Particle therapy system (1) system has: circular accelerator (3),It is to accelerate charged particle； Beam delivery line,It is that the aforementioned charged particle being accelerated in circular accelerator (3) is directed at exposure cell (18)； Containment wall (23),It is that a what configures around the radioactive ray management region (16) of circular accelerator (3) and beam delivery line (4),Cover the radioactive ray as caused by circular accelerator (3) and beam delivery line (4)； Particular portion (34),It is to be located in containment wall (23) by the external position separated with radioactive ray management region (16),And adding for exposure cell (19) can be formed and use opening portion； And occlusive part (35),It is occlusion particular portion (34),And masking passes through the radioactive ray of the particular portion (34).粒子線治療系統(1)係具備：圓形加速器(3)，其係將荷電粒子加速；射束輸送線，其係將在圓形加速器(3)被加速的前述荷電粒子導至照射室(18)；遮蔽壁(23)，其係位於配置圓形加速器(3)及射束輸送線(4)的放射線管理區域(16)的周圍，遮蔽由圓形加速器(3)及射束輸送線(4)所產生的放射線；特定部(34)，其係設在遮蔽壁(23)中將外部與放射線管理區域(16)隔開的位置，且可形成照射室(19)的增設用開口部；及閉塞部(35)，其係閉塞特定部(34)，且遮蔽通過該特定部(34)的放射線。
