Patent Number: 
Section: claims

1. A neutron capture therapy system, comprising a beam shaping assembly, wherein the beam shaping assembly comprises,a beam inlet;a neutron generator arranged in the beam shaping assembly, wherein the neutron generator has nuclear reaction with an incident proton beam from the beam inlet to produce neutrons;a moderator adjoining to the neutron generator, wherein the neutrons are moderated by the moderator to epithermal neutron energies;a reflector surrounding the neutron generator and the moderator, wherein the reflector leads the deflected neutrons back to enhance the epithermal neutron beam intensity;a beam outlet; andat least a movable member moving away from or close to the neutron generator, wherein the movable member moves between a first position where the neutron generator is replaceable and a second position where the neutron generator is irreplaceable. 2. The neutron capture therapy system according to claim 1, wherein the movable member is part of the reflector or a combination of part of the reflector and part of the moderator. 3. The neutron capture therapy system according to claim 1, wherein the reflector defines a first linear height, the movable member defines a second linear height, the neutron generator defines a third linear height, and the second linear height is smaller than or equal to the first linear height and is greater than the third linear height. 4. The neutron capture therapy system according to claim 3, wherein the movable member defines a symmetry plane, the movable member is symmetrical with respect to the symmetry plane, and the symmetry plane passes through an axis of the neutron generator. 5. The neutron capture therapy system according to claim 2, wherein the reflector includes a first connecting part which comprises a first connecting surface and a first junction surface; the movable member includes a second connecting part which comprises a second connecting surface and a second junction surface; the first connecting surface connects with the second connecting surface and is overlapped with the second connecting surface, the first junction surface connects with the second junction surface and is overlapped with the second junction surface, and the second junction surface is overlapped with the plane where the axis of the neutron generator is in. 6. The neutron capture therapy system according to claim 3, wherein when the second liner height is smaller than the first linear height and greater than the third height, the first connecting surface and the first junction surface are overlapped, the second connecting surface and the second junction surface are overlapped; when the second linear height is equal to the first linear height, the first connecting surface and the first junction surface are connected but are located in different planes, the second connecting surface and the second junction surface are connected but are located in different planes, the first connecting surface connects with the second connecting surface and is overlapped with the second connecting surface, and the first junction surface connects with the second junction surface and is overlapped with the second junction surface. 7. The neutron capture therapy system according to claim 1, wherein the neutron capture therapy system further comprises a driving assembly; the driving assembly comprises at least a gate to support the movable member, and a guide rail for allowing the gate to move away from or close to the neutron generator; when the gate moves away from the beam shaping assembly, the movable member moves to the first position; and when the gate moves close to the beam shaping assembly, the movable member moves to the second position. 8. The neutron capture therapy system according to claim 7, wherein the guide rail is arranged outside the beam shaping assembly, the gate moves away from or close to the beam shaping assembly along the guide rail. 9. The neutron capture therapy system according to claim 6, wherein the guide rail is arranged outside the beam shaping body, the driving assembly further comprises supporting a frame, one end of the supporting frame is used for supporting the gate, the other end of the supporting frame moves in the guide rail, and the gate moves away from or close to the beam shaping assembly as the supporting frame moves along the guide rail. 10. The neutron capture therapy system according to claim 2, wherein when the second linear height is smaller than the first linear height and is greater than the third linear height, a guide rail is arranged in the reflector, and the movable member is arranged in the beam shaping assembly and moves away from or close to the neutron generator through the guide rail. 11. A neutron capture therapy system, comprising a beam shaping assembly, wherein the beam shaping assembly comprises,a beam inlet,a neutron generator arranged in the beam shaping assembly, wherein the neutron generator has nuclear reaction with an incident proton beam from the beam inlet to produce neutrons;a moderator adjoining to the neutron generator, wherein the neutrons are moderated by the moderator to epithermal neutron energies;a reflector surrounding the moderator, wherein the reflector leads the deflected neutrons back to enhance the epithermal neutron beam intensity;a beam outlet; andat least a movable member moving away from or close to the neutron generator, wherein the movable member moves between a first position where the neutron generator is replaceable and a second position where the neutron generator is irreplaceable, and wherein the movable member defines a curved surface, when the moveable member moves away from the beam shaping assembly, a notch is shaped on the beam shaping assembly where the neutron generator is replaced; and when the moveable member moves close to the beam shaping assembly, the curved surface surrounds at least half of the neutron generator. 12. The neutron capture therapy system according to claim 11, wherein the movable member is a part of the reflector or a combination of part of the reflector and part of the moderator. 13. The neutron capture therapy system according to claim 11, wherein the reflector defines a first linear height, the movable member defines a second linear height, the neutron generator defines a third linear height, and the second linear height is smaller than or equal to the first linear height and is greater than the third linear height. 14. The neutron capture therapy system according to claim 11, wherein the movable member defines a symmetry plane, the movable member is symmetrical with respect to the symmetry plane; the symmetry plane passes through an axis of the neutron generator. 15. The neutron capture therapy system according to claim 11, wherein the neutron capture therapy system further comprises a driving assembly; the driving assembly comprises at least a gate for supporting the movable member, and a guide rail for allowing the gate to move away from or close to the neutron generator; the guide rail is arranged outside the beam shaping assembly, and the gate moves away from or close to the beam shaping assembly through the guide rail, the movable member moves away from or close to the neutron generator along the guide rail. 16. The neutron capture therapy system according to claim 15, wherein the driving assembly further comprises a supporting frame, one end of the supporting frame supports the gate, the other end of the supporting frame moves in the guide rail, and the gate moves away from or close to the beam shaping assembly as the supporting frame moves along the guide rail. 17. The neutron capture therapy system according to claim 11, wherein when the second linear height is smaller than the first linear height and is greater than the third linear height, a guide rail is arranged in the reflector, and the movable member is arranged in the beam shaping assembly and moves away from or close to the neutron generator through the guide rail. 18. A neutron capture therapy system, comprising a beam shaping assembly, wherein the beam shaping assembly comprises,a beam inlet;a neutron generator arranged in the beam shaping assembly, wherein the neutron generator has nuclear reaction with an incident proton beam from the beam inlet to produce neutrons;a moderator adjoining to the neutron generator, wherein the neutrons are moderated by the moderator to epithermal neutron energies;a reflector surrounding the moderator, wherein the reflector leads the deflected neutrons back to enhance the epithermal neutron beam intensity, and wherein the reflector includes a first connecting surface and a first junction surfaces connects to the first connecting surface;a beam outlet; andat least a movable member moving away from or close to the neutron generator, wherein the movable member moves between a first position where the neutron generator is replaceable and a second position where the neutron generator is irreplaceable, and wherein the movable member defines a second connecting surface and a second junction surface connected with the second connecting surface, the second connecting surface is overlapped with the first connecting surface, the second junction surface is overlapped with the first junction surface, when the moveable member moves away from the neutron generator, the first connecting surface is separated from the second connecting surface, the first junction surface is separated from the second junction surface, and the neutron generator is replaceable. 19. The neutron capture therapy system according to claim 18, wherein the first connecting surface is inclined to the first junction surface, the second connecting surface is inclined to the second junction surface. 20. The neutron capture therapy system according to claim 18, wherein the second junction surface includes a recess, the first junction surface includes a protrusion for engaging to the recess in a form-fitting manner.