简述射线照相检测方法的缺陷检出灵敏度与对比度和可见度之间关系，射线照相灵敏度与产品透照技术等级、缺陷评定质量级别的关系和重要性。介绍检出缺陷尺寸几个关系式，说明影响检出缺陷灵敏度的主要因素及标准中的几个隐含参量。射线检测人员在实际工作中，在考虑影响因素的同时，可用公式计算结果预计所能达到的检测灵敏度。

The relationship of sensibility, contrast and visibilities of ray photography flaw detection was briefly introduced, as well as the relationship and importance of ray photography sensibility, grades of products photography technology and flaw evaluations grades. Some formulae were introduced for checking flaw size, derivation of the formulae and their relations, main factors affecting sensibility of flaw detection, hidden parameters in the standard. The above mentioned formulae might be useful for ray detection workers during their practical work to predict the sensibility and accuracy while considering the affecting factors.