Patent ID: 6744846
Filing Date: 2004-06-01
Classification: A61B,H05G

Abstract:
A computed tomography apparatus comprising:an X-ray source which emits an X-ray beam from a focus, said X-ray source having at least one operating parameter which determines a radiation dose associated with said X-ray beam; a radiation detector on which said X-ray beam is incident, said X-ray source and said radiation detector being adapted to receive a subject therebetween so that said X-ray beam is incident on said radiation detector after being attenuated by said subject, said radiation detector generating electrical signals dependent on X-rays incident thereon; at least said focus being rotatable through at least one revolution around said subject to conduct a CT scan wherein said electrical signals form projection data for a slice of said subject; a computer supplied with said projection data for reconstructing an image of said slice therefrom; and a control arrangement connected to said radiation detector and to said X-ray source for, during a first half of said revolution, calculating an actual attenuation profile of said slice from said electrical signals generated in said first half of said revolution and for calculating an extrapolated attenuation profile of said slice for a second half of said revolution from said actual attenuation profile, and for adjusting said at least one operating parameter to modify said radiation dose during said second half of said revolution dependent on said extrapolated attenuation profile.