Clinical Validation of myOSLchip system for Radiotherapy Dosimetry

Abstract

In radiation oncology, inter-fractional dosimetry is often performed with luminescent dosimeters to verify the accurate delivery of a plan and ensure patient safety. Optically stimulated luminescent detectors (OSLDs) are the most commonly used detector type which offers good dose linearity and accuracy in the megavoltage energy range. Freiberg Instruments offer a dosimetry system under the brand name myOLSchip which consists of a BeO OSL dosimeter, reader, and eraser. A Varian Truebeam was used to characterize the detectors and calibrate their response in order to perform in-situ dosimetry during treatment. The OSLDs were tested with both photon and electron beams from 6-15 MV and 6-20 MV respectively. The dose signal to dose conversion in this investigation follows the recommendations of TG-191 in developing a dose response curve and creating a batch calibration factor for each dosimeter. The repeatability of this system is also investigated following successive erasing and re-irradiation cycles. The results of this data have been compared to the stated accuracy and precision of the BeO detectors by the manufacturer and shown to have good dose linearity and repeatability across multiple exposures and erasure cycles.