Clinical characterization of BeO OSLDs: High dose response and extended energy dependence

Beryllium oxide (BeO) optically stimulated luminescent dosimeters were characterized across a broad range of energies and doses to evaluate their suitability for clinical dosimetry applications beyond manufacturer-specified limits. Seventy-eight unscreened BeO dosimeters were evaluated for sensitivity, stability, dose linearity, energy dependence, and signal depletion using clinical radiation sources spanning kilovoltage photons (100–320 kVp), megavoltage photons (6–18 MV), and electron beams (6–20 MeV). Dose response was assessed from 0.5 to 50 Gy, and signal depletion was quantified over ten successive readouts at multiple post-irradiation time points. Individual dosimeter sensitivities varied from 0.8 to 1.3 relative to the batch mean, while 75% demonstrated a coefficient of variation below 1% across repeated measurements, indicating good reproducibility. Dose response remained linear up to approximately 30 Gy, with saturation observed near 40 Gy. No degradation in dose calibration accuracy was observed for accumulated doses up to 50 Gy, and a small sensitivity shift at 100 Gy remained within predefined equivalence bounds. A pronounced under-response of 25–40% was observed at kilovoltage energies relative to megavoltage photons, whereas responses across megavoltage photon and electron beams were stable within ±2%. Signal depletion was consistent at approximately 1% per readout and independent of post-irradiation time. These results define the operational limits of unscreened BeO dosimeters and support their use in clinical dosimetry, provided that energy-specific calibration is applied for kilovoltage applications.