To provide a structure which downsizes a gantry body, ensures a space for a rotary irradiation chamber in the gantry body and a space around a II tube device which is at the back of the irradiation chamber and stably forms a flat floor constituting the rotary irradiation chamber in a broad angle of rotation.
A medical particle beam irradiator is provided with a rotary gantry the tube of which keeps a particle beam irradiating part for emitting particle beams arranged in a part, a rear panel 16 which is arranged at the back of a region of passage of the particle beam irradiating part 9 in the rotary gantry, a fixed floor 17 which is inserted from outside the rotary gantry toward the inside of the tube and does not reach the region of passage of the particle beam irradiating part 9 and a moving floor mechanism 20 which is arranged between the rear panel 16 and the fixed floor 17. A floor whose lower side is maintained substantially horizontal by the moving floor mechanism 20 and the fixed floor 17 is formed. A particle radiation therapy chamber 18 for particle radiation therapy whose depth is specified by the rear panel 16 is formed in the rotary gantry.
TAKEDA NORIO
YANAGISAWA MASAKI
YAMASHITA TSUTOMU
Yuji Toda