1.1 CT是一种射线照相检查技术，可生成物体三维数字图像，包括内部结构。由于X射线具有相对良好的穿透性，CT允许对材料的内部结构进行非破坏性的物理表征，并在一定程度上进行化学表征。此外，由于该方法基于X射线，因此同样适用于金属和非金属试样、固体和纤维材料以及光滑和不规则表面的物体。 1.2 本指南旨在满足工业CT设备用户的两个一般需求:（1）需要一个介绍X射线成像一般原理的教程指南- 应用于工业成像的射线CT；（2）需要一套一致的CT性能参数定义，包括这些性能参数与CT系统规范的关系。 1.3 本指南未规定CT检查技术，例如扫描参数的最佳选择、扫描程序的首选实施，或为新物体建立接受/拒绝标准。 1.4 单位- 本文件中未提及任何单位。然而，对于CT，数值通常以国际单位制表示，并被视为标准值。 1.5 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。 1.6 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 计算机断层扫描（CT）是一种射线照相重建方法，当主要目标是在三维中定位和确定平面和体积细节时，它提供了一种敏感的技术。 5.2 CT通过计算机提供作为密度和元素数（衰减系数）函数的定量体积图像- 从不同角度采集的多个X射线测量值的处理组合，以生成扫描对象特定区域的横截面图像，使用户无需切割即可看到对象内部。由于消除了重叠结构，CT被认为比传统的射线照相数据更容易解释。新用户可以快速学习读取CT数据，因为与传统的投影射线照相相比，这些图像更接近人类思维可视化三维结构的方式。此外，由于CT切片和体积是数字的，因此与其他无损检测模式的数字数据相比，可以对其进行增强、分析、压缩、归档，将其作为数据输入性能计算，或者传输到其他位置进行远程查看。

1.1 CT is a radiographic examination technique that generates digital images in three dimensions of an object, including the interior structure. Because of the relatively good penetrability of X-rays, CT permits the nondestructive physical and, to a limited extent, chemical characterization of the internal structure of materials. Also, since the method is X-ray based, it applies equally well to metallic and non-metallic specimens, solid and fibrous materials, and smooth and irregularly surfaced objects. 1.2 This guide is intended to satisfy two general needs for users of industrial CT equipment: (1) the need for a tutorial guide addressing the general principles of X-ray CT as they apply to industrial imaging; and (2) the need for a consistent set of CT performance parameter definitions, including how these performance parameters relate to CT system specifications. 1.3 This guide does not specify CT examination techniques, such as the best selection of scan parameters, the preferred implementation of scan procedures, or the establishment of accept/reject criteria for a new object. 1.4 Units— No units are mentioned in this document. However, for CT, values are typically stated in SI units and are regarded as standard. 1.5 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. 1.6 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 Computed tomography (CT) is a radiographic reconstruction method that provides a sensitive technique whenever the primary goal is to locate and size planar and volumetric detail in three dimensions. 5.2 CT provides quantitative volume images as a function of density and element number (attenuation coefficient) by means of computer-processed combinations of many X-ray measurements taken from different angles to produce cross-sectional images of specific areas of a scanned object, allowing the user to see inside the object without cutting. CT is considered much easier to interpret than conventional radiographic data due to the elimination of overlapping structures. The new user can learn quickly to read CT data because the images correspond more closely to the way the human mind visualizes three-dimensional structures than conventional projection radiography. Further, because CT slices and volumes are digital, they may be enhanced, analyzed, compressed, archived, input as data into performance calculations, compared with digital data from other NDE modalities, or transmitted to other locations for remote viewing.