Patent ID: 6936832

Claim:
A particle therapy system comprising an accelerator for accelerating a charged-particle beam to a set level of energy, and a rotating irradiation facility for irradiating the charged-particle beam extracted from said accelerator, said irradiation facility comprising beam transport apparatus for transporting the charged-particle beam extracted from said accelerator, and irradiation field forming apparatus for forming an irradiation field of the charged-particle beam transported by said beam transport apparatus, wherein said particle therapy system further comprises: first beam position detecting apparatus arranged along an orbit of the charged-particle beam downstream of a bending magnet arranged most downstream in said beam transport apparatus, and detecting a position at which the charged-particle beam passes; second beam position detecting apparatus arranged along the orbit of the charged-particle beam downstream of said first beam position detecting apparatus, and detecting a position at which the charged-particle beam passes; a first steering magnet and a second steering magnet both provided in said first beam transport apparatus upstream of said first beam position detecting apparatus; displacement amount computing apparatus for determining respective displacement amounts by which the position of the charged-particle beam is to be displaced by said first and second steering magnets, in accordance with detected signals outputted from said first and second beam position detecting apparatus; and control system for controlling respective excitation currents of said first and second steering magnets in accordance with said respective displacement amounts.