放射性活度计在其电离室垂直方向上的响应分析  

Response of radioactivity meter in vertical direction of ionization chamber

作　　者：宋颖[1] 刘辉[1] SONG Ying;LIU Hui(Key Laboratory of Radiological Protection and Nuclear Emergency,China CDC,National Institute for Radiological Protection,Chinese Center for Disease Control and Prevention,Beijing 100088 China)

机构地区：[1]中国疾病预防控制中心辐射防护与核安全医学所,辐射防护与核应急中国疾病预防控制中心重点实验室,北京100088

出　　处：《中国辐射卫生》2023年第3期250-253,共4页Chinese Journal of Radiological Health

摘　　要：目的通过测量不同的放射源测试放射性活度计在电离室垂直方向上不同位置的响应变化。方法利用临床常用类型放射性活度计测量铯-137、钴-60和镅-2413种核素在电离室垂直方向不同位置的示值,分别拟合出变化趋势线,根据趋势线预估测量值最大偏差,并预估使用不同注射器时的测量值偏差。结果根据拟合结果预测活度计CRC-55tR测量铯-137、钴-60和镅-2413种核素的最大偏差分别为5.15%、5.98%和6.25%。使用RM-905a放射性活度计模拟不同注射器针管高度测量3种核素,得最大偏差分别为-4.33%、-9.9%和-12.65%。结论3种不同能量的核素在CRC-55tR和RM-905a 2种活度计中的变化趋势不同,但在同一活度计中趋同。同一活度计中电离室垂直方向上不同位置的测量值偏差较大,不可忽略,建议工作中针对常用核素做位置修正,减少测量误差,提高核素测量精度对辐射防护工作具有重要意义。Objective To determine the responses of radioactivity meter at different positions in the vertical direction of the ionization chamber by measuring different radioactive sources.Methods The radiation of cesium-137,cobalt-60,and americium-241 nuclides was measured at different positions in the vertical direction of the ionization chamber with commonly used clinical radioactivity meters.The measured values were fitted to obtain three trend lines.The maximum deviation of the measured values was estimated according to the trend line,and the deviation was estimated at different syringe needle heights.Results According to the trend lines,the maximum deviation of the radioactivity meter CRC-55tR in measuring cesium-137,cobalt-60,and americium-241 nuclides was 5.15%,5.98%,and 6.25%respectively.The radioactivity meter RM-905a was used to measure three nuclides at different syringe needle heights,and the maximum deviations were−4.33%,−9.9%,and−12.65%,respectively.Conclusion The three nuclides showed different change patterns in measurement with CRC-55tR and RM-905a but similar change patterns in measurement with the same radioactivity meter.The values measured with the same radioactivity meter showed significant deviations at different positions in the vertical direction of the ionization chamber.It is recommended to make position correction for commonly used nuclides.Reducing measurement error and improving measurement accuracy of nuclides are of great significance for radiation protection.

关 键 词：核医学 放射性活度计 活度 辐射防护 

分 类 号：TL81[核科学技术—核技术及应用]