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本文研制了一台测量电子束和β射线吸收剂量的外推电离室,其空腔室壁材料可拆换并分别与空气、组织和硅等效,收集电极名义直径为1.5、3、10和30mm,空气空腔可变范围为0.2～15mm。该外推电离室具有在空腔内部测温,自动改变窗口上方材料厚度及采用微型计算机控制等特点。适用于测10 MeV能量以下,剂量率为10~5～10~(-3)Gy/h的电子或β射线吸收剂量。整个外推电离室自动测剂量系统在测~(204)TLβ放射源表面剂量率的不确定度为2.3％。测1.5 MeV电子束在硅和哈密瓜深部剂量率时,不确定度分别为4.0％和2.8％。
In this paper, an extrapolated ionization chamber for measuring the dose of electron beam and β-ray absorption has been developed. The material of the cavity wall is removable and equivalent to air, tissue and silicon respectively. The nominal diameters of the electrodes are 1.5, 30mm, air cavity variable range of 0.2 ~ 15mm. The extrapolation ionization chamber has a temperature measurement in the cavity, automatically changing the thickness of the material above the window and using microcomputer control. It is suitable for electron or beta-ray absorption dose of 10 ~ 5 ~ 10 ~ (-3) Gy / h below 10 MeV. The uncertainty of the dose rate at the surface of ~ (204) TLβ radioactive source is 2.3% for the whole extrapolated ionization chamber automatic dosimetry system. The uncertainty of the deep dose rate of 1.5 MeV electron beam at silicon and melon was 4.0% and 2.8%, respectively.