Patent ID: 7076019

Claim:
A radiation computed tomography apparatus comprising: a radiation source for emitting radiation toward a subject; an adjusting device for adjusting an emission extent of the radiation from said radiation source in response to a control command; a detector array forming a two-dimensional radiation detection surface comprised of a plurality of radiation detectors, for detecting the radiation on said radiation detection surface; a reconstructing device for calculating and reconstructing tomographic image data for a tomographic image of said subject based on projection data of said subject by the radiation acquired by said detector array; and a control device for calculating an irradiated region in said radiation detection surface required for acquiring said projection data for use in reconstruction of a certain portion of said tomographic image data based on parameters relating to reconstruction of said tomographic image data by said reconstructing device, and outputting control command to said adjusting device for emitting the radiation to impinge upon said irradiated region, wherein said control device configured to calculate the irradiation region by selecting a subset from a set of rows of said radiation detectors, and said control device configured to select the subset based on the parameters including a helical pitch of a helical scan.