Patent ID: 7449701

Claim:
Particle beam irradiation equipment comprising charged particle beam generation equipment and a charged particle beam irradiation nozzle for irradiating a charged particle beam extracted from said charged particle beam generation equipment to an irradiation target, wherein said charged particle beam irradiation nozzle comprises: a first scatterer device including a first scatterer through which said charged particle beam passes; a second scatterer device including a plurality of second scatterers through which an unoccluded Gaussian distributed charged particle beam passes after having passed said first scatterer, said second scatterer device causing one of said plurality of second scatterers to position in a passage region of said charged particle beam at one of plural different positions in the direction of travel of said charged particle beam; and a collimator for shaping said charged particle beam, said plurality of second scatterers of the second scatterer device each being configured to have higher scatter strength in the central side than in the radially outer peripheral side to provide a beam irradiation of a double scattering method in combination with said first scatterer of the first scatterer device, said plurality of second scatterers including a second scatterer for smaller irradiation field size caused to position in said passage region at a first position in the direction of travel of said charged particle beam and used when said collimator is adapted for a relatively small first irradiation field and another second scatterer for larger irradiation field size caused to position in said passage region at a second position upstream of said first position in the direction of travel of said charged particle beam and used when said collimator is adapted for a larger second irradiation field than said first irradiation field, said second scatterer for smaller irradiation field size caused to position in the passage region at said first position having a thickness different from that of said another second scatterer for larger irradiation field caused to position in the passage region at said second position so as to provide smaller scattering strength of said charged particle beam in a direction perpendicular to the direction of travel of said charged particle beam than said another second scatterer for larger irradiation field size.