BEAM SHAPING ASSEMBLY FOR NEUTRON CAPTURE THERAPY

• US 20180085604A1
• Filed: 11/29/2017
• Published: 03/29/2018
• Est. Priority Date: 12/08/2014
• Status: Active Grant

• Current Assignee: Neuboron Medtech, Ltd.
• Original Assignee: Neuboron Medtech, Ltd.
• Inventors: Liu, Yuan-Hao, Lee, Pei-Yi
• Granted Patent: US 10,124,192 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 5/1077 Beam delivery systems
• CPC Class Codes: G21G 4/02 Neutron sources
• CPC Class Codes: G21K 1/10 Scattering devices; Absorbing devices; Ionising radiation filters
• 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

A beam shaping assembly for neutron capture therapy includes a beam inlet, a target having nuclear reaction with an incident proton beam from the beam inlet to produce neutrons forming a neutron beam defining a main axis, a moderator adjoining to the target, a reflector surrounding the moderator, a thermal neutron absorber adjoining to the moderator, a radiation shield arranged inside the beam shaping assembly and a beam outlet. The neutrons are moderated to epithermal neutron energies. The reflector leads the neutrons deviated from the main axis back, and a gap channel is arranged between the moderator and the reflector. The thermal neutron absorber is used for absorbing thermal neutrons so as to avoid overdosing in superficial normal tissue during therapy. The radiation shield is used for shielding leaking neutrons and photons so as to reduce dose of the normal tissue not exposed to irradiation.

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, and wherein the neutrons form a neutron beam defining a main axis;

a moderator adjoining to the target, wherein the neutrons are moderated by the moderator to epithermal neutron energies;

a reflector surrounding the moderator, wherein the reflector leads the neutrons deviated from the main 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,

wherein an outer surface of the moderator includes a first single flat tapered section tapered in a first direction away from the beam outlet.

2. 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.

3. The beam shaping assembly for neutron capture therapy according to claim 2, wherein a proton beam is accelerated by means of an accelerator to overcome coulomb repulsion energy of a target atomic nucleus and generate nuclear reaction with the target to produce neutrons, and the target is made of a metal material.

4. The beam shaping assembly for neutron capture therapy according to claim 1, wherein an epithermal neutron energy range ranges from 0.5 eV to 40 keV, a thermal neutron energy range is below 0.5 eV, and a fast neutron energy range is above 40 keV, and the beam shaping assembly reduces the quantity of thermal neutrons and fast neutrons;

and wherein the moderator is made of a material having a cross section for principally acting with fast neutrons but hardly acting with epithermal neutrons, the reflector is made of a material having a high neutron reflection ability, and the thermal neutron absorber is made of a material having a cross section for acting with thermal neutrons.

5. The beam shaping assembly for neutron capture therapy according to claim 4, wherein the moderator is made of at least one of D₂O, AlF₃, CaF₂, Li₂CO₃, MgF₂ and Al₂O₃.

6. The beam shaping assembly for neutron capture therapy according to claim 4, wherein the reflector is made of at least one of Pb or Ni, and the thermal neutron absorber is made of ⁶Li, and wherein an air passage is arranged between the thermal neutron absorber and the beam outlet.

7. The beam shaping assembly for neutron capture therapy according to claim 1, wherein the radiation shield includes a photon shield and a neutron shield.

8. The beam shaping assembly for neutron capture therapy according to claim 1, wherein all of the beam inlet, the moderator and the beam outlet are extended along the main axis.

9. The beam shaping assembly for neutron capture therapy according to claim 1, wherein an outer surface of the moderator includes a second single flat tapered section adjioning to the first single flat tapered section and tapered in a second direction toward the beam outlet.

10. The beam shaping assembly for neutron capture therapy according to claim 1, wherein the beam shaping assembly includes a gap channel arranged between the moderator and the reflector and enclosed by the reflector, the moderator and the thermal neutron absorber, and wherein the gap channel allows neutron beams to pass for enhancing epithermal neutron beam intensity.

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, and wherein the neutrons form a neutron beam defining a main axis;

a moderator adjoining to the target, wherein the neutrons are moderated by the moderator to epithermal neutron energies, and wherein the moderator has a first trapezidal cross section facing to the beam inlet;

a reflector surrounding the moderator, wherein the reflector leads the neutrons deviated from the main 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.

12. The beam shaping assembly for neutron capture therapy according to claim 11, wherein the moderator has a second trapezidal cross section facing away from the beam inlet and adjioning to the first trapezidal cross section.

13. The beam shaping assembly for neutron capture therapy according to claim 11, wherein all of the beam inlet, the moderator and the beam outlet are extended along the main axis.

14. The beam shaping assembly for neutron capture therapy according to claim 11, wherein the beam shaping assembly includes a gap channel arranged between the moderator and the reflector and enclosed by the reflector, the moderator and the thermal neutron absorber, and wherein the gap channel allows neutron beams to pass for enhancing epithermal neutron beam intensity.

15. The beam shaping assembly for neutron capture therapy according to claim 11, wherein the moderator comprises a recess for receiving the target and at least a part of the beam inlet and the reflector comprises a recess for receiving the other part of the beam inlet.

16. 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, and wherein the neutrons form a neutron beam defining a main axis;

a moderator adjoining to the target, wherein the neutrons are moderated by the moderator to epithermal neutron energies, the moderator includes a first side facing to the beam inlet and a second side facing away from the beam inlet;

a reflector surrounding the moderator, wherein the reflector leads the neutrons deviated from the main 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,

wherein the target is received into the moderator, all of the beam inlet, the moderator and the beam outlet are extended along the main axis, a distance from the target to the beam outlet is closer than a distance from the first side to the beam outlet.

17. The beam shaping assembly for neutron capture therapy according to claim 16, wherein the outer surface of the moderator includes a cylindrical section and a tapered section adjoining to the cylindrical section.

18. The beam shaping assembly for neutron capture therapy according to claim 16, wherein an outer surface of the moderator includes a first single flat tapered section tapered in a first direction away from the beam outlet and a second single flat tapered section adjioning to the first single flat tapered section and tapered in a second direction toward the beam outlet.

19. The beam shaping assembly for neutron capture therapy according to claim 16, wherein the beam shaping assembly includes a gap channel arranged between the moderator and the reflector and enclosed by the reflector, the moderator and the thermal neutron absorber, and wherein the gap channel allows neutron beams to pass for enhancing epithermal neutron beam intensity.

20. The beam shaping assembly for neutron capture therapy according to claim 16, wherein the first side is protruded from the target along a direction from the main axis to the beam inlet and the second side is protruded from the target along a direction from the main axis to the beam outlet.