Patent Number: 
Section: claims

1. A radiation therapy apparatus comprising:a housing;a radiation source carried by said housing and including a radiation output having a first diameter;at least one aperture assembly carried by said housing and comprisinga radiation aperture body having an outside diameter less than the first diameter and an exposed upper surface with a shaped opening therein to control a radiation dosing profile,an aperture holder, an aperture-receiving passageway therein receiving said radiation aperture body, and having a recessed end, anda cover received within the recessed end of said aperture holder and retaining said radiation aperture body within said aperture holder, said cover having an opening aligned with the exposed upper surface of said radiation aperture body so as to define an interface therebetween that is exposed to the radiation output; anda radiation filter carried by said housing. 2. The radiation therapy apparatus according to claim 1 wherein said at least one aperture assembly comprises a plurality of stacked aperture assemblies. 3. The radiation therapy apparatus according to claim 1 wherein said radiation aperture body comprises a frusto-conical first portion; and wherein the aperture receiving passageway has a corresponding shape to the frusto-conical first portion. 4. The radiation therapy apparatus according to claim 1 wherein said radiation aperture body comprises a frusto-conical second portion; and wherein the opening of said cover has a corresponding shape to the frusto-conical second portion. 5. The radiation therapy apparatus according to claim 1 wherein the recessed end of said aperture holder and said cover define a threaded joint therebetween. 6. The radiation therapy apparatus according to claim 1 wherein said radiation aperture body comprises at least one alignment edge extending outwards therefrom; and wherein the aperture-receiving passageway further includes at least one recess receiving the at least one alignment edge. 7. The radiation therapy apparatus according to claim 1 wherein said radiation aperture body comprises brass. 8. The radiation therapy apparatus according to claim 1 wherein said aperture holder and said cover each comprises stainless steel. 9. The radiation therapy apparatus according to claim 1 wherein said radiation source generates protons. 10. An aperture assembly for radiation therapy comprising:a radiation aperture body having a shaped opening therein to control a radiation dosing profile, said radiation aperture body comprising a frusto-conical first portion;an aperture holder, an aperture-receiving passageway therein receiving said radiation aperture body, and having a recessed end; anda cover received within the recessed end of said aperture holder and retaining said radiation aperture body within said aperture holder, said cover having an opening aligned with the shaped opening in said radiation aperture body and having a shape corresponding to the frusto-conical first portion. 11. The aperture assembly according to claim 10 wherein said aperture holder has a disk shape. 12. The aperture assembly according to claim 10 wherein said aperture holder has a rectangular shape. 13. The aperture assembly according to claim 10 wherein said radiation aperture body comprises a frusto-conical second portion; and wherein the aperture receiving passageway has a corresponding shape to the frusto-conical second portion. 14. The aperture assembly according to claim 10 wherein the recessed end of said aperture holder and said cover define a threaded joint therebetween. 15. The aperture assembly according to claim 10 wherein said radiation aperture body comprises at least one alignment edge extending outwards therefrom; and wherein the aperture-receiving passageway further includes at least one recess receiving the at least one alignment edge. 16. The aperture assembly according to claim 10 wherein said radiation aperture body comprises brass. 17. The aperture assembly according to claim 10 wherein said aperture holder and said cover each comprises stainless steel. 18. A method for operating a radiation therapy apparatus comprising:providing a radiation source to generate a radiation output having a first diameter;positioning at least one aperture assembly within the radiation output of the radiation source, the at least one aperture assembly comprisinga radiation aperture body having an outside diameter less than the first diameter and an exposed upper surface with a shaped opening therein to control a radiation dosing profile,an aperture holder, an aperture-receiving passageway therein receiving the radiation aperture body, and having a recessed end, anda cover received within the recessed end of the aperture holder and retaining the radiation aperture body within the aperture holder, the cover having an opening aligned with the exposed upper surface of the radiation aperture body so as to define an interface therebetween that is exposed to the radiation output; andpositioning a radiation filter adjacent the at least one aperture assembly. 19. The method according to claim 18 wherein the radiation aperture body comprises a frusto-conical first portion; and wherein the aperture receiving passageway has a corresponding shape to the frusto-conical first portion. 20. The method according to claim 18 wherein the radiation aperture body comprises a frusto-conical second portion; and wherein the opening of the cover has a corresponding shape to the frusto-conical second portion. 21. The method according to claim 18 wherein the recessed end of the aperture holder and the cover define a threaded joint therebetween. 22. The method according to claim 18 wherein the radiation aperture body comprises at least one alignment edge extending outwards therefrom; and wherein the aperture-receiving passageway further includes at least one recess receiving the at least one alignment edge. 23. The method according to claim 18 wherein the radiation aperture body comprises brass. 24. The method according to claim 18 wherein the aperture holder and the cover each comprises stainless steel.