ASME B89.4.23:2020 pdf free download

ASME B89.4.23:2020 pdf free download.X-Ray Computed Tomography (CT) Performance Evaluation.
NOTES:
(1) Rated operating conditions generally specify intervals of values for a quantity being measured and for any influence quantity.
(2) In this Standard. “as deslgned means “tO meet the specified MPE values’
(3) Conditions that are not explicitly constrained by the CT system manufacturer are acceptable conditions under which the system can be tested.
(4) In this Standard, “rated operating condition’ is also referred to as “rated condition”
(This definition, including Note (1), is identical to JCGM 200:2012, definition 4.9. Notes (2) through (4) are specific to this Standard.)
sphericity: spherical form.
NOTE: The sphericity of a test object may pertain to a portion of a sphere, e.g., a hemisphere.
voxe?: a unit in a three-dimensional (3D) array that discretizes a reconstructed work zone using the principle of computed tomography.
voxel size: the size of a magnified pixel for a CT scan, which is calculated as pixel size divided by magnification.
NOTES:
(1) Magnification is the X-ray source•to•detector distance divided by the X-ray source-to.obect distance.
(2) Other definitions of voxel size are possible. This definition Is common and chosen for convenience. It is expressed as a unit of length rather than volume. e.g.. in millimeters rather than in cubic millimeters.
work zone: a rated operating condition that is the boundary of the physical region within which measurements can be performed.
NOTE: In this Standard, the work zone may depend on the magnification used for the test.
5 EXAMPLES OF RATED OPERATING CONDITIONS
The rated operatingconditions are stated by the CT system manufacturer and represent the conditions for which the CT system has MPE values. Although a CT system may be capable of obtaining measurements outside its rated operating conditions, the user cannot be sure of the accuracy of such measurements. The rated conditions make up the applicable domain where measurements can be accurately obtained. Consequently, when selecting a CT system, users should review all the rated operating conditions and especially the rated material classes and their maximum penetration lengths. lithe largest penetration length of a workpiece. in any radiograph, exceeds the maximum penetration length (stated by the CT system manufacturer) for that material class, then that measurement is outside the rated operating conditions of the CT system. Since material effects are a major source of error in CT measurements, the user should ensure that the accuracy of the CT system is sufficient at the largest penetration length of any workpiece measurement anticipated and should also test the system at this condition. Any condition that is specified by the CT system manufacturer for the proper operation of the system is a rated condition — this includes requirements described in the operating manual. Paragraphs 5.1 through 5.7 list examples of rated operating conditions.