^(192)Irγ射线球形石墨空腔电离室室壁修正系数的模拟计算  

Simulation calculation of wall correction factor of ^(192)Ir gamma-ray spherical graphite cavity ionization chamber

作　　者：支世杰 王继 吴金杰[2] 王培玮[2] 任世伟[1] Zhi Shijie;Wang Ji;Wu Jinjie;Wang Peiwei;Ren Shiwei(Hebei University of Science and Technology,Shi Jiazhuang 050018,China;National Institute of Metrology,Beijing 100029,China)

机构地区：[1]河北科技大学,石家庄050018 [2]中国计量科学研究院,北京100029

出　　处：《中华放射医学与防护杂志》2022年第9期706-710,共5页Chinese Journal of Radiological Medicine and Protection

基　　金：中国计量科学研究院基本科研业务费(AKYZZ2017)。

摘　　要：目的研究192Ir放射源参考空气比释动能率基准电离室(NIM-Ir-SG-100型)的室壁修正系数。方法利用蒙特卡罗程序计算经过放射源包壳和辐照器模型的光子光谱和电离室室壁修正系数,并对影响室壁修正系数结果的光子能量、壁厚和电离室内径进行了模拟。结果经计算,球形石墨空腔电离室室壁修正系数模拟结果为1.0377。控制单一变量,光子能量(0.3~1.3)MeV、壁厚(0.2~0.5)cm、电离室内径(0.5~15)cm对室壁修正系数结果的最大偏差分别为1.62%、3.30%、2.86%。结论自制球形石墨空腔电离室性能良好,室壁修正系数k_(wall)值在合理范围内。室壁修正系数的完成为测量192Ir放射源的参考空气比释动能率,建立计量基准完成重要的一步。Objective To study the correction factor of the chamber wall of the reference air kerma rate reference ionization chamber(NIM-Ir-SG-100 type)for ^(192)Ir radioactive source.Methods The photon spectrum and ionization chamber wall correction factor of the radioactive source housing and irradiator model are calculated by Monte Carlo code.And then the photon energy,wall thickness and ionization chamber diameter,which affect the result of the chamber wall correction factor,are simulated.Results After calculation,the simulation result of the correction factor of spherical graphite cavity ionization chamber wall was 1.0377.Controlling a single variable,photon energy(0.3-1.3 MeV),wall thickness(0.2-0.5 cm),inner diameter(0.5-15 cm),the maximum deviations of wall correction result were 1.62%,3.30%and 2.86%,respectively.Conclusions The self-made spherical graphite cavity ionization chamber has good performance,and the corrected k_(wall) value of the chamber wall is within a reasonable range.The completion of the chamber wall correction factor is an important step to measure the reference air kerma rate of the ^(192)Ir radioactive source and establish the measurement benchmark.

关 键 词：石墨空腔电离室 绝对测量 室壁修正 EGSnrc模拟 

分 类 号：R144.1[医药卫生—公共卫生与预防医学]