医用加速器高能光子束水吸收剂量测量及不确定度分析

针对电离室的⁶⁰Co水吸收剂量校准因子使用中存在的问题,对NIM在⁶⁰Co辐射场下校准电离室的水吸收剂量进行了研究。针对校准电离室和校准医用加速器时所考虑修正项的差异,对各修正项进行分析。通过不确定度分析得出⁶⁰Co辐射场下校准电离室的不确定度为0.71%,传递到加速器高能光子束下水吸收剂量的不确定度为1.30%。最后,给出医用加速器高能光子束水吸收剂量校准时的建议和注意事项。

Measurement and Uncertainty Analysis of Absorbed Dose to Water of High-energy Photons in Medical Accelerator

In view of the doubts in the use of ⁶⁰Co absorbed dose to water calibration factor in the ionization chamber, the calibration factor of absorbed dose to water given by NIM was described in detail. According to the difference of correction items between calibrating ionization chamber and medical accelerator, the correction items were analyzed. The uncertainty of calibration chamber in ⁶⁰Co radiation field is 0.71%, and the uncertainty of absorbed dose to water of high-energy photons in accelerator is 1.30%. Finally, the suggestions and precautions for calibrating absorbed dose to water of accelerator high-energy photons were given.