Patent ID: 6385280
Filing Date: 2002-05-07
Classification: A61B,H05G

Abstract:
An x-ray computed tomography apparatus comprising:an x-ray source which emits an x-ray beam, said x-ray beam being displaceable relative to an examination subject having an attenuation profile, to irradiate said examination subject from a plurality of different positions, said x-ray beam having an x-ray power associated therewith; a radiation detector on which said x-ray beam is incident, said detector producing measurement data dependent on attenuation of said x-ray beam by said subject for a plurality of projections corresponding to respectively different positions of said x-ray beam; a pulsing arrangement in communication with said x-ray source to cause said x-ray beam to be emitted in at least one pulse of x-rays during acquisition of the measurement data for each projection; and a modulation arrangement for modulating the x-ray power by setting a duration of said at least one pulse dependent on said attenuation profile during each projection to produce an mAs product to achieve a selected signal-to-noise ratio in each projection and so that an average of said mAs product substantially corresponds to said attenuation profile in each projection.