Patent ID: 8170176

Claim:
An X-ray CT system comprising: a mount; an X-ray tube configured to irradiate a beam with a fan angle; a top board on which a subject is placed; an X-ray detector that is arranged opposite to said X-ray tube by sandwiching said subject that has been placed on said top board, the X-ray detector having a plurality of detection elements arranged in the spreading direction of said fan angle; a drive part configured to move said top board relative to said mount along the body-axis direction of said subject; a rotating part configured to support said X-ray tube and said X-ray detector to said mount to be integrally rotatable about the body axis of said subject; a rotation controlling part configured to control said rotating part so as to cause said X-ray tube to stop at a first position located above said subject or a second position located to the side of said subject; an imaging-condition setting part configured to set a plurality of CT-image imaging conditions, including an electric amount for driving and controlling the X-ray tube during CT imaging, based on a scout image that has been imaged by irradiating X-rays from said X-ray tube, to said subject on said top board that has been moved relative to a specified position by said drive part, that has been stopped at at least one of said first position and said second position; a judging part configured to judge whether any of said detection elements is expected to detect an X-ray dosage exceeding a predetermined value and to output the judgment result when capturing CT images based on the set CT-image imaging conditions; a determining part, based on information of the arranged positions of said detection elements that are expected to detect an X-ray dosage exceeding said first predetermined value, configured to determine whether at least one of the shift amounts of said horizontal position and said vertical positions of said top board exceeds a predetermined value and outputs said determination result; and a position adjusting part configured to adjust the position of said top board in the horizontal and vertical directions that are orthogonal to the body-axis direction of said subject, wherein said position adjusting part, upon receiving a determination result provided by said determining part that said horizontal position shift of said top board exceeds a predetermined value, configured to adjust said horizontal position of said top board so as to eliminate the shift amount of said horizontal position of said top board, and, upon receiving a determination result provided by said determining part that said vertical position shift of said top board exceeds a predetermined value, is configured to adjust said vertical position of said top board so as to eliminate the shift amount of said vertical position of said top board.