Feasibility of dosimetry with optically stimulated luminescence detectors in magnetic fields

摘要

AbstractThe objective of this study was to analyze the applicability of optically stimulated luminescence detectors (OSLDs) for dosimetry in magnetic resonance (MR) guided radiation therapy devices with focus on dose dependence and angular dependence on the magnetic field strength.Precise detectors for dosimetry in high magnetic fields for such devices are still subject to research. In contrast to ionization chambers, OSLDs contain no air cavities, such that only minor changes in detector response with increasing magnetic field strengths are expected.To study the behavior of OSLDs in magnetic fields, Al2O3:C detector packages were irradiated at a 6?MV linac in a water phantom, while magnetic fields between 0.0?T and 1.0?T were applied. In order to study the angular dependence, the OSLD packages were rotated around the vertical axis for three different magnetic field strengths (0.0?T, 0.5?T, 1.0?T). Additionally, the angular dependence was measured at a clinical 0.3?T60Co device. The OSLDs were read out using a portable OSL reader and an automated Ris? TL/OSL-DA-15 reader.Readout with the portable reader yielded package standard deviations of 1–2% and revealed no significant relation between dose response and magnetic field strength, while readout with the Ris? reader resulted in standard deviations of only 1% and a significant decrease in response of??1.3% per T (95%-confidence interval:??1.9% to??0