电容积分式放射性活度计的研制  

Development of a capacitance-integrating radioactivity meter

作　　者：何铭蔓 张京隆 杨洪 HE Mingman;ZHANG Jingong;YANG Hong(College of Nuclear Technology and Automation Engineering,Chengdu University of Technology,Chengdu 610059,China)

机构地区：[1]成都理工大学核技术与自动化工程学院,成都610059

出　　处：《核技术》2024年第7期57-64,共8页Nuclear Techniques

基　　金：国家自然科学基金(No.11805023)资助。

摘　　要：现场快速准确地实现放射性核素活度测量在放射性医学诊断中具有重要作用。本文采用电容积分式的电路结构,设计了低噪声前置放大电路与高精度信号采集与处理电路成功研制出弱电流测量电路,实现了20 fA~10μA弱电流测量。结合前端井型电离室,搭建了电容积分式放射性活度计原型装置。测试结果表明:本文研制的放射性活度计重复性与商用RM-905A性能基本一致,本底小于0.065 MBq,重复性不超过0.84%,不稳定性为1.94%。[Background]Rapid and accurate measurements of radionuclide activities in the field play an important role in radiological medical diagnosis.[Purpose]This study aims to develop a capacitance-integrated activity meter.[Methods]A circuit structure of the capacitive-integral type was adopted to design a low-noise preamplifier circuit.The designed structure was matched with high-precision signal acquisition and processing circuit to successfully develop a weak current measurement circuit,achieving weak current measurements ranging from 20 fA to 10μA.The Geant4 simulation software was employed to simulate the ionization chamber used in the current design to obtain correction factors for different nuclides.Finally,three different radiation sources were used for performance testing of this self-developed radioactivity meter,and compared with a commercial RM-905A radioactivity meter.[Results]The test results show that the repeatability of the proposed radioactivity meter is consistent with the performance of the commercial RM-905A radioactivity meter,with a background lower than 0.065 MBq,a repeatability of 0.84%at most,and an instability of 1.94%.[Conclusions]The capacitive integral radioactivity meter developed in this study can be used as an alternative instrument for commercial radioactive activity meter RM-905A.

关 键 词：放射性活度计 4πγ电离室 电容积分式I-V转换 现场可编程门阵列 

分 类 号：TL99[核科学技术—核技术及应用]