Performance Testing of Computed Radiography System and Imaging Plates

摘要

Industrial radiography is a very mature non-destructive testing (NDT) technique for volumetric investigation. It provides high throughput in inspection particularly for aircraft structural components and, therefore, an important NDT tool for aircraft structural maintenance. Use of film for NDT applications is gradually diminishing because of time, increased cost, and the lack of digital advantages. Industrial radiography community is making an intense effort to replace the conventional film technique with digital technologies (e.g., computed radiography or CR) which allow faster/easier image acquisition digitally. Despite numerous benefits when compared to conventional film-based radiography, its widespread application still poses significant challenges (e.g. cost, steep learning curve, lack of procedures to choose parameters, lack of demonstrated system performance, imaging artifacts, etc.). Before replacing film-based radiography with CR, performance assessment of the new technology is required to determine if the current CR technology can effectively provide equal or better performance than the existing film-based technology. This paper highlights the existing CR qualification practices, lessons learned and key issues faced while performing experimental validation for qualification of a computed radiography system in accordance with ASTM E2445 standard. The major CR system quality parameters such as spatial resolution, contrast sensitivity, contrast-to-noise ratio (CNR), signal-to-noise ratio (SNR), as well as other system hardware integrity parameters were measured as part of qualification process and assessment of suitability of CR for aerospace applications.