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

5.1 The gauge is intended to provide a means for measuring image or detector unsharpness and basic spatial image or detector resolution as independently as practicable from the imaging system and contrast sensitivity limitations. When the duplex plate gauge is positioned directly on the film or the digital detector instead on the test object, then the determined image unsharpness UIm corresponds to the inherent film or detector unsharpness (Udetector) and the determined basic spatial image resolution SRbimage corresponds to the basic spatial detector resolution SRbdetector. SRbimage provides a value which depends on the combined effect of detector unsharpness and geometric unsharpness.5.2 Basis of Application: 5.2.1 The following items are subject to contractual agreement between the parties using or referencing this standard.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 (DDA), or radioscopic systems (for example, with X-ray image intensifiers) for applications with Se-75, Ir-192, Co-60 and high energy sources with tube potentials ≥ 300 kV. The IQI may be used at lower tube potentials too, if the expected unsharpness is > 200 µm (SRbimage or SRbdetector > 100 µm). For the measurement of lower unsharpness values, the usage of the gauge described in Practice E2002 is recommended.1.2 This practice is applicable to radiographic and radioscopic imaging systems utilizing X-ray and gamma ray radiation sources.1.3 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 if the duplex wire IQI of Practice E2002 does not provide sufficient contrast resolution.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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.1.6 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.