Patent ID: 6999551

Claim:
A method for operating a computed tomography apparatus comprising the steps of: disposing an examination subject between an x-ray source and a multi-line radiation detector having at least two parallel lines of image detectors; emitting x-rays from said x-ray source and limiting said x-rays with a diaphragm to form a fan-shaped x-ray beam; irradiating said examination subject with said fan-shaped x-ray beam while rotating said x-ray source and said radiation detector around a system axis, said examination subject occluding only a portion of said fan-shaped beam from said radiation detector; obtaining image information from said radiation detector dependent on said fan-shaped beam incident thereon; in a computer system, calculating an intensity distribution from said image information; identifying regions of said radiation detector that are not occluded by said examination subject by comparing said intensity distribution to a threshold and identifying said regions where said threshold is exceeded; and employing only image information from said regions of said radiation detector that are not occluded by said examination subject for regulating a position of said diaphragm.