Significance and Use
This practice is applicable for the systematic assessment of the internal structure of a material or assembly using CT technology. This practice may be used for review by system operators, or to prescribe operating procedures for new or routine test objects.
This practice provides the basis for the formation of a program for quality control and its continuation through calibration, standardization, reference samples, inspection plans, and procedures.
1.1 This practice is for computed tomography (CT), which may be used to nondestructively disclose physical features or anomalies within a test object by providing radiological density and geometric measurements. This practice implicitly assumes the use of penetrating radiation, specifically X-ray and γ-ray.
1.2 CT systems utilize a set of transmission measurements made along paths through the test object from many different directions. Each of the transmission measurements is digitized and stored in a computer, where they are subsequently reconstructed by one of a variety of techniques. A treatment of CT principles is given in Guide E1441.
1.3 CT is broadly applicable to any material or test object through which a beam of penetrating radiation passes. The principal advantage of CT is that it provides densitometric (that is, radiological density and geometry) images of thin cross sections through an object without the structural superposition in projection radiography.
1.4 This practice describes procedures for performing CT examinations. This practice is to address the general use of CT technology and thereby facilitate its use.
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 and health practices and determine the applicability of regulatory limitations prior to use. For specific safety statements, see Section 8, NBS Handbook 114, and Federal Standards 21 CFR 1020.40 and 29 CFR 1910.96.
2. Referenced Documents (purchase separately) The documents listed below are referenced within the subject standard but are not provided as part of the standard.
E1316 Terminology for Nondestructive Examinations
E1441 Guide for Computed Tomography (CT) Imaging
E1695 Test Method for Measurement of Computed Tomography (CT) System Performance
ANSIN43.3 General Radiation Safety Installations Using Non-Medical X-Ray and Sealed Gamma Sources up to 10 MeV Available from National Institute of Standards and Technology (NIST), 100 Bureau Dr., Stop 1070, Gaithersburg, MD 20899-1070, http://www.nist.gov.
artifact; beam-hardening; computed tomography; contrast; contrast detail dose curves; contrast sensitivity; data storage; densitometric images; detection system; edge response function; field-of-view; gamma-ray; image analysis; image display; image reconstruction; line pairs/millimetre; line spread function; linear attenuation; manipulation system; modular transfer function; noise; pixel ; reconstruction diameter; reconstruction matrix; signal-to-noise; slice plane thickness; spatial resolution; system configuration; test object; test phantom; voxel; X-ray; Artifacts; Ceramic materials/applications; Composites; Computed tomography (CT); Contrast detail dose curves; Densitometric images; Edge response function; Field-of-view; Image analysis; Linear attenuation; Line spread function; Metallurgical structure; Modular transfer function (MTF); Nonmetallic composite material; Reconstruction diameter; Signal-to-noise ratio; Spatial resolution; Tomography
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