【国外标准】 Standard Practice for Cone Beam Computed Tomographic (CT) Examination

4.1 The purpose of this practice is to establish instruction, procedures, and equipment qualification to inspect a component for specified discontinuities. This practice is written so it can be specified on the engineering drawing, specification, or contract. This practice requires a detailed procedure delineating the technique or procedure requirements and shall be approved by the Cognizant Engineering Organization (CEO).4.2 The requirements in this practice shall be used when placing a CT system into NDT service and establishing a baseline of system performance measures. Monitoring the system performance over time shall be performed, including detector correction procedures, performance measurements, and system maintenance.4.3 For CT examinations where specified discontinuities are not known/identified/requested/available (that is, engineering analysis, engineering information only), portions of Section 7 – 9 requirements do not necessarily apply. For these types of examinations, the purchase order or contract shall specify the development of a specific procedure, approved by purchaser and supplier, to specify the requirements of this practice to be incorporated into the examination.1.1 This practice establishes the minimum requirements for computed tomography (CT) examination of components using cone beam systems. The purpose of this practice is to establish instruction, procedures, and equipment qualification to inspect a component for specified discontinuities.1.2 This practice applies to systems with a Digital Detector Array (DDA) and an X-ray source. It does not cover the use of isotope sources.1.3 There are sections in this practice that may require agreement between the purchaser and the supplier, or specific direction from the cognizant engineering organization (CEO). These items should be addressed in the purchase order or the contract. Generally, the items are application-specific, performance related, or both.1.4 Applications for cone-beam CT are diverse. This practice is not intended to be limiting or restrictive. Refer to Guide E1441 for guidance on CT fundamentals and Guide E1672 for tradeoffs in selection of a CT system.1.5 Units—The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.1.6 This standard does not purport to address all of the safety concerns 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. NCRP 144 or NIST Handbook 114, or both, may be used as guides to ensure that radiographic procedures are performed so that personnel shall not receive a radiation dosage exceeding the maximum permitted by the city, state, or national codes.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.