Beam shaping assembly for neutron capture therapy

Patent metadata

Field	Value
Publication number	US-10124192-B2
Application number	US-201715825690-A
Country	US
Kind code	B2
Filing date	Nov 29, 2017
Priority date	Dec 8, 2014
Publication date	Nov 13, 2018
Grant date	Nov 13, 2018

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.

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;
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, and a second single flat tapered section adjoining to the first single flat tapered section and tapered in a second direction toward 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 D 2 O, AlF 3 , CaF 2 , Li 2 CO 3 , MgF 2 and Al 2 O 3 .

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 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 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 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.

10. 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.

11. The beam shaping assembly for neutron capture therapy according to claim 10 , wherein the moderator has a second trapezidal cross section facing away from the beam inlet and adjoining to the first trapezidal cross section.

12. The beam shaping assembly for neutron capture therapy according to claim 10 , wherein all of the beam inlet, the moderator and the beam outlet are extended along the main axis.

13. The beam shaping assembly for neutron capture therapy according to claim 10 , 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.

14. The beam shaping assembly for neutron capture therapy according to claim 10 , 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.

15. 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 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; and
wherein an outer surface of the moderator includes a cylindrical section and a tapered section adjoining to the cylindrical section.

16. 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

Assignees

• Neuboron Medtech Ltd

Inventors

• Liu Yuan-Hao
• Lee Pei-Yi

Classifications

• A61N2005/109

  Neutrons · CPC title

• G21G4/02

  Neutron sources · CPC title

• A61N5/1077 Primary

  Beam delivery systems · CPC title

• H05H6/00

  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}) · CPC title

• A61N2005/1094

  Shielding, protecting against radiation · CPC title