1.1 X射线图像的图像质量和分辨率对焦点的特性特别敏感。焦点的成像质量基于其从探测器平面上看到的二维强度分布。 1.2 本试验方法提供了确定工业X射线管标准和迷你焦点有效尺寸（尺寸）的说明，焦点尺寸为100 μm至几mm的X射线源，高达600 kV管电压。较小的焦点减少到50个 µm的评估精度较低。该确定基于用“针孔”技术进行射线照相记录的焦点图像的测量。附录a中提供了一种具有斑块孔像质计的替代方法，该方法涵盖了相同的焦点尺寸。 1.3 应使用测试方法测量较小的焦点 E2903 使用边的投影。 1.4 本试验方法也可用于确定由于管子老化、管子过载等原因可能发生的焦点尺寸变化。 这将需要制作焦点射线照片（采用针孔法）并评估产生的点蚀、裂纹等图像。 1.5 单位- 以国际单位制表示的数值应视为标准。 1.6 本标准并非旨在解决与其使用相关的所有安全问题（如有）。本标准的用户有责任在使用前制定适当的安全、健康和环境实践，并确定监管限制的适用性。 1.7 本国际标准是根据世界贸易组织技术性贸易壁垒（TBT）委员会发布的《关于制定国际标准、指南和建议的原则的决定》中确立的国际公认标准化原则制定的。 ====意义和用途====== 5.1 影响放射学图像质量的因素之一是几何不清晰度。 几何不清晰度的程度取决于辐射源的焦点大小、辐射源与待射线照相物体之间的距离，以及待射线照相物体与探测器（成像板、数字探测器阵列（DDA）或胶片）之间的距离。该测试方法允许用户确定X射线源的有效焦距。然后，该结果可用于确定源到目标和目标到探测器的距离，以保持给定射线成像应用所需的几何不锐度或最大放大率，或两者兼而有之。一些ASTM标准要求该值用于计算所需的放大倍数，例如实践 E1255 , E2033年 和 E2698 .

1.1 The image quality and the resolution of X-ray images are especially sensitive to the characteristics of the focal spot. The imaging qualities of the focal spot are based on its two dimensional intensity distribution as seen from the detector plane. 1.2 This test method provides instructions for determining the effective size (dimensions) of standard and mini focal spots of industrial X-ray tubes for focal spot dimensions from 100 μm up to several mm of X-ray sources up to 600 kV tube voltage. Smaller focal spots down to 50 µm could be evaluated with less precision. This determination is based on the measurement of an image of a focal spot that has been radiographically recorded with a “pinhole” technique. An alternative method with a plaque hole IQI may be found in the Annex A, which covers the same focal spot sizes. 1.3 Smaller focal spots should be measured using Test Method E2903 using the projection of an edge. 1.4 This test method may also be used to determine the change in focal spot size that may have occurred due to tube age, tube overloading, and the like. This would entail the production of a focal spot radiograph (with the pinhole method) and an evaluation of the resultant image for pitting, cracking, and the like. 1.5 Units— Values stated in SI units are to be regarded as the standard. 1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use. 1.7 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee. ====== Significance And Use ====== 5.1 One of the factors affecting the quality of radiologic images is the geometric unsharpness. The degree of geometric unsharpness is dependent on the focal spot size of the radiation source, the distance between the source and the object to be radiographed, and the distance between the object to be radiographed and the detector (imaging plate, Digital Detector Array (DDA) or film). This test method allows the user to determine the effective focal size of the X-ray source. This result may then be used to establish source to object and object to detector distances appropriate for maintaining the desired degree of geometric unsharpness or maximum magnification for a given radiographic imaging application, or both. Some ASTM standards require this value for calculation of a required magnification, for example, Practices E1255 , E2033 , and E2698 .