BEAM SHAPING ASSEMBLY FOR NEUTRON CAPTURE THERAPY

• US 20180250524A1
• Filed: 05/03/2018
• Published: 09/06/2018
• Est. Priority Date: 11/26/2015
• Status: Active Grant

• Current Assignee: Neuboron Medtech, Ltd.
• Original Assignee: Neuboron Medtech, Ltd.
• Inventors: LIU, Yuanhao, CHEN, Weilin, LEE, Peiyi
• Granted Patent: US 10,639,499 B2
• Time in Patent Office: Days
• CPC Class Codes: A61N 2005/109 Neutrons
• CPC Class Codes: A61N 2005/1094 Shielding, protecting against radiation
• CPC Class Codes: A61N 2005/1095 Elements inserted into the radiation path within the system, e.g. filters or wedges
• CPC Class Codes: A61N 5/10 X-ray therapy; Gamma-ray therapy; Particle-irradiation therapy A61N5/01 takes precedence
• CPC Class Codes: A61N 5/1078 Fixed beam systems
• CPC Class Codes: G21K 1/067 using surface reflection, e.g. grazing incidence mirrors, gratings multilayer mirrors G21K1/062; crystal optics G21K1/06
• CPC Class Codes: G21K 1/10 Scattering devices; Absorbing devices; Ionising radiation filters
• CPC Class Codes: G21K 1/12 Resonant absorbers or driving arrangements therefor, e.g. for Moessbauer-effect devices motors with reciprocating, oscillating or vibrating magnet, armature or coil system in general H02K33/00
• CPC Class Codes: G21K 2201/068 specially adapted for particle beams
• CPC Class Codes: H05H 2007/125 by mechanical means, e.g. stripping foils
• CPC Class Codes: H05H 2277/11 Radiotherapy
• CPC Class Codes: H05H 3/06 Generating neutron beams targets for producing nuclear reactions H05H6/00; neutron sources G21G4/02
• CPC Class Codes: H05H 6/00 Targets for producing nuclear reactions supports for targets or objects to be irradiated G21K5/08 ; preparation of tritium C01B4/00; targets, e.g. pellets for fusion reactions by laser or charged particles beam injection H05H1/22

Abstract

In order to improve flux and quality of neutron sources, the disclosure provides a beam shaping assembly for neutron capture therapy includes: a beam inlet; a target, wherein the target has nuclear reaction with an incident proton beam from the beam inlet to produce neutrons; a moderator adjoining to the target, wherein the neutrons are moderated by the moderator to epithermal neutron energies, the moderator includes a main body and a supplement section surrounding the main body, the main body and the supplement section form at least a tapered structure; a reflector surrounding the moderator; a thermal neutron absorber adjoining to the moderator; a radiation shield arranged inside the beam shaping assembly, wherein the radiation shield is used for shielding leaking neutrons and photons so as to reduce dose of the normal tissue not exposed to irradiation; and a beam outlet.

Claims

1. A beam shaping assembly for neutron capture therapy comprising:

a beam inlet;

a target, wherein the target has nuclear reaction with an incident proton beam from the beam inlet to produce neutrons, the neutrons form a neutron beam, and the neutron beam defines an axis;

a moderator adjoining to the target, wherein the neutrons are moderated by the moderator to epithermal neutron energies, the moderator comprises a main body and a supplement section surrounding the main body, the main body and the supplement section form at least a tapered structure;

a reflector surrounding the moderator, wherein the reflector leads the neutrons deviated from the axis back to enhance epithermal neutron beam intensity;

a thermal neutron absorber adjoining to the moderator, wherein the thermal neutron absorber is used for absorbing thermal neutrons so as to avoid overdosing in superficial normal tissue during therapy;

a radiation shield arranged inside the beam shaping assembly, wherein the radiation shield is used for shielding leaking neutrons and photons so as to reduce dose of the normal tissue not exposed to irradiation; and

a beam outlet.

2. The beam shaping assembly for neutron capture therapy according to claim 1, wherein the main body comprises at least a tapered section adjoining to the target and a cylindrical section adjoining to the tapered section, the supplement section surrounds the cylindrical section and connects with the tapered section so as to form the tapered structure.

3. The beam shaping assembly for neutron capture therapy according to claim 1, wherein the moderator comprises two tapered structures adjoining to each other in opposite directions.

4. The beam shaping assembly for neutron capture therapy according to claim 3, wherein the main body comprises two tapered sections and a cylindrical section, the two tapered sections are arranged at the two ends of the cylindrical section respectively, the supplement section surrounds the cylindrical section and connects to the two ends of the cylindrical section, the main body and the supplement section form two tapered structures adjoining to each other in opposite directions.

5. The beam shaping assembly for neutron capture therapy according to claim 1, wherein the beam shaping assembly is further used for accelerator-based boron neutron capture therapy.

6. The beam shaping assembly for neutron capture therapy according to claim 1, wherein the incident proton beam is accelerated by means of an accelerator and generates nuclear reaction with the target made of a metal material to produce neutrons.

