Abstract: A computer tomography device in which the detectors are asymmetrically arranged with respect to the connecting line between the X-ray source, the center of rotation of the source, and the detectors, produce. The detector device produces an incomplete profile of measuring values which are supplemented with "zeros" during processing in order to form a number of measuring values of a complete profile. In order to avoid artefacts which are produced by the acute transients between measuring values and "zeros", a number of measuring values adjoining the acute transients are projected around the center of rotation and multipled by a factor so that from the zeros a smoothly increasing series of adapted measuring values is obtained.

Abstract: For the backprojection of the convoluted measurement signals in a cartesian coordinate system in a computer tomography device, it is necessary to recalculate the weighting factors for each position of the source in order to determine the contribution of a convoluted measurement signal to the attenuation value associated with a given element of the output image matrix. This is a time consuming and hence expensive form of reconstruction, and can be avoided by storing all the weighting factors required; this, however, implies a very large memory, and is also expensive.The invention relates to the use of a matrix of elements organised in polar coordinates, which is stored in the memory, the origin central coordinate of said matrix coinciding with the center of rotation of the X-ray source about the object section. The weighting factors are also stored in a polar organized memory.