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目的在我国放疗剂量检测不是直接测量水中的吸收剂量,而是先测量照射量或空气比释动能,再通过相关的剂量学规范采用多种修正因子把测量结果转换为吸收剂量,本文将探讨采用不同的剂量学规程测量吸收剂量所产生的偏差。方法本文利用ICRU23、IAEA 277和IAEA 398号技术报告三种放疗剂量学规程对不同型号的电离室在~(60)Coγ射线辐射场中同样条件下分别测量水中的吸收剂量,进行了比对实验研究,分析不同型号的探测器分别采用三种规程所测得的实际剂量差别。结果通过对10个6种型号的电离室在~(60)Coγ射线辐射场中同样条件下分别测量水中的吸收剂量,发现采用三种规程引起的偏差在2%以内,同时,发现不同型号的电离室之间也存在一定的分散性。结论使用不同的剂量学规程进行放疗剂量的测量会引入较大的偏差,为降低我国放疗剂量测量的不确定度,应尽快建立水吸收剂量量值传递系统。
The purpose of radiation dose detection in our country is not to directly measure the absorbed dose in water but to measure the exposure or air kerma and then to convert the measurement results into absorbed dose by the relevant dosimetry norms. Different dosimetry protocols measure deviations from the absorbed dose. Methods In this paper, the ICRU23, IAEA 277 and IAEA 398 techniques were used to report the dosimetry protocols of three radiotherapy dosimeters respectively to measure the absorbed dose in water of different types of ionizing chambers under the same conditions of ~ (60) Coγ-ray radiation field. Research, analysis of different types of detectors were used to determine the actual dose of three different procedures difference. Results By measuring the absorbed dose of water in the ionization chamber of 6 different types in the same condition of ~ (60) Coγ-ray radiation field, the deviations caused by the three procedures were found to be within 2%. At the same time, different types of There is also some dispersion between the ionization chamber. CONCLUSION: The measurement of radiotherapy dose using different dosimetry protocols will lead to large deviations. To reduce the uncertainty of radiotherapy dose measurement in our country, a water-absorbed dose quantity delivery system should be established as soon as possible.