Particle beam therapy apparatus

1. A particle beam therapy apparatus comprising:

a particle beam irradiator configured to output a particle beam;

a supporting structure configured to be movable and support the particle beam irradiator;

a plurality of movable plates disposed on a displacement trajectory of the particle beam irradiator, forming a substantially horizontal enveloping surface below a table for placing an irradiation object, comprising in at least one of the plurality of movable plates:

a first floor member; and

a second floor member smaller in X-ray transmittance than the first floor member;

an X-ray generator provided in a non-collision area where the X-ray generator does not collide with any of the particle beam irradiator, the supporting structure, and the plurality of movable plates; and

an X-ray detector installed at a position where the X-ray detector faces the X-ray generator and detects X-rays transmitted through the first floor member.

2. The particle beam therapy apparatus according to claim 1 ,

wherein the X-ray generator is supported by the supporting structure.

3. The particle beam therapy apparatus according to claim 1 ,

wherein the X-ray detector is supported by the supporting structure.

4. The particle beam therapy apparatus according to claim 1 ,

wherein respective first floor members are provided in adjacent two or more of the movable plates.

5. The particle beam therapy apparatus according to claim 4 ,

wherein the respective first floor members provided in the adjacent two or more of the movable plates are continuously disposed without interposing the second floor member.

6. The particle beam therapy apparatus according to claim 1 , further comprising:

a sensor configured to detect a position of the first floor member; and

a position adjuster configured to dispose the first floor member on an irradiation area of the X-ray by moving the plurality of movable plates based on the position of the first floor member.

7. The particle beam therapy apparatus according to claim 1 ,

wherein the plurality of movable plates are divided into plural groups;

adjacent movable plates in each of the plural groups form one moving sheet by being connected with each other; and

distance between a centroid of one moving sheet and a centroid of another adjacent moving sheet changes.

8. The particle beam therapy apparatus according to claim 1 ,

wherein transmission path length of incident X-rays into the first floor member does not suddenly change when positional relationship between the first floor member and the X-ray generator changes.

9. The particle beam therapy apparatus according to claim 1 ,

wherein a material constituting the first floor member is CFRP.

10. The particle beam therapy apparatus according to claim 1 ,

wherein the supporting structure is a cylindrical rotating structure that rotates around the irradiation object.

11. The particle beam therapy apparatus according to claim 1 ,

wherein the supporting structure rotates at an angle of 270 degrees or less around the irradiation object.

12. The particle beam therapy apparatus according to claim 1 ,

wherein the plurality of movable plates move along a circumferential direction of the particle beam irradiator.

13. The particle beam therapy apparatus according to claim 1 ,

wherein the plurality of movable plates move in a direction perpendicular to a circumferential direction of the particle beam irradiator.