Patent ID: 7274770

Claim:
An X-ray examination apparatus ( 1 ) comprising: a controllable X-ray source ( 1 c ) arranged to generate an X-ray beam ( 1 f ); an X-ray detector ( 1 d ) arranged to produce a first image upon an interception of the X-ray beam ( 1 f ); image processing means ( 3 ) arranged to process at least a part of the first image with a grey-level compression function ( 3 a ) in order to compress the first image into a second image; control means ( 6 ) arranged to compute an average grey value of pixels of the second image and to provide a dose control signal (C) to the X-ray source ( 1 c ) in order to control the X-ray beam ( 1 f ), the dose control signal (C) being determined from a comparison between the computed average grey level value and a pre-stored reference value (CA).