1.1 该测试方法为确定X射线和γ射线计算机断层扫描（CT）体积中的空间分辨率和对比灵敏度提供了指导。该测定基于对均匀材料圆柱体CT体积的检查。空间分辨率测量（调制传递函数）是通过对重建圆柱切片边缘锐度的图像分析得出的。对比度灵敏度测量（对比度判别函数）来自对圆柱体切片中心的对比度和统计噪声的图像分析。 1.2 与替代方法相比，该测试方法更定量，更不容易解释，因为所需的圆柱体易于制造，分析也易于执行。 1.3 该测试方法不是为了预测特定应用中特定物体特征或缺陷的可检测性。这是IQI和RQI标准和标准实践的主题。 1.4 该方法测试并描述了CT系统的整体性能。系统组件（如X射线管、伽马源和探测器）的性能测试由单独的文件（即指南）涵盖 E1000 实践 E2737 ，并练习 2002年 ; c、 f。 2.1 ，进一步系统分析时应参考。 1.5 单位- 以国际单位制表示的数值应视为标准值。国际单位制后括号中给出的值仅供参考，不被视为标准值。 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====== 4.1 影响CT图像质量的主要因素是图像总不清晰度( U T 形象 )、对比度（Δµ）和随机噪声（σ）。几何和探测器的不清晰度限制了CT系统的空间分辨率，即其对物体中精细结构细节的成像能力。 随机噪声和对比度响应限制了CT系统的对比度灵敏度，即其检测物体中是否存在特征的能力。空间分辨率和对比灵敏度可以通过各种方式测量。在该测试方法中，空间分辨率根据调制传递函数（MTF）进行量化，对比度灵敏度根据对比度判别函数（CDF）进行量化。对比度灵敏度和描述分辨率和检测能力的空间分辨率之间的关系由对比度细节图（CDD度量，另请参阅指南）给出 E1441 和实践 E1570 ). 该测试方法允许CT系统或服务的买方或供应商，或两者，测量和指定空间分辨率和对比灵敏度，是测量系统随时间变化的稳定性和性能可接受性的一种方法。

1.1 This test method provides instruction for determining the spatial resolution and contrast sensitivity in X-ray and γ-ray computed tomography (CT) volumes. The determination is based on examination of the CT volume of a uniform cylinder of material. The spatial resolution measurement (Modulation Transfer Function) is derived from an image analysis of the sharpness at the edges of the reconstructed cylinder slices. The contrast sensitivity measurement (Contrast Discrimination Function) is derived from an image analysis of the contrast and the statistical noise at the center of the cylinder slices. 1.2 This test method is more quantitative and less susceptible to interpretation than alternative approaches because the required cylinder is easy to fabricate and the analysis easy to perform. 1.3 This test method is not to predict the detectability of specific object features or flaws in a specific application. This is subject of IQI and RQI standards and standard practices. 1.4 This method tests and describes overall CT system performance. Performance tests of systems components such as X-ray tubes, gamma sources, and detectors are covered by separate documents, namely Guide E1000 , Practice E2737 , and Practice E2002 ; c.f. 2.1 , which should be consulted for further system analysis. 1.5 Units— The values stated in SI units are to be regarded as standard. The values given in parentheses after SI units are provided for information only and are not considered 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 ====== 4.1 The major factors affecting the quality of a CT image are total image unsharpness ( U T image ), contrast (Δµ), and random noise (σ). Geometrical and detector unsharpness limit the spatial resolution of a CT system, that is, its ability to image fine structural detail in an object. Random noise and contrast response limit the contrast sensitivity of a CT system, that is, its ability to detect the presence or absence of features in an object. Spatial resolution and contrast sensitivity may be measured in various ways. In this test method, spatial resolution is quantified in terms of the modulation transfer function (MTF), and contrast sensitivity is quantified in terms of the contrast discrimination function (CDF). The relationship between contrast sensitivity and spatial resolution describing the resolving and detecting capabilities is given by the contrast-detail-diagram (CDD metric, see also Guide E1441 and Practice E1570 ). This test method allows the purchaser or the provider of CT systems or services, or both, to measure and specify spatial resolution and contrast sensitivity and is a measure for system stability over time and performance acceptability.