ASTM E3505-25

1.1 This practice provides instructions for determining the detail detection sensitivity (DDS) and its numerical limit (DDS_Limit) in slices of X-ray computed tomography (CT) volumes.

1.2 This practice does not intend to predict the detectability of specific object features or discontinuities in a specific application. Representative quality indicators (RQIs, Practice E1817), standard practices, and studies for probability of detection (Practices E2862 and E3023) should be considered for qualifying individual applications (see Guide E3327 and Practice E3375).

1.3 This practice describes the overall CT detail detection sensitivity (DDS) in an idealized object. Performance tests of system components such as X-ray tubes, gamma sources, and detectors are covered by separate documents (see Guide E1000, Test Method E1165, Practice E2597, Practice E2737, Test Method E2903) and should be considered for further system analysis.

1.4 This practice does not exclude other hole arrangements approved by the CEO. In such cases, the below analysis and interpretation might not be applicable, and the analysis should be described in a specific document approved by the CEO.

1.5 The values stated in SI units are to be regarded as the standard. Inch-pound units are provided for information only.

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.

5.1 This practice provides instructions for determining the detail detection sensitivity (DDS) and its numerical limit, DDS_Limit, in X-ray computed tomography (CT) volumes from disk IQIs. DDS, along with modulation transfer function (MTF), contrast discrimination function (CDF), and contrast-detail-diagram (CDD), provides a way to determine the image quality in a reconstructed CT slice. See Test Method E1695 for a detailed description to measure and numerically evaluate MTF and CDF, and to document the result. See Guide E1441 for a detailed description of CDD.

5.2 DDS, along with Test Method E1695 MTF and CDF, and the derived DDS_Limit enable evaluation of the performance and image quality of CT systems at the CT settings selected for the examination. These values are used to verify CT system performance and monitor long-term stability of CT systems related to the CT settings.