Patent ID: 7715520

Claim:
An X-ray computed tomography apparatus comprising: an X-ray source which generates X-rays; an X-ray detector which detects X-rays transmitted through a subject to be examined to generate projection data; a storage unit which stores the projection data in association with electrocardiographic data of the subject; a setting unit which sets a specific cardiac phase in accordance with an operator's instruction; a reconstruction unit which reconstructs an image on the basis of a plurality of projection data sets acquired in a plurality of specific periods throughout a plurality of cardiac cycles; a determining unit which determines a first period in which the subject is scanned by a high dose of X-rays in the cardiac cycles of the subject in order to include the specific cardiac phase even if a heart rate of the subject varies within a fluctuation range of the heart rate; and a control unit which controls a tube current of the X-ray source to generate a relatively high dose of X-rays in the first period and generate a relatively low dose of X-rays or stop a generation of X-rays in a second period other than the first period.