17th World Conference on Nondestructive Testing, 25-28 Oct 2008, Shanghai, China Strategies for Film Replacement in Radiography - Films and Digital Detectors in Comparison - Uwe EWERT 1 , Uwe ZSCHERPEL 1 , Klaus BAVENDIEK 2 , 1 Institute for Materials Research and Testing (BAM), D-12200 Berlin, Germany; Phone: +49 30 8104 1830, Fax: +49 30 8104 18 37; E-mail: uwe.ewert@bam.de , uwe.zscherpel@bam.de , 2 YXLON International GmbH, D-22419 Hamburg, Germany E-mail: klaus.bavendiek@hbg.yxlon.com Abstract The NDT community has discussed about effective film replacement by Computed Radiography (CR) and the new Digital Detector Arrays (DDA), also known as flat panel detectors, since more than 10 years. Several standards were published by CEN, ASTM and ASME to support the application of phosphor imaging plates in lieu of X-ray film in the year 2005. One of the key concepts is the usage of signal/noise (SNR) measurements as equivalent to the optical density of film and film system class. The radiographic practice with DDAs is not yet described by any standard, but proposals are under discussion. The first qualification standard for DDAs, ASTM E 2597-07, has been published recently. The bad pixel problem has been addressed. Measurement methods were elaborated and tested at BAM for determination of parameters as basic spatial resolution, efficiency, specific material thickness range, contrast sensitivity and image lag. These procedures were used for this study. The achieved image quality is discussed for film replacement by CR and DDAs in weld inspection. New strategies for correct DDA calibration yield an extra ordinary increase of image quality. The contrast sensitivity was enhanced up to 10 times in relation to film radiography. This could not yet be achieved by any other technology. Even restrictions in the spatial resolution, provoked by the individual picture element (pixel) size of the detector, are compensated by the increased contrast sensitivity. Keywords: radiography, film replacement, computed radiography, imaging plates, digital detector arrays, contrast sensitivity, SNR, standards 1 Introduction For more than 100 years industrial radiology has been based on X-ray film. Special film systems have been developed for NDT applications, which have better image quality than medical film systems but lower speed. High spatial resolution is obtained by combination of these films with lead screens instead of fluorescent screens. Computed Radiography (CR) and Digital Detectors Array (DDA) systems were developed for medical applications, which have the potential to replace the X-ray film and revolutionize the radiological technique. These detectors enable new computer based applications with new intelligent computer based evaluation methods. These technological and algorithmic developments are also applicable to new NDT procedures.