Abstract: In therapeutic radiographic apparatus it is desirable to maintain the penetrating radiation in passing through tissue to be irradiated, rather than surrounding healthy tissue, despite movements of the patient. A shadowgraph radiographic picture of part of the patient is obtained by derivation from cross-sectional radiographic pictures from computerized axial tomography (CAT) apparatus. A similar shadowgraph picture is obtained, during therapy treatment, by collecting the therapy radiation after passing through the body. The two pictures are compared to determine the position of the therapy radiation relative to the tissue to be irradiated and the position is adjusted in response to the comparison.

Abstract: In a scanning radiographic apparatus, of a type which is particularly suitable for examining inanimate objects, a fixed source and detectors irradiate an object to be examined along a plurality of beam paths. The object is moved in relation to the source and detectors to direct the radiation along a sufficient number of beam paths to allow suitable processing. The object is, for that purpose, mounted on a turntable which can also execute a reciprocating lateral motion relative to the source and detectors.

Abstract: A computerized tomographic apparatus is disclosed, as well as a method of operating such apparatus. In circumstances where collimation between the body under examination and the radiation-sensitive detector means is difficult to apply, errors in evaluated absorption coefficients for locations distributed over a cross-sectional slice of the body due to scatter within the slice are reduced by producing a first estimate of the distribution of said absorption coefficients, using this estimate to obtain an indication of the amount of scatter likely to arise from the various locations when irradiated along different paths and using such indication to effect scatter compensation.

Abstract: In an apparatus for examining a body with penetrating radiation a source and detector arrangement scan about the body to irradiate the body along a plurality of beam paths lying in a plane. Output signals are provided from weighted components where each component relates to the absorption of the radiation along one of a set of adjacent and substantially parallel beam paths. The weighting is according to a function chosen so that the output signals are restricted to a chosen spatial frequency band to reduce errors in a representation, if the distribution of absorption of the radiation through the body, constructed from the output signals. The weighting may be provided by optical means between scintillator crystals and photomultipliers forming the detector arrangement.