Patent ID: 8031834

Claim:
A tomosynthesis apparatus comprising: an x-ray source that emits an x-ray beam from a focus, said x-ray beam having a central beam axis; a flat panel detector that is irradiated by said x-ray beam and that generates a detector output signal dependent on radiation incident on said flat panel detector, said flat panel detector having an active detector area having flat panel detector dimensions, said x-ray source and said flat panel detector are adapted to receive a patient therebetween; said focus being movable in a scan direction relative to said flat panel detector to set a tomosynthesis angle at which said central beam axis is incident on said flat panel detector, said focus being movable through a plurality of different tomosynthesis angles to irradiate said flat panel detector respectively from different directions for which respective projection data sets are generated at the output of said flat panel detector; a collimator diaphragm located in a path of said x-ray beam between said focus and said flat panel detector, said collimator diaphragm having a diaphragm aperture that limits a size and shape of said x-ray beam, said diaphragm aperture being adjustable in size and shape; said collimator diaphragm comprising two side lamellae, respectively located at and defining opposite sides of said diaphragm aperture, said two side lamellae each being oriented substantially perpendicularly to said scan direction and having a spacing from said central beam axis that is adjustable by said control unit substantially parallel to said scan direction dependent on said tomosynthesis angle; said collimator diaphragm comprising a fixed lamella that is located at and defines a side of said diaphragm aperture facing toward the patient, said fixed lamella having a spacing from said central beam axis that is constant as said tomosynthesis angle changes, said side lamellae each being disposed at an angle of 90° relative to said fixed lamella; said collimator diaphragm comprising a rotating lamella mounted in said collimator diaphragm to rotate in a plane of said diaphragm aperture, said rotating lamella being rotated by said control unit to limit said diaphragm aperture at a side thereof facing away from the patient; a control unit connected to said collimator diaphragm that dynamically adjusts the size and shape of said diaphragm aperture dependent on the changing tomosynthesis angle to always cause an area of said x-ray beam that irradiates said flat panel detector to substantially correspond to said flat panel detector dimensions; and a tomosynthesis image reconstruction computer supplied with said projection data sets from said flat panel detector, configured to execute an image reconstruction algorithm to reconstruct a three-dimensional tomosynthesis image from said projection data sets, said tomosynthesis image reconstruction computer making said three-dimensional tomosynthesis image available at an output thereof.