherapy with low-energy X-rays

The purpose of this study was to evaluate the dosimetric characteristics of optically stimulated luminescent dosimeters (OSLDs) for application in intraoperative radiotherapy (IORT). Dose measurements were performed using a customized phantom fabricated using a three-dimensional (3D) printer and a low-energy (50 kV) X-ray INTRABEAM ™ system (Carl Zeiss Surgical GmbH, Oberkochen, Germany). The phantom was equipped with a housing slot for the placement of parallel plate ionization chamber or OSLD. Dosimetric characteristics of the OSLD, i.e. radiation sensitivity, linearity, and reproducibility, were analyzed. In addition, the variation in sensitivity after the irradiation with high dose was estimated. After the irradiation of 1 Gy to the 80 OSLDs, measured doses were to range between 0.92 Gy and 1.04 Gy, with an average sensitivity of 2.1%. To ensure the reproducibility of the OSLDs, the sensitivity was reduced via repeated measurements—a decrease in sensitivity of approximately 6% is observed. After the irradiation with high dose, evaluation of reproducibility revealed variations in sensitivity, with an average sensitivity of 2.9%. Therefore, the dosimetric corrections are necessary for the OSLD based on measurements in IORT environments. The use of the aforementioned correction factors is expected to improve the precision of in vivo dosimetry during IORT.