X-RAY EXAMINATION APPARATUS WITH EXPOSURE CONTROL

摘要

An X-ray examination apparatus includes an X-ray source, an X-ray detector and an exposure control system. The exposure control system is arranged to control the X-ray source so as to perform a test exposure at a low X-ray dose and to perform an X-ray exposure at a higher X-ray dose. The X-ray detector applies a control signal resulting from the test exposure to the exposure control system and the X-ray source is adjusted on the basis of this control signal. The X-ray exposure produces an X-ray image and the X-ray detector supplies an image signal representing this X-ray image. The exposure control system is arranged to adjust the X-ray detector to a low spatial resolution during the test exposure and to a high spatial resolution during the X-ray exposure. The X-ray detector preferably includes a sensor matrix having sensor elements arranged in columns and rows. The spatial resolution is adjusted by deriving the control signal and the image signal from large and small groups of sensor elements, respectively.