Beam shaping assembly for neutron capture therapy

Patent metadata

Field	Value
Publication number	US-10617893-B2
Application number	US-201916401328-A
Country	US
Kind code	B2
Filing date	May 2, 2019
Priority date	May 4, 2015
Publication date	Apr 14, 2020
Grant date	Apr 14, 2020

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, 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 material of the moderator is subjected to a powder sintering process using a powder sintering device so as to change powders or a power compact into blocks. The reflector leads the neutrons deviated from the main axis back. 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.

First claim

What is claimed is:

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, the material of the moderator is prepared by mixing a mixture containing one or more of PbF 4 , Al 2 O 3 , AlF 3 , CaF 2 and MgF 2 and a 6 Li element-containing material accounting for 0.1 to 5% in percentage by weight of the mixture;
a reflector surrounding the moderator, wherein the reflector leads the neutrons deviated from the main axis back to enhance epithermal neutron beam intensity;
a radiation shield 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 6 Li element-containing material is 6 LiF or 6 Li 2 CO 3 .

3. The beam shaping assembly for neutron capture therapy according to claim 1 , wherein the material of the moderator is prepared by mixing MgF 2 and a 6 Li element-containing material accounting for 0.1 to 5% in percentage by weight of the MgF 2 .

4. 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 generate nuclear reaction with the target made of a metal material to produce neutrons, wherein the target is received into the moderator, wherein a gap channel for enhancing epithermal neutron beam intensity is arranged between the moderator and the reflector.

5. The beam shaping assembly for neutron capture therapy according to claim 1 , wherein the beam shaping assembly further comprises a thermal neutron absorber for absorbing thermal neutrons so as to avoid overdosing in superficial normal tissue during therapy, the thermal neutron absorber is made of a material having a cross section for acting with thermal neutrons, and the reflector is made of a material having a high neutron reflection ability.

6. The beam shaping assembly for neutron capture therapy according to claim 5 , wherein the reflector is made of at least one of Pb or Ni, the radiation shield comprises photon shield made of Pb and neutron shield made of PE, the thermal neutron absorber is made of 6 Li, 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 an outer surface of the moderator includes at least a tapered section.

8. The beam shaping assembly for neutron capture therapy according to claim 7 , wherein an outer surface of the moderator includes a first tapered section and a second tapered section adjoining to the first tapered section, and a tapering direction of the first tapered section is opposite to a tapering direction of the second tapered section, and wherein the first tapered section includes a first side and a second side facing away from the beam outlet and is tapered gradually from the second side towards the first side, and the second tapered section includes a third side and a fourth side facing the beam outlet and is tapered gradually from the third side towards the fourth side, a distance from the target to the beam outlet is closer than a distance from the first side to the beam outlet.

9. The beam shaping assembly for neutron capture therapy according to claim 8 , wherein the first side defines a first diameter perpendicularly to the main axis, the second side and the third side defines a second diameter perpendicularly to the main axis and the fourth side defines a third diameter perpendicularly to the main axis, the first diameter is 1 cm to 20 cm in length, the second diameter is 30 cm to 100 cm in length, the third diameter is 1 cm to 50 cm in length, and wherein multiple sintered blocks are connected to form the moderator and a density of the moderator is 80 to 100 percent of theoretical density.

10. A beam shaping assembly for neutron capture therapy comprising a moderator for neutrons, wherein the neutrons are moderated by the moderator to epithermal neutron energies, the material of the moderator is prepared by mixing a mixture containing one or more of PbF 4 , Al 2 O 3 , AlF 3 , CaF 2 and MgF 2 and a 6 Li element-containing material accounting for 0.1 to 5% in percentage by weight of the mixture.

11. The beam shaping assembly for neutron capture therapy according to claim 10 , wherein the 6 Li element-containing material is 6 LiF or 6 Li 2 CO 3 .

12. The beam shaping assembly for neutron capture therapy according to claim 11 , wherein the material of the moderator is prepared by mixing MgF 2 and 6 LiF accounting for 0.1 to 5% in percentage by weight of the MgF 2 .

13. The beam shaping assembly for neutron capture therapy according to claim 10 , wherein the moderator is powder sintered block from powders or powder compacts.

14. The beam shaping assembly for neutron capture therapy according to claim 10 , wherein an outer surface of the moderator includes a first tapered section and a second tapered section adjoining to the first tapered section, and a tapering direction of the first tapered section is opposite to a tapering direction of the second tapered section, and wherein the first tapered section includes a first side and a second side facing away from the beam outlet and is tapered gradually from the second side towards the first side, and the second tapered section includes a third side and a fourth side facing the beam outlet and is tapered gradually from the third side towards the fourth side.

15. The beam shaping assembly for neutron capture therapy according to claim 14 , wherein the first side defines a first diameter perpendicularly to the main axis, the second side and the third side defines a second diameter perpendicularly to the main axis and the fourth side defines a third diameter perpendicularly to the main axis, the first diameter is 1 cm to 20 cm in length, the second diameter is 30 cm to 100 cm in length, the third diameter is 1 cm to 50 cm in length, and wherein multiple sintered blocks are connected to form the moderator and a density of the moderator is 80 to 100 percent of theoretical density.

16. The beam shaping assembly for neutron capture therapy according to claim 10 , wherein an outer surface of the moderator includes a cylindrical section and a tapered section adjoining to the cylindrical section.

17. A beam shaping assembly for neutron capture therapy comprising a neutron moderating material, wherein the neutron moderating material is prepared by mixing a mixture containing one or more of PbF 4 , Al 2 O 3 , AlF 3 , CaF 2 and MgF 2 and a 6 Li element-containing material accounting for 0.1 to 5% in percentage by weight of the mixture.

18. The beam shaping assembly for neutron capture therapy according to claim 17 , wherein the 6 Li element-containing material is 6 LiF or 6 Li 2 CO 3 .

19. The beam shaping assembly for neutron capture therapy according to claim 18 , wherein the neutron moderating material is prepared by mixing MgF 2 and 6 LiF accounting for 0.1 to 5% in percentage by weight of the MgF 2 .

20. The beam shaping assembly for neutron capture therapy according to claim 17 , wherein the neutron moderating material is powder sintered block from powders o

Assignees

• Neuboron Medtech Ltd

Inventors

• Liu Yuan-Hao
• Chen Wei-Lin
• Lee Pei-Yi
• Chang Ming-Chuan
• Xu Wenyu

Classifications

• C04B35/6455

  Hot isostatic pressing · CPC title

• C04B35/645

  Pressure sintering · CPC title

• G21G4/02

  Neutron sources · CPC title

• A61N2005/1094

  Shielding, protecting against radiation · CPC title

• A61N5/1042 Primary

  with spatial modulation of the radiation beam within the treatment head · CPC title