X-ray computed tomography apparatus

The invention addresses the problem of starting projection data acquisition from a selected patient table position or rotation angle. A position-determining unit determines the position of the patient table at the scheduled starting time for projection data acquisition by the data acquisition system according to the user's instructions. A first angle-determining unit determines a first X-ray tube rotation angle at the scheduled acquisition starting time according to the user's instructions. A second angle-determining unit determines a second X-ray tube rotation angle at the scheduled movement starting time on the basis of the determined first rotation angle and the time interval from the scheduled patient table movement start time until the scheduled acquisition start time. A control unit controls the rotation actuator to rotate the X-ray tube around the subject, controls the patient table-moving unit so that the patient table begins to move when the X-ray tube reaches the second rotation angle, and controls the data acquisition system so as to begin projection data acquisition when the patient table reaches the determined patient table position.