水吸收剂量计性能测试

Performance test on dosimeter of absorbed dose in water

针对我国用于肿瘤治疗水中吸收剂量测量的剂量计不能直接溯源到水吸收剂量,无法与国际水吸收剂量测量方法接轨的问题,该文研制60Coγ射线水中吸收剂量绝对测量装置。为配合国内肿瘤治疗的水吸收剂量测量,对现有剂量计升级,使其更便于水吸收剂量测量,并对升级9606B剂量计的重复性、非线性和电离室的能量响应进行测试。结果表明:该剂量计的重复性、非线性、电离室能量响应均好于JJG 912——2010《治疗水平电离室剂量计》和IEC 60731——2011《用于放射治疗的电离室剂量计》中对相应参数的要求。

Domestically, the dosimeter applied to measure absorbed dose in water in oncotherapy cannot be traced directly to the absorbed dose in water but only air kerma. Thus, the absorbed dose in water is measured only by transformation of air kerma, which is not in line with international measurement method for absorbed dose in water. Therefore,NIMTT is developing an absolute measurement unit of60Coγ ray for calculating absorbed dose in water and for reoccurrence of the absorbed dose in water to solve the above mentioned problem. The existing dosimeter is upgraded for the convenience of measurement of absorbed dose in water in support of absorbed dose in water measurement in domestic oncotherapy. The repeatability,nonlinearity,and energy response of ionization chamber during upgrading of 9606 B dosimeter has been tested in this paper,the results of which shows that: the repeatability,nonlinearity,and energy response of ionization chamber are all superior to corresponding parameters requirements of the verification regulation under the Ionization chamber dosimeters used in radiotherapy(JJG 912——2010) and relevant parameters required by the Dosimeters with ionization chambers as used in radiotherapy(IEC 60731——2011).