Radiation therapy system and method of operating radiation therapy apparatus

Abstract

The invention is to provide a radiation therapy system capable of widening a radiation irradiation range to a patient without increasing a burden on a structure. The radiation therapy system includes: a radiation source; a rotation mechanism that supports the radiation source and rotates the radiation source around an isocenter; a couch that places a therapy target site of a patient at the isocenter; a head swing mechanism that is disposed between the radiation source and the rotation mechanism and that swings an irradiation axis of a radiation emitted from the radiation source by swinging the radiation source; and a control unit that controls the radiation source, the rotation mechanism, and the head swing mechanism. The control unit holds the head swing mechanism in a state where the irradiation axis of the radiation of the radiation source is shifted from the isocenter in a predetermined direction by a predetermined amount, and rotates the radiation source by the rotation mechanism while emitting the radiation from the radiation source while maintaining the state of the head swing mechanism.