X-ray apparatus especially for mammography

Abstract

An X-ray machine, especially for mammography, includes an X-ray source and a suitable table or support for the object to be examined. The table is transparent to X-rays and holds sheets of X-ray film or the like to record the transmitted radiation. In addition to a fixed diaphragm which defines a substantially pyramidal primary beam, there are provided three sets of beam-defining slits, one behind the fixed diaphragm, one ahead of the object of examination and one just ahead of the recording medium. These three slits are disposed in geometrical similarity, i.e., their free width increases in proportion to their distance from the source. Furthermore, each of these slits is movable in a plane normal to the main axis of the primary beam. The three slits together define a narrow angular portion of the primary beam and their motion is so coordinated that the narrow beam is scanned across the object from one extreme position to the other. The successive slits reduce or eliminate the effects of blurring due to the finiteness of the sources and also pervent scattered radiation from the air or from the object of examination to reach the film.