Patent ID: 7297967

Claim:
A particle beam irradiation system comprising: a charged particle beam generation apparatus; and an irradiation apparatus for exposing an irradiation target to a charged particle beam emitted from the charged particle beam generation apparatus; wherein said irradiation apparatus includes: a beam scanner for scanning said charged particle beam in such a manner as to draw a circle in a plane perpendicular to a propagation direction of said charged particle beam; a scattering device for increasing the size of said charged particle beam; a Bragg peak spreading device through which said charged particle beam passes; a collimator disposed downstream of said beam scanner, said scattering device and said Bragg peak spreading device in the propagation direction of said charged particle beam for eliminating the charged particle beams other than those which pass therethrough; and a plurality of drive devices including a first drive device for moving said scattering device in said propagation direction of said charged particle beam, and a second drive device for moving said Bragg peak spreading device in said propagation direction of said charged particle beam.