Abstract: A method and apparatus for positioning a patient arranged on the top of a patient table wherein two X-ray images are formed from different perspectives after which they are stored. After the first X-ray image, the table top is displaced in two mutually perpendicular directions and a marker which is electronically superposed on the X-ray image on a monitor is also shifted until it is situated in the region in the X-ray image which is to be positioned. After a second X-ray exposure this operation is repeated. The shift of the marker in the different directions on the monitor or the displacement of the table top in the three spatial directions are not mutually independent but are derived from the value obtained at the end of the first positioning operation.

Abstract: The invention relates to diaphragm means arranged close to the film in an X-ray spot film device. The diaphragm means comprises a first diaphragm with several rectangular aperture sections. The sections are displaced in the horizontal direction and have different vertical dimensions. A second diaphragm assembly has vertically extending diaphragm edges. By moving the first diaphragm to different positions in the radiation path, the aperture can be adapted to exposure formats of different vertical dimensions.

Abstract: The invention relates to an X-ray spot-film device comprising two sliding-fixtures. The sliding-fixtures serve inter alia, for the measurement of a film cassette. The measurement of the dimensions of the cassette is performed by means of a single strap which is coupled to the sliding fixtures. The effect of the cassette height on a measurable dimension of the strap differs from the effect of the cassette width. Consequently, the measurement also determines whether the cassette has been inserted upright or sideways.