PARTICLE IRRADIATION APPARATUS, PARTICLE BEAM IRRADIATION METHOD AND PARTICLE TREATMENT SYSTEM

摘要

A particle irradiation apparatus and a particle beam irradiation method that controls the energy and irradiation dose of a particle beam to form a high dose region having a high uniformity of depth-directional spread (Spread Out Bracici Peak, referred to as SOBP). A SOBP having a steep falling edge of the dose distribution on the deep side from the body surface is formed based on a method of superimposing SOBPs each having a small dose distribution width to form a desired SOBP. An energy-spread-device forms a first SOBP having a small dose distribution width; and an energy spread device 2 forms a second SOBP having a small dose distribution width and a steep falling edge of the dose distribution at the deepest portion from the body surface. The thus formed SOBPs are superimposed to form a SOBP having a length suitable for the target region.