Evaluation of a Beo-Based Optically Stimulated Luminescent Dosimetry System for In-Vivo Applications In Radiotherapy
Abstract
Purpose
This study evaluates a beryllium oxide (BeO)–based optically stimulated luminescent (OSL) dosimetry system (myOSL, RadPro Int. GmbH) for clinical radiotherapy applications.
Methods
Our institution recently implemented a BeO-based OSLD system with its dedicated reader for in-vivo dosimetry. The dosimeters consist of near water-equivalent BeO encapsulated in a thin Acrylnitril-Butadien-Styrol-Copolymer sheath having physical dimensions of 4.7×4.7×0.5 mm3. Batch calibration was performed according to vendor recommendations using conventional 6MV beam from Varian TrueBeam linear accelerator. System performance was evaluated to test dosimeter response against dose, beam energy, dose-rate and incident beam orientation. Dose linearity was tested over a dose range of 0.05-12 Gy. Energy dependence was assessed for all available photon and electron energies. Dose-rate dependence was evaluated using 6 MV and 10 MV flattening-filter-free beams. The angular dependence was assessed with beam incidence angles of 0ᵒ, 45ᵒ, 90ᵒ, and 180ᵒ. All measurements were performed with Source-to-surface distance of 100 cm using 10 x 10 cm2 field or equivalent cone size placing two or three dosimeters on central axis at respective depth-of-maximum dose in solid water slabs.
Results
The OSLDs exhibited linear dose response up to 5 Gy, beyond which deviations >5% were observed, with maximum deviation of 6.95% at 10 Gy. The average deviations across measured dose range were -1.89%±2.5%. Angular dependence showed an average deviation of -2.0%±1.0% with maximum deviation of -3.1% observed at 90ᵒ beam incidence. Dose-rate dependence for both 6 MV and 10 MV FFF beams were within 2%. Energy dependence across all beam energies was within 2% relative to 6 MV photon beam.
Conclusion
The myOSL BeO-based dosimetry system demonstrated near water-equivalent behavior with minimal dependence on beam energy, dose rate, and beam incidence angle. A mild dose-response nonlinearity was observed at doses >6 Gy. Overall, the system shows potential for reliable in-vivo measurements in radiotherapy.