Digital radiography: description and user's guide

The presented document arises from the work of the group 'Digital Radiography and sensors' of COFREND. It is a collective work of synthesis aimed to analyze the quality parameters of digital images influencing the answer and the diagnosis brought to a given industrial problem. Five families of digital sensors have been studied: 1. Image Intensifier coupled with CCD devices - 2. scintillators coupled with a CCD device- 3. Flat Panels with indirect conversion - 4. Flat Panels with direct electric conversion - 5. Photostimulable Storage Phosphor Screens). In particular, concerning a complete imaging chain, it deals with the notions of magnification, blur (unsharpness) (geometrical, kinetic or internal to the very sensor), noises, scattered radiation, spatial resolution, which is different from the one of analog detectors such as films, Contrast to Noise Ratio (CNR), sensitivity using IQIs, dynamic range, detection quantum efficiency, persistence and temporal resolution. This document is not a standard; it must be understood as a user's guide, and it approaches some essentials corrections to bring to a sensor in order to optimize his efficiency without losing information during the pre-processing phase in the radiographic acquisition. It also introduces some image processing tools commonly used. It can be used as a source document to the future elaboration of a standardisation document. It augurs not at all of the choice of a digital sensor with regard to the traditional radiographic film, but gives bases of reflection to a radio user for a sensible transfer from the classic radiography to the digital radiography. (authors)