Abstract: A device for forming an X-ray beam or gamma beam (11) having a small cross-section and a variable direction, includes an X-ray source or gamma source (1) which supplies an X-ray beam and a diaphragm device which forms the X-ray beam from the radiation beam. The diaphragm device has a stationary diaphragm section (7) provided with a rectilinear slit (8) and a cylindrical first diaphragm body (3) which rotates about an axis of rotation (5) and which is provided with a helical slit (9) on its outer surface. In order to reduce the expenditure for manufacturing a device which is also suitable for different distances between the radiation source and the axis of rotation, the diaphragm body (3) has an at least approximately semi-circular cross-section over at least a part of its length.

Abstract: The invention relates to a method of determining the share of different chemical elements in a layer of an examination zone. The Compton scattered radiation and the Rayleigh scattered radiation are separately determined and the variation of the differential scatter coefficients derived from the measurement values is influenced by the shares of the various chemical elements contained in the individual pixels. Therefore, the share of these chemical elements can be determined therefrom.

Abstract: The invention relates to a method of determining the Compton profile of an object to be examined which is situated in an examination zone. The examination zone is irradiated by a monochromatic primary beam whose energy is chosen so that the attenuation of the primary radiation is due essentially only to the Compton Scattering. The scattered radiation is measured in an energy resolving manner and therefrom, as well as from the attenuation in the primary beam, the Compton profiles for the individual pixels in the examination zone are determined.

Abstract: A method and apparatus for measurement of an energy-independent attenuation factor in a predetermined area of a primary X-ray beam which passes through a test object. Two detectors measure scattered radiation on closely adjacent paths in each of two different spectral ranges. The attenuation factor is calculated from the difference of the logarithms of quotients of measurements taken at different engergies.

Abstract: The invention relates to a method for determination of the cross-sections for elastic scattered radiation in which a polychromatic radiation source is used but in which good differentiation between various substances is still possible.