Patent ID: 7123680

Claim:
An X-ray computer tomography apparatus, comprising: an X-ray tube that generates an X-ray; an X-ray detector for detecting an X-ray transmitted through a subject; a collection unit that collects X-ray signals from the X-ray detector repeatedly; a shutter mechanism unit that is arranged between the X-ray tube and the subject in order to convert the generated X-ray into a pulse X-ray and is constituted such that a ratio of a shutter open period and a shutter close period is variable; a restructuring unit that restructures image data on the basis of the collected X-ray signals: and a control unit that controls the shutter mechanism unit in order to change the ratio of a shutter open period and a shutter close period; wherein the control unit changes the ratio of a shutter open period and a shutter close period dynamically during a helical scan; and wherein the control unit calculates the ratio of a shutter open period and a shutter close period individually with respect to plural slice positions on the basis of scanogram data of the subject.