Generation of Pictures by X-ray Scanners

The different generations of an X-ray scanner and their characteristics are outlined and the requirements for future developments are considered. The studies on the reconstruction of pictures in X-ray scanners concentrate on two problems: the picture quality and its restrictions due to physical and technical limitations of the scanning device and on new problems which may arise in future scanning devices. The accuracy of reconstructed absorption values and the spatial resolution are discussed in relation to quantum noise and sampling errors due to the limited number of sample points. The effect of erroneous detectors, the polychromatic nature of the X-ray source and patient motion is investigated. The results are illustrated by grey-level pictures.