7. The beam shaping assembly for neutron capture therapy according to claim 1, wherein neutrons are moderated to the epithermal neutron energies and thermal neutrons and fast neutrons are reduced, the epithermal neutron energy region is between 0.5 eV and 40 keV, the thermal neutron energy region is lower than 0.5 eV, and the fast neutron energy region is higher than 40 keV;

and the moderator is made of a material having a large action section with fast neutrons and a small action section with epithermal neutrons, the reflector is made of a material having high neutron reflection capability, and the thermal neutron absorber is made of a material having a large action section with thermal neutrons.

8. The beam shaping assembly for neutron capture therapy according to claim 1, wherein the main body and the supplement section are made from different materials.

9. The beam shaping assembly for neutron capture therapy according to claim 1, wherein the main body is prepared from at least one of D₂O, AlF₃, CaF₂, Li₂CO₃, MgF₂ and Al₂O₃, the reflector is prepared from any one of Pb and Ni, the thermal neutron absorber is prepared from ⁶Li, an air passage is arranged between the thermal neutron absorber and the beam outlet, and the radiation shield comprises photon shield and neutron shield.

10. The beam shaping assembly for neutron capture therapy according to claim 1, wherein the supplement section is prepared from any one of Zn, Mg, Al, Ti, La, Pb, Zr and Bi.

11. A beam shaping assembly for neutron capture therapy comprising:

a beam inlet;

a target, wherein the target has nuclear reaction with an incident proton beam from the beam inlet to produce neutrons, the neutrons form a neutron beam, and the neutron beam defines an axis;

a moderator adjoining to the target, wherein the neutrons are moderated by the moderator to epithermal neutron energies, the moderator comprises a main body and a supplement section surrounding the main body, the materials of the main body and the supplement section are different;

a reflector surrounding the moderator, wherein the reflector leads deflected neutrons back to enhance epithermal neutron beam intensity;

a thermal neutron absorber adjoining to the moderator, wherein the thermal neutron absorber is used for absorbing thermal neutrons so as to avoid overdosing in superficial normal tissue during therapy;

a radiation shield arranged inside the beam shaping assembly, wherein the radiation shield is used for shielding leaking neutrons and photons so as to reduce dose of the normal tissue not exposed to irradiation; and

a beam outlet.

12. The beam shaping assembly for neutron capture therapy according to claim 11, wherein the main body is prepared from at least one of D₂O, AlF₃, CaF₂, Li₂CO₃, MgF₂ and Al₂O₃, the reflector is prepared from any one of Pb and Ni, the thermal neutron absorber is prepared from ⁶Li, an air passage is arranged between the thermal neutron absorber and the beam outlet, and the radiation shield comprises photon shield and neutron shield.

13. The beam shaping assembly for neutron capture therapy according to claim 11, wherein the supplement section is prepared from any one of Zn, Mg, Al, Ti, La, Pb, Zr and Bi.

14. The beam shaping assembly for neutron capture therapy according to claim 11, wherein the supplement section surrounds the main body and forms at least a tapered structure.

15. The beam shaping assembly for neutron capture therapy according to claim 14, wherein the main body comprises at least a tapered section adjoining to the target and a cylindrical section adjoining to the tapered section, the supplement section surrounds the cylindrical section and connects to the tapered section so as to form the tapered structure.

16. The beam shaping assembly for neutron capture therapy according to claim 14, wherein the moderator comprises two tapered structures adjoining to each other in opposite directions.

17. The beam shaping assembly for neutron capture therapy according to claim 16, wherein the main body comprises two tapered sections and a cylindrical section, the two tapered sections are arranged at the two ends of the cylindrical section respectively, the supplement section surrounds the cylindrical section and connects with the two ends of the cylindrical section, the main body and the supplement section shape two tapered structures adjoining to each other in opposite directions.

18. Abeam shaping assembly for neutron capture therapy comprising:

a beam inlet;

a target, wherein the target has nuclear reaction with an incident proton beam from the beam inlet to produce neutrons, the neutrons form a neutron beam, and the neutron beam defines an axis;

a moderator adjoining to the target, wherein the neutrons are moderated by the moderator to epithermal neutron energies, the moderator comprises a main body and a supplement section, the main body comprises at least a tapered section adjoining to the target and defines an outer wall, the supplement section surrounds the main body and defines an inner wall connected with the outer wall, and the supplement section is arranged far from the target than the main body;

a reflector surrounding the moderator, wherein the reflector leads deflected neutrons back to enhance epithermal neutron beam intensity;

a thermal neutron absorber adjoining to the moderator, wherein the thermal neutron absorber is used for absorbing thermal neutrons so as to avoid overdosing in superficial normal tissue during therapy;

a radiation shield arranged inside the beam shaping assembly, wherein the radiation shield is used for shielding leaking neutrons and photons so as to reduce dose of the normal tissue not exposed to irradiation; and

a beam outlet.

19. The beam shaping assembly for neutron capture therapy according to claim 18, wherein the main body also comprises a tapered section adjoining to the thermal neutron absorber and a cylindrical section, the two tapered sections are arranged at the two ends of the cylindrical section respectively, the supplement section surrounds the periphery of the cylindrical section and connects with the two ends of the cylindrical section, the main body and the supplement section shape two tapered structures adjoining to each other in opposite directions.

20. The beam shaping assembly for neutron capture therapy according to claim 18, wherein the main body and the supplement section are made from different materials.