^(60)Co γ射线水吸收剂量量值传递方法初步研究

Preliminary Study on the Quantitative Value Transfer Method of Absorbed Dose to Water in ^(60)Co γ Radiation

60Co γ射线水吸收剂量是放射治疗体系的基础物理量,在辐射治疗中发挥着重要作用。开展60 Coγ射线水吸收剂量值传递方法研究,可为我国γ射线水吸收剂量量值体系的建立提供重要技术支持。以PTW-30013电离室、PMMA水箱及三维移动平台为基础,建立量值传递标准装置;结合IAEATRS398报告的要求开展60 Coγ射线水吸收剂量量值传递方法的初步研究。经量值传递后,PTW-30013电离室60 Coγ射线水吸收剂量校准因子的扩展不确定度为0.90%(k=2),辐射计量中心(IAEA次级标准计量实验室)60 Co参考辐射γ射线水吸收剂量的扩展不确定度为1.4%(k=2)。结果表明,该量值传递方法可有效降低次级标准剂量实验室60 Coγ射线水吸收剂量的测量不确定度。

Absorbed dose to water in ^60Coγ radiation is the basic physics quantity in the quantitative value system of radiation therapy, it is very necessary for radiation therapy. The study on the quantitative value transfer method of absorbed dose to water in ^60Coγ Radiation could provide important technical support to the establishment of Chinese absorbed dose to water quantity system. Based on PTW-30013 ionization chamber, PMMA water phantom and 3D mobile platform, quantitative value transfer standard instrument was established, combined with the requirement of IAEA-TRS398, developed preliminary study of ^60Co absorbed dose to water quantity value transfer method. After the quantity value transfer, the expanded uncertainty of absorbed dose to water calibration factor of PTW-30013 was 0. 90% （k = 2）, the expanded uncertainty of absorbed dose to water of ^60Coγ reference radiation in Radiation Metrology Center （SSDL of IAEA） was 1.4% （k=2）. The results showed that, this value transfer method can reduce the uncertainty of ^60Co absorbed dose to water effectively in Secondary Standard Dosimetry Laboratory.