Patent Number: 
Section: claims

1. A medical particle irradiation apparatus comprising: a rotating gantry including an irradiation unit emitting particle beams;  a first frame located within and supported by said rotating gantry such that it can rotate relative to said rotating gantry;  a second frame fixedly located opposite said first frame;  an anti-corotation unit disposed on said rotating gantry, said anti-corotation unit being in contact with both said first and second frames to prevent said first frame from rotating together with said rotating gantry during rotation of said rotating gantry; and  a flexible moving floor located between said first and second frames, said flexible moving floor being engaged with said first and second frames in such a manner as to move freely such that its bottom is substantially level and that it moves as said rotating gantry rotates,  wherein said anti-corotation unit comprises a first rotational element having an uneven portion which meshes with a first uneven portion formed on said first frame, a second rotational element having an uneven portion which meshes with a second uneven portion formed on said second frame, and a shaft member which couples said first and second rotational elements together, wherein said shaft member is attached to said rotating gantry such that said shaft member is free to rotate on its axis. 2. The medical particle irradiation apparatus according to  claim 1 , wherein said first and second frames are each provided with a moving floor guide unit engaged separately with both ends of said moving floor, said moving floor guide unit having a level portion at the bottom. claim 1 3. The medical particle irradiation apparatus according to  claim 1 , wherein said first rotational element is in mesh with said first frame outwardly from the center of rotation of said rotating gantry, and said second rotational element is in mesh with said second frame outwardly from the center of rotation of said rotating gantry. claim 1 4. The medical particle irradiation apparatus according to  claim 1 , wherein said first rotational element is in mesh with said first frame toward the center of rotation of said rotating gantry from the outside thereof, and said second rotational element is in mesh with said second frame toward the center of rotation of said rotating gantry from the outside thereof. claim 1 5. A medical particle irradiation apparatus comprising: a rotating gantry including an irradiation unit emitting particle beams;  a first frame located within and supported by said rotating gantry such that it can rotate relative to said rotating gantry;  a second frame fixedly located opposite said first frame;  an anti-corotation unit disposed on said rotating gantry, said anti-corotation unit being in contact with both said first and second frames to keep the positions of said first and second frames, located opposite each other, substantially unchanged regardless of the rotation of said rotating gantry; and  a flexible moving floor located between said first and second frames, said flexible moving floor being engaged with said first and second frames in such a manner as to move freely such that its bottom is substantially level, that it forms therein a therapy room into which a therapy bed is slid and that it moves as said rotating gantry rotates,  wherein said anti-corotation unit comprises a first rotational element having an uneven portion which meshes with a first uneven portion formed on said first frame, a second rotational element having an uneven portion which meshes with a second uneven portion formed on said second frame, and a shaft member which couples said first and second rotational elements together, wherein said shaft member is attached to said rotating gantry such that said shaft member is free to rotate on its axis. 6. The medical particle irradiation apparatus according to  claim 5 , wherein said first and second frames are each provided with a moving floor guide unit engaged separately with both ends of said moving floor, said moving floor guide unit having a level portion at the bottom. claim 5 7. The medical particle irradiation apparatus according to  claim 5 , wherein said first rotational element is in mesh with said first frame outwardly from the center of rotation of said rotating gantry, and said second rotational element is in mesh with said second frame outwardly from the center of rotation of said rotating gantry. claim 5 8. The medical particle irradiation apparatus according to  claim 5 , wherein said first rotational element is in mesh with said first frame toward the center of rotation of said rotating gantry from the outside thereof, and said second rotational element is in mesh with said second frame toward the center of rotation of said rotating gantry from the outside thereof. claim 5 9. A medical particle irradiation apparatus comprising: a rotating gantry including an irradiation unit emitting particle beams;  a first frame located within and supported by said rotating gantry such that it can rotate relative to said rotating gantry;  a second frame fixedly located opposite said first frame;  a frame position retaining unit disposed on said rotating gantry and being in contact with both said first and second frames, said frame position retaining unit moving in the circumferential direction of said second frame as said rotating gantry rotates; and  a flexible moving floor located between said first and second frames, said flexible moving floor being engaged with said first and second frames in such a manner as to move freely such that its bottom is substantially level, that it forms therein a therapy room into which a therapy bed is slid and that it moves as said rotating gantry rotates, wherein  said frame position retaining unit comprises a first rotational element having an uneven portion which meshes with a first uneven portion formed on said first frame, a second rotational element having an uneven portion which meshes with a second uneven portion formed on said second frame, and a shaft member which couples said first and second rotational elements together, wherein said shaft member is attached to said rotating gantry such that said shaft member is free to rotate on its axis.