CHARGED PARTICLE BEAM ACCELERATION METHOD AND APPARATUS AS PART OF A CHARGED PARTICLE CANCER THERAPY SYSTEM

• US 20110180720A1
• Filed: 05/21/2009
• Published: 07/28/2011
• Est. Priority Date: 05/22/2008
• Status: Active Grant

• Current Assignee: Vladimir Yegorovich Balakin
• Original Assignee: Vladimir Yegorovich Balakin
• Inventors: Balakin, Vladimir Yegorovich
• Granted Patent: US 9,058,910 B2
• Time in Patent Office: Days
• US Class Current: 250/396.ML
• CPC Class Codes: A61N 2005/1087 Ions; Protons
• CPC Class Codes: G21K 1/087 by electrical means
• CPC Class Codes: G21K 1/093 by magnetic means
• CPC Class Codes: G21K 1/14 using charge exchange devices, e.g. for neutralising or changing the sign of the electrical charges of beams producing or accelerating neutral particle beams H05H3/00
• CPC Class Codes: H05H 13/04 Synchrotrons
• CPC Class Codes: H05H 7/04 Magnet systems , e.g. undulators, wigglers free-electron laser H01S3/0903; Energisation thereof
• CPC Class Codes: H05H 7/08 Arrangements for injecting particles into orbits
• CPC Class Codes: H05H 7/10 Arrangements for ejecting particles from orbits

Abstract

The invention comprises a charged particle beam acceleration method and apparatus used as part of multi-axis charged particle radiation therapy of cancerous tumors. The accelerator includes a synchrotron having advances in turning magnets, edge focusing magnets, magnetic field concentration magnets, and extraction and intensity control elements that minimize the overall size of the synchrotron, provide a tightly controlled proton beam, directly reduce the size of required magnetic fields, directly reduces required operating power, and allows independent energy and intensity control of extracted charged particles from the synchrotron.

Claims

1. An apparatus for tumor therapy using charged particles, the charged particles accelerated by a rounded corner polygon synchrotron, said synchrotron comprising:

a center; and

a charged particle circulation beam path running;

about said center;

through straight sections; and

through turning sections,

wherein each of said turning sections comprises a plurality of bending magnets,

wherein said circulation beam path comprises a length of less than sixty meters, and

wherein a number of said straight sections equals a number of said turning sections.

2. The apparatus of claim 1, further comprising:

a first focusing edge;

a second focusing edge;

a third focusing edge; and

a fourth focusing edge,

wherein a first of said turning sections comprises a first bending magnet and a second bending magnet,

wherein said first bending magnets terminates on opposite sides with said first focusing edge and said second focusing edge,

wherein a first plane established by said first focusing edge intersects a plane established by said second focusing edge beyond said center of said synchrotron,

wherein said second bending magnets terminates on opposite sides with said third focusing edge and said fourth focusing edge,

wherein a second plane established by said third focusing edge intersects a plane established by said fourth focusing edge beyond said center of said synchrotron,

wherein all of said first focusing edge;

said second focusing edge;

said third focusing edge; and

said fourth focusing edge bend the charged particles toward said center of said synchrotron.

3. The apparatus of claim 2, wherein at least two of said plurality of bending magnets further comprise a magnetic field focusing section, said focusing section comprising:

a geometry tapering from a first cross-sectional area to a second cross-sectional area, said second cross-sectional area comprising less than two-thirds of an area of said first cross-sectional area, said second cross-sectional area proximate said charged particle beam path.

4. The apparatus of claim 3, wherein said geometry carries a magnetic field during use, wherein the magnetic field concentrates in density from said first cross-sectional area to said second-cross-sectional area.

5. The apparatus of claim 4, wherein said second cross-sectional area comprises a flat surface, said flat surface comprising about a zero to three microns polish.

6. The apparatus of claim 1, wherein said turning sections each comprise at least four bending magnets, said four bending magnets comprising at least eight edge focusing surfaces, wherein geometry of said edge focