水量热法^(60)Coγ射线水吸收剂量的绝对测量  

Absolute measurement of absorbed dose to water forγ-ray of ^(60)Co by water calorimetry

作　　者：杨乾[1] 范杰[1] 许诗朦 YANG Qian;FAN Jie;XU Shimeng(National Institute of Measurement and Testing Technology,Chengdu 610021,China)

机构地区：[1]中国测试技术研究院,成都610021

出　　处：《核技术》2024年第7期25-31,共7页Nuclear Techniques

基　　金：四川省科技计划项目专项(No.2023JDKY0040)资助。

摘　　要：目前国内大多数放射治疗剂量只能溯源到^(60)Co γ射线空气比释动能,与溯源至空气比释动能相比,将放射治疗剂量直接溯源至水吸收剂量的不确定度要小很多。为了解决^(60)Co γ射线水吸收剂量量值溯源与传递问题,进一步提升^(60)Co γ射线水吸收剂量的量值溯源与传递能力,中国测试技术研究院(National Institute of Measurement and Testing Technology,NIMTT)采用水量热法建立了^(60)Co γ射线水吸收剂量绝对测量装置,实现了水吸收剂量的绝对测量,复现了^(60)Co γ射线水吸收剂量,其量值复现的相对标准不确定度为0.45%。为了进一步验证^(60)Co γ射线水吸收剂量复现结果的准确性与一致性,将NIMTT实验室与加拿大国家研究委员会(National Research Council,NRC)实验室的复现结果进行了实验室之间的比对,结果在相对标准不确定度0.71%以内呈现一致性,归一化误差En值为-0.45。表明NIMTT具有^(60)Co γ射线水吸收剂量量值溯源与传递的能力,本研究结果也为^(60)Co γ射线吸收剂量的绝对测量提供了参考。[Background]Most of domestic radiation therapy doses can only be traced back to air kerma of ^(60)Coγ-ray at present in China.The uncertainty of directly tracing radiation therapy dose to absorbed dose to water is much smaller compared to tracing radiation therapy dose to air kerma,which must be converted to absorbed dose to water.[Purpose]This study aims to solve the problem of traceability and transfer of ^(60)Coγ-ray absorbed dose to water,as well as the problem that the dose measurement of radiotherapy cannot be directly traced through the absorbed dose to water,NIMTT(National Institute of Measurement and Testing Technology)has established an absolute measurement device of ^(60)Coγ-ray absorbed dose to water.[Methods]An absolute measurement device of ^(60)Coγ-ray absorbed dose to water was established by National Institute of Measurement and Testing Technology(NIMTT)using water calorimeterfor direct measurement of absorbed dose to water.The correction factors for water absorbed dose measurement were obtained by experimental and simulation methods.A comparison of laboratory reproducing results was made between NIMTT and NRC(National Research Council,Canada)using the method of transmitting standard to further verify the accuracy and consistency of the measurement of ^(60)Coγ-ray absorbed dose to water.Two PTW ionization chambers were used as the transfer standard.[Results]The reproduced results of two laboratories for absolute measurement of ^(60)Coγ-ray absorbed dose to water are consistent within the relative standard uncertainty of 0.71%,and the normalized error value of En is-0.45.[Conclusions]The comparison results have verified that NIMTT laboratory has the ability of traceability and transmission of absorbed dose to water.The results of this study provide a reference for the absolute measurement of absorbed dose to water for ^(60)Coγ-ray.

关 键 词：水量热法 水吸收剂量 电离辐射 绝对测量 

分 类 号：TB98[一般工业技术—计量学]