X-ray CT apparatus and method of controlling it

A method of controlling an X-ray CT apparatus, said X-ray CT apparatus being comprised of:

• 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 D0 corresponding to an amount of the X-rays detected by said detector, represented by a view angle and a channel of said detector;
• and
• an operating console having an axially projected data/pixel projection data calculating device for determining axially projected data D1 by projecting said projection data D0 obtained by said gantry onto a reference axis in a reconstruction region, and further determining pixel projection data D2 by projecting said axially projected data D1 onto coordinates of pixels constituting said reconstruction region, said operating console determining backprojection data D3 by adding said pixel projection data D2 determined by said axially projected data/pixel projection data calculating device for all views used in image reconstruction, said method comprising:
• an amount-of-offset measuring step of obtaining information indicative of an amount of offset of the position of said X-ray tube from a prespecified position;
• and
• a correcting step of correcting the axially projected data D1 or pixel projection data D2 determined at said axially projected data/pixel projection data calculating step using the information indicative of the amount of offset obtained at said amount-of-offset measuring step.

A program executing a method of controlling an X-ray CT apparatus, said X-ray CT apparatus being comprised of:

• 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 D0 corresponding to an amount of the X-rays detected by said detector, represented by a view angle and a channel of said detector;
• and
• an operating console having an axially projected data/pixel projection data calculating device for determining axially projected data D1 by projecting said projection data D0 obtained by said gantry onto a reference axis in a reconstruction region, and further determining pixel projection data D2 by projecting said axially projected data D1 onto coordinates of pixels constituting said reconstruction region, said operating console determining backprojection data D3 by adding said pixel projection data D2 determined by said axially projected data/pixel projection data calculating device for all views used in image reconstruction, said program comprising:
• a program for an amount-of-offset measuring step of obtaining information indicative of an amount of offset of the position of said X-ray tube from a prespecified position;
• and
• a program for a correcting step of correcting the axially projected data D1 or pixel projection data D2 determined at said axially projected data/pixel projection data calculating step using the information indicative of the amount of offset obtained at said amount-of-offset measuring step.