Patent ID: 7085347

Claim:
A radiotherapy apparatus comprising: a bed which carries a subject; a radiation irradiating head which irradiates a treatment radiation to a treatment field of said subject; a support frame supporting said radiation irradiating head and having a gimbal structure, said support frame being installed at a position which includes an inertia center of said radiation irradiating head and through which a first axis and a second axis pass, said support frame having at least a first side, second side, third side, and fourth side; a first head swing mechanism which is linked to said radiation irradiating head, and swings generally around the first axis at the inertia center of said radiation irradiating head, wherein said first head swine mechanism includes at least a driving shaft and swing driving servomotor installed at the first side of said support frame; a second head swing mechanism which is linked to said radiation irradiating head, and swings generally around the second axis at the inertia center of said radiation irradiating head, wherein said second head swing mechanism includes at least a driving shaft and swing driving servomotor installed at the second side of said support frame; an inspection unit which detects a diagnosis image containing said treatment field; and a control unit which controls a position of said head swing mechanisms such that an irradiation field of said radiation irradiating head pursues said treatment field, based on said diagnosis image, said position of said radiation irradiating head and a swung state of said radiation irradiating head; wherein said control unit controls said radiation irradiating head such that said treatment radiation is irradiated from said radiation irradiating head, after the positional control of said head swing mechanisms.