用治疗级电离室测量短脉冲高剂量率X射线的实验研究

目的:探索研究治疗级电离室用于短脉冲高剂量率X射线的快速测量。方法:利用内插法测量某电子加速器装置所致脉冲X射线半值层，估算其等效能量；采用治疗级电离室和热释光测量方法，对比设备周围同一方向不同距离处相同数量脉冲辐射的累积剂量；分析电离室剂量仪测量结果与源距离之间的关系，对比不同频率下同一位置相同数量脉冲辐射的累积剂量...

Experimental study on measurement of short pulsed and high-dose-rate X-ray by therapeutic grade ionization chamber

Objective To investigate the application of therapeutic grade ionization chamber to rapid measurement of short pulsed and high-dose-rate X-ray.Methods The half-value layer of pulsed X-ray caused by an electron accelerator was measured by interpolation method and its equivalent energy was estimated. The cumulative doses from a certain amount of pulsed radiation at different distances in the same direction around the equipment were compared using the therapeutic grade ionization chamber and thermoluminescence measurement method. The relationship between the measurement result by using ionization chamber dosimeter and the distances away from source was analyzed. The cumulative doses from a certain amount of pulsed radiation at the same location at different frequencies were compared.Results In working condition, 100 pulses of radiation were received accumulatively at 1 to 12 meters away from the outer wall of the equipment. The range of air Kerma was 0.08-9.65 mGy measured by using thermoluminescence dometers and 0.08-9.85 mGy using the ionization chamber dosimeters, respectively. The difference between both is within 10%. At different frequencies (1-10 Hz), there was no significant difference in X-ray air Kerma from 100 pulses measured by ionization chamber dosimeter at 2 m away from the front of the equipment (P>0.05).Conclusions The therapeutic grade ionization chamber dosimeter can be used for the rapid measurement of short pulsed X-ray radiation dose in the range of dose rates and pulse frequencies involved in the experimental accelerator device.