Patent ID: 8575564

Claim:
A particle beam irradiation apparatus having a scanning irradiation system that performs scanning with a charged particle beam accelerated by an accelerator and being mounted in a rotating gantry for rotating the irradiation direction of the charged particle beam, the particle beam irradiation apparatus comprising: a columnar-irradiation-field generation apparatus for generating a columnar irradiation field by enlarging the Bragg peak of the charged particle beam, said columnar irradiation-field generation apparatus including: at least one pair of upstream deflection electromagnets and at least one pair of downstream deflection electromagnets, wherein (i) a first deflection electromagnet of the pair of upstream deflection electromagnets deflects the charged particle beam at a predetermined angle with respect to an original beam path and (ii) a second electromagnet of the pair of upstream deflection electromagnets deflects the deflected charged particle beam such that it is parallel with respect to the original beam path, an energy changing apparatus for changing the energy of the charged particle beam, a depth-direction irradiation field enlargement apparatus for enlarging the Bragg peak of the charged particle beam, and a controller that controls the energy changing apparatus in conjunction with the depth-direction irradiation field enlargement apparatus so that the columnar irradiation field of the charged particle beam, entering an irradiation subject from any one of a plurality of different directions, is generated at a depth of the irradiation subject that conforms to a shape of a distal end portion of the irradiation subject.