PROBLEM TO BE SOLVED: To make it possible to shorten an irradiation time, reduce temporal loads on a subject to be irradiated, and also improve the precision of irradiation.SOLUTION: In the particle beam irradiation system 10 having an accelerator 12 for emitting a charged particle beam 2 and a radiator 20 for performing scanning irradiation of the charged particle beam emitted by the accelerator to the subject 6 to be irradiated where a cycle fluctuates many times, the system is provided with: a means for modulating beam intensity which modulates the beam intensity from the accelerator (S2) to supply an amount of beam irradiation corresponding to a size of each scanning region formed in a layer by dividing the object to be radiated in a beam axial direction and a means for performing scanning irradiation of each amount of beam irradiation which is supplied by the charged particle beam modulated by the means for modulating the beam intensity during a gate period when a displacement amount of cycle fluctuation of the object to be radiated is within a prescribed phase (S3, S4, and S5).COPYRIGHT: (C)2008,JPO&INPIT【課題】照射時間を短縮し、照射対象に対する時間の負荷を軽減させるだけでなく、照射精度を向上させることができるようにする。【解決手段】荷電粒子ビーム2を出射する加速器12と、該加速器から出射された荷電粒子ビームを周期変動する照射対象6に複数回スキャニング照射する照射装置20と、を有する粒子線照射システム10において、前記照射対象をビーム軸方向に分割して層状に形成される各スキャン領域の大きさに対応する照射線量を、前記加速器からのビーム強度を変調(S2)させて供給させるビーム強度変調手段と、該ビーム強度変調手段によって変調された荷電粒子ビームにより供給される前記各照射線量を、前記照射対象の周期変動の変位量が所定位相内にあるゲート期間に、前記各スキャン領域に対してスキャニング照射(S3、S4、S5)させる手段と、を備える。【選択図】図1
