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本文总结了天然铀(+子体)块作为β射线外照射吸收剂量刻度用参考标准源的7个优点。用组织等效外推电离室测量了天然铀照射聚乙烯材料时的深部剂量分布。用裸露胶片测量了源中心轴上空气中浅表吸收剂量随源到探测器距离的变化,以及不同距离处垂直于中心轴的平面上剂量场的均匀性。指出了按照ICRU第39号报告提出的定向剂量当量H’(0.007)和浅表个人剂量当量H_?(0.007),用这种源刻度环境或工作场所监测仪表和个人剂量计时应注意的问题。最后把测量值与根据天然铀及其主要子体的复杂能谱进行的初步理论估算值进行了比较,符合较好。
This article summarizes seven advantages of a natural uranium (+ daughter) block as a reference source for external dose absorption of beta rays. Depth dose distribution of natural uranium irradiated polyethylene material was measured by tissue equivalent extrapolation ionization chamber. The variation of the superficial absorbed dose in the air of the source center axis with the distance from the source to the detector and the uniformity of the dose field in the plane perpendicular to the central axis at different distances were measured with bare film. Indicate the issues to be aware of using this source scale for environmental or workplace monitoring instrumentation and personal dose timing in accordance with Directive dose equivalent H ’(0.007) and superficial individual dose equivalent H _? (0.007) as reported in ICRU Report 39. Finally, the measured values are in good agreement with the preliminary theoretical estimates based on the complex energy spectra of natural uranium and its major progeny.