Particle beam irradiation system and method of adjusting irradiation field forming apparatus

摘要

A particle therapy system, as one example of a particle beam irradiation system, comprises a charged particle beam generator (2) and an irradiation field forming apparatus (15). An ion beam from the charged particle beam generator (2) is irradiated to a diseased part in the body of a patient through the irradiation field forming apparatus (15). A scattering compensator (34) and a range modulation wheel (24) are disposed on the upstream side in a direction of beam advance and are movable along a beam axis. The movement of the scattering compensator (34) and the range modulation wheel (24) adjusts the size of the ion beam entering a scatterer device (18), whereby a change in scattering intensity of the ion beam in the scatterer device (18) is adjusted. As a result, a penumbra in dose distribution is reduced and a more uniform dose distribution in a direction perpendicular to the direction of beam advance is obtained in the diseased part.