Radiographic Inspection of Thick Metal Components, Part I: Fitting the Standard Linear Image Formation Model

Radiography is an effective method for nondestructive inspection of thick metal components. However, although fully 3D reconstruction of defects would be a very valuable tool for the expert, it is not yet clear whether digitized radiographs are suitable for algebraic reconstruction. Based on a rigorous study of the radiographic image formation process, we show that it is indeed possible to process the raw data to closely fit the conventional line-integral projection model. In particular, we propose a novel field-flattening algorithm and a calibration method that requires minimal knowledge about the data acquisition parameters. The 3D reconstruction issue is addressed in a companion paper [Robini et al., 2006].