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内容記述 |
A practical and accurate dosimetry method is essential to support basic research aimed at advancing ultra-high dose rate radiation therapy (UHDR, >40 Gy/s). However, applying conventional dosimetry methods which have been developed and characterized under low dose rates (approximately 0.03 Gy/s) directly to these conditions remains highly challenging. The dose and dose rate dependences of passive dosimeters, optical stimulated luminescence dosimeter (OSLD), Fricke chemical dosimeter and cellulose triacetate (CTA) film dosimeter, were investigated for dosimetry under UHDR irradiation of proton and electron beams. Under 230 MeV proton irradiation with an average dose rate of 50 Gy/s, no dose rate dependence was observed in either OSLD or Fricke dosimeter. The applicable dose range was below 10 Gy for OSLD and above 10 Gy for the Fricke dosimeter. In contrast, under 14 MeV electron irradiation with an instantaneous dose rate exceeding 100 kGy/s, dose rate dependence was observed in OSLD and CTA film dosimeter, while the Fricke dosimeter remained dose rate independent. Since the observed dose-rate dependence in OSLD appears to contradict existing theoretical models, further experimental validation is required. These results demonstrate that the dose assessment at the accelerator facilities can be effectively characterized using a combination of OSLD and Fricke dosimeters, covering a wide range of proton dose and dose rate, whereas the Fricke dosimeter is applicable for dosimetry of high-intensity short-pulsed electron beam. |
