用于测定β敷贴器表面剂量率的外推电离室  

EXTRAPOLATION IONIZATION CHAMBER FOR DETERMINING SURFACE DOSE RATE OF BETA APPLICATORS

作　　者：陈慧莉[1] 姚小丽[1] 杨俊武[1] 王川[1] 张延生[1] 

机构地区：[1]中国辐射防护研究院

出　　处：《辐射防护》1996年第6期423-429,共7页Radiation Protection

摘　　要：本文描述了两种用于测量医用β敷贴器表面剂量率的外推电离室的设计原理、结构、性能和实验结果。一种的收集极和保护环块用喷涂小于０．０５ｍｍ的石墨层的聚苯乙烯材料做成；另一种的收集极和保护环块是由石墨块作成的分立的同心体。两种外推室的极间距行程均为０－１０ｍｍ，槽沟宽度均小于０．３ｍｍ，入射窗用７ｍｇ·ｃｍ－２厚度的铝化聚脂膜加聚脂膜构成；均能方便地更换（不同尺寸和材料）收集极和调节极间距。前一种在几十Ｇｙ照射后一小时，即可恢复到正常本底水平；后一种在几十Ｇｙ照射后，立即恢复到正常本底水平；解决了测量大剂量时克服“记忆效应”The design principle, structure, preformance and experimental results of two types of extrapolation ionization chamber are described in this paper. Both of them are used for measuring the surface dose rate of beta medical applicators. The collecting electrode and guard ring of one chamber were made of polystyrene with 0.05 mm graphite surface coating, while, the collecting electrode and guard ring of another chamber were constructed by a separate concentric circle with graphite block. For both chambers, the range of 0-10 mm of the gap between the high voltage electrode and the collecting electrode is adjusted. The groove width or the spacing between the collecting electrode and the surrounding guard ring are less than 0.3 mm. The incidence window was made of aluminizing mylay film. It is very easy to exchange the collecting electrode (different sizes and material) and to adjust the space between electrodes. For the former, after several decades of Gy irradiation, and about one hour later, its leakage current could be recovered to normal background level; while for the latter, in the same irradiation situation the leakage current can be recovered to normal background level immediately. Therefore, the problems dealing with very high dose rate measurement “memory effect”, has been solved. (

关 键 词：β敷贴器 外推 电离室 记忆效应 皮肤病 

分 类 号：TH784[机械工程—仪器科学与技术] TL818.9[机械工程—精密仪器及机械]