【国外标准】 Standard Practice for Determining Image Unsharpness and Basic Spatial Resolution in Radiography and Radioscopy

5.1 The gauge is intended to provide a means for measuring image or detector unsharpness and basic spatial resolution of the image or detector as independently as practicable from the imaging system and contrast sensitivity limitations. When the duplex gauge is positioned directly on the film or the digital detector and not on the test object, then the determined unsharpness corresponds to the inherent film or detector unsharpness (Udetector) and the determined basic spatial resolution corresponds to the basic spatial detector resolution SRbdetector.NOTE 1: The gauge, described in ISO 19232-5, is equivalent to this standard in the dimensions and the evaluation procedure.5.2 Basis of Application 5.2.1 The following items are subject to contractual agreement between the parties using or referencing this practice.5.2.1.1 Personnel Qualification—Personnel performing examinations to this practice shall be qualified in accordance with NAS410, EN 4179, ANSI/ASNT CP 189, ISO 9712, or SNT-TC-1A and certified by the employer or certifying agency as applicable. Other equivalent qualification documents may be used when specified on the contract or purchase order. The applicable revision shall be the latest unless otherwise specified in the contractual agreement between parties.5.2.1.2 If specified in the contractual agreement, NDT agencies shall be qualified and evaluated as described in Specification E543. The applicable edition of Specification E543 shall be specified in the contract.1.1 This practice covers the design and basic use of a gauge used to determine the image unsharpness and the basic spatial resolution of film radiographs or of digital images taken with CR imaging plates, digital detector arrays, or radioscopic systems.1.2 This practice is applicable to radiographic and radioscopic imaging systems utilizing X-ray and gamma ray radiation sources.1.3 Units—The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.1.4 The gauge described can be used effectively with tube voltages up to 600 kV.1.5 When using source voltages in the megavolt range, the results may not be completely satisfactory. The gauge may be used in the MV range, preferably for characterization of detectors without object.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.