BEAM SHAPING ASSEMBLY FOR NEUTRON CAPTURE THERAPY

• US 20180001112A1
• Filed: 09/14/2017
• Published: 01/04/2018
• Est. Priority Date: 05/04/2015
• Status: Active Grant

• Current Assignee: Neuboron Medtech, Ltd.
• Original Assignee: Neuboron Medtech, Ltd.
• Inventors: LIU, Yuan-hao, CHEN, Wei-lin, LEE, Pei-yi, CHANG, Ming-chuan, XU, Wenyu
• Granted Patent: US 10,328,286 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 5/1042 with spatial modulation of the radiation beam within the treatment head
• CPC Class Codes: A61N 5/1077 Beam delivery systems
• CPC Class Codes: C04B 35/553 based on fluorides
• CPC Class Codes: C04B 35/645 Pressure sintering
• CPC Class Codes: C04B 35/6455 Hot isostatic pressing
• CPC Class Codes: G21G 4/02 Neutron sources
• CPC Class Codes: G21K 5/04 with beam-forming means

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.

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, the material of the moderator is prepared by mixing a mixture containing one or more of PbF₄, Al₂O₃, AlF₃, CaF₂ and MgF₂ and a ⁶Li element-containing material accounting for 0.1 to 5% in percentage by weight of the mixture, and wherein the material of the moderator is subjected to a powder sintering process using a powder sintering device so as to change powders or powder compacts into blocks;

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.

2. 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.

3. The beam shaping assembly for neutron capture therapy according to claim 1, wherein 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.

4. The beam shaping assembly for neutron capture therapy according to claim 3, 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.

5. The beam shaping assembly for neutron capture therapy according to claim 1, 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.

6. The beam shaping assembly for neutron capture therapy according to claim 5, 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.

7. The beam shaping assembly for neutron capture therapy according to claim 1, wherein the powder sintering device is a hot-press sintering device or a spark plasma sintering device, and the powder sintering process is a hot-press sintering process or a spark plasma sintering process.

8. The beam shaping assembly for neutron capture therapy according to claim 7, wherein the hot-press sintering device comprises a heating furnace, a pressing assembly arranged in the heating furnace, a mold, powders or powder compacts loaded in the mold, and a controller for controlling the normal operation of the hot-press sintering device, and the hot-press sintering process comprises the following steps:

filling the mold with a predetermined amount of powders or powder compacts;

starting the hot-press furnace to preset pressure and temperature parameters;

moving the pressing assembly to press the powders or powder compacts in the mold;

controlling the hot-press sintering device by the controller to be under the condition of normal operation; and

switching on power to sinter the powders or powder compacts into blocks.

9. The beam shaping assembly for neutron capture therapy according to claim 7, wherein the spark plasma sintering device comprises a first electrode, a second electrode, a conductive mold arranged between the first electrode and the second electrode, a pulse current generator for providing pulse current for the mold, a pressing assembly with a pressing member for pressing, and a controller for controlling the pulse current generator and the pressing assembly, wherein at least one of the first electrode and the second electrode is moved with respect to the other one and connected to the pressing assembly, so that the powders or powder compacts in the mold are pressed;

and the spark plasma sintering process comprises the following steps;

filling the mold with a predetermined amount of powders or powder compacts;

moving at least one of the first electrode and the second electrode to press the powders or the powder compacts in the mold;

switching on the pulse current generator to conduct electricity to the conductive mold, so that plasma is generated, and thereby the surfaces of the powders or the powder compacts are activated and heat; and

sintering the powders or the powder compacts into blocks.

10. The beam shaping assembly for neutron capture therapy according to claim 9, wherein the spark plasma sintering device further comprises a position measurement system for measuring the position of the pressing member, an atmosphere control system for controlling atmosphere in the mold, a water cooling system for cooling the spark plasma sintering device, and a temperature measurement system for measuring temperature in the spark plasma sintering device, and the spark plasma sintering process further comprises the following steps:

controlling the position measurement system by the controller in order to ensure the normal operation of the position measurement system, controlling the atmosphere control system by the controller in order to ensure that atmosphere in the mold is under the condition of normal operation, controlling the water cooling system by the controller in order to ensure the normal operation of the water cooling system, and controlling the temperature measurement system by the controller in order to ensure that temperature in the spark plasma sintering device is under the condition of normal operation.

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, the material of the moderator is prepared from a material containing at least one of LiF, Li₂CO₃, Al₂O₃, AlF₃, CaF₂ and MgF₂, wherein the material of the moderator is subjected to a powder sintering process using a powder sintering device so as to change powders or powder compacts into blocks;

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 outer surface of the moderator includes the 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.

13. The beam shaping assembly for neutron capture therapy according to claim 12, 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.

14. The beam shaping assembly for neutron capture therapy according to claim 11, wherein the powder sintering device is a hot-press sintering device or a spark plasma sintering device, and the powder sintering process is a hot-press sintering process or a spark plasma sintering process.

15. The beam shaping assembly for neutron capture therapy according to claim 14, wherein the hot-press sintering device comprises a heating furnace, a pressing assembly arranged in the heating furnace, a mold, powders or powder compacts loaded in the mold, and a controller for controlling the normal operation of the hot-press sintering device, and the hot-press sintering process comprises the following steps:

filling the mold with a predetermined amount of powders or powder compacts;

starting the hot-press furnace to preset pressure and temperature parameters;

moving the pressing assembly to press the powders or powder compacts in the mold;

controlling the hot-press sintering device by the controller to be under the condition of normal operation; and

switching on power to sinter the powders or powder compacts into blocks.

16. The beam shaping assembly for neutron capture therapy according to claim 14, wherein the spark plasma sintering device comprises a first electrode, a second electrode, a conductive mold arranged between the first electrode and the second electrode, a pulse current generator for providing pulse current for the mold, a pressing assembly with a pressing member for pressing, and a controller for controlling the pulse current generator and the pressing assembly, wherein at least one of the first electrode and the second electrode is moved with respect to the other one and connected to the pressing assembly, so that the powders or powder compacts in the mold are pressed;

and the spark plasma sintering process comprises the following steps;

filling the mold with a predetermined amount of powders or powder compacts;

moving at least one of the first electrode and the second electrode to press the powders or the powder compacts in the mold;

switching on the pulse current generator to conduct electricity to the conductive mold, so that plasma is generated, and thereby the surfaces of the powders or the powder compacts are activated and heat; and

sintering the powders or the powder compacts into blocks.

17. The beam shaping assembly for neutron capture therapy according to claim 16, wherein the spark plasma sintering device further comprises a position measurement system for measuring the position of the pressing member, an atmosphere control system for controlling atmosphere in the mold, a water cooling system for cooling the spark plasma sintering device, and a temperature measurement system for measuring temperature in the spark plasma sintering device, and the spark plasma sintering process further comprises the following steps:

controlling the position measurement system by the controller in order to ensure the normal operation of the position measurement system, controlling the atmosphere control system by the controller in order to ensure that atmosphere in the mold is under the condition of normal operation, controlling the water cooling system by the controller in order to ensure the normal operation of the water cooling system, and controlling the temperature measurement system by the controller in order to ensure that temperature in the spark plasma sintering device is under the condition of normal operation.

18. 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 from a material containing at least one of LiF, Li₂CO₃, Al₂O₃, AlF₃, CaF₂ and MgF₂, wherein the material of the moderator is subjected to a powder sintering process using a powder sintering device so as to change powders or powder compacts into blocks, and wherein the powder sintering device is a hot-press sintering device or a spark plasma sintering device, and the powder sintering process is a hot-press sintering process or a spark plasma sintering process;

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.

19. The beam shaping assembly for neutron capture therapy according to claim 18, wherein the outer surface of the moderator includes the 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, and 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.

20. The beam shaping assembly for neutron capture therapy according to claim 18, wherein the hot-press sintering device comprises a heating furnace, a pressing assembly arranged in the heating furnace, a mold, powders or powder compacts loaded in the mold, and a controller for controlling the normal operation of the hot-press sintering device, and the hot-press sintering process comprises the following steps:

filling the mold with a predetermined amount of powders or powder compacts;

starting the hot-press furnace to preset pressure and temperature parameters;

moving the pressing assembly to press the powders or powder compacts in the mold;

controlling the hot-press sintering device by the controller to be under the condition of normal operation; and

switching on power to sinter the powders or powder compacts into blocks; and

wherein the spark plasma sintering device comprises a first electrode, a second electrode, a conductive mold arranged between the first electrode and the second electrode, a pulse current generator for providing pulse current for the mold, a pressing assembly with a pressing member for pressing, and a controller for controlling the pulse current generator and the pressing assembly, wherein at least one of the first electrode and the second electrode is moved with respect to the other one and connected to the pressing assembly, so that the powders or powder compacts in the mold are pressed; and

the spark plasma sintering process comprises the following steps;

filling the mold with a predetermined amount of powders or powder compacts;

moving at least one of the first electrode and the second electrode to press the powders or the powder compacts in the mold;

switching on the pulse current generator to conduct electricity to the conductive mold, so that plasma is generated, and thereby the surfaces of the powders or the powder compacts are activated and heat; and

sintering the powders or the powder compacts into blocks.