Patent ID: 6862336

Claim:
An X-ray CT apparatus comprising: a gantry having an X-ray tube for emitting X-rays and a detector for detecting the X-rays emitted by said X-ray tube, said gantry outputting projection data D 0 corresponding to an amount of the X-rays detected by said detector, represented by a view angle and a channel of said detector; an operating console having an axially projected data/pixel projection data calculating device for determining axially projected data D 1 by projecting said projection data D 0 obtained by said gantry onto a reference axis in a reconstruction region, and further determining pixel projection data D 2 by projecting said axially projected data D 1 onto coordinates of pixels constituting said reconstruction region, said operating console determining backprojection data D 3 by adding said pixel projection data D 2 determined by said axially projected data/pixel projection data calculating device for all views used in image reconstruction; an amount-of-offset measuring device for obtaining information indicative of an amount of offset of the position of said X-ray tube from a prespecified position; and a correcting device for correcting the axially projected data D 1 or pixel projection data D 2 determined by said axially projected data/pixel projection data calculating device using the information indicative of the amount of offset obtained by said amount-of-offset measuring device.