本标准规定了工业X射线计算机断层扫描（CT）系统对均质材料制成的基于球体的测试对象的长度、尺寸和形状测量的尺寸测量精度。医用CT系统不在本标准范围内。被测试验对象的材料特性仅限于三类选定的工业材料代表材料:塑料聚合物、铝合金和钢合金；其他材料不在本标准范围内。然而，本标准可作为测试其他材料CT系统性能的指南。由多种材料或具有密度梯度的材料组成的工件的评估，即材料内的逐渐密度变化，不在本标准的范围内。本标准适用于在工件表面进行的尺寸测量，即:。 e、 ，在工件材料-空气界面处，包括内腔。通过球体（用作计量几何元件）和障碍体组成的测试对象模拟复杂工件材料影响的效果；障碍物的尺寸未经校准，其形状可能是任意的。球体和阻挡体应为同一类材料，其组合长度不得超过CT系统制造商规定的该类材料的最大穿透长度。本标准适用于各种CT系统，这些系统可能因扫描模式和图像采集所涉及的系统组件而异。如果系统提供X射线源、探测器和扫描模式的多种配置，则可以为每个扫描模式指定尺寸测量精度。本标准不要求测试（由CT制造商或用户）来验证CT性能。 测试的数量，以及由哪一方承担测试成本，是一项商业决策，必须由双方协商确定。校准的测试对象可能很昂贵；因此，双方应确认相关成本，并相应地计划测试。由于X射线必须穿透大量材料时可能出现对比度灵敏度问题，本标准未提供适用于检测高空间频率形状误差的最大允许误差规范。

This Standard specifies the dimensional measurement accuracy of industrial X-ray computed tomography (CT) systems for length, size, and form measurands of sphere-based test objects made of homogeneous materials. Medical CT systems are outside the scope of this Standard. The material properties of the measured test objects are restricted to three classes of material selected to be representative of industrial materials: plastic polymers, aluminum alloys, and steel alloys; other materials are outside the scope of this Standard. However, this Standard may be used as a guide for testing the performance of a CT system for other materials. The evaluation of workpieces composed of multiple materials or of materials with density gradients, i.e., gradual density variations within the material, is outside the scope of this Standard.This Standard is applicable to dimensional measurements made at the surface of the workpiece, i.e., at the workpiece material–air interface, including those of internal cavities. The effect of complex workpiece-material influence is simulated by test objects composed of spheres (serving as the metrological geometric elements) and an obstructing body; the obstructing body's dimensions are uncalibrated and its shape may be arbitrary. The spheres and obstructing body shall be of the same class of material and their combined length shall not exceed the maximum penetration length for this class of material, as stated by the CT system manufacturer.This Standard applies to a variety of CT systems that may vary by scanning mode and system components involved in the acquisition of images. In cases where a system provides multiple configurations of X-ray sources, detectors, and scanning modes, the dimensional measurement accuracy may be specified for each scanning mode.This Standard does not mandate testing (by either the CT manufacturer or the user) to verify CT performance. The amount of testing, and which party will bear the cost of testing, is a business decision and must be negotiated between the two parties. Calibrated test objects can be expensive; hence, the parties should recognize the costs involved and plan the testing accordingly.Due to contrast sensitivity issues that can arise when X-rays must penetrate through large amounts of material, this Standard does not provide maximum permissible error specifications that apply to detecting high spatial-frequency form errors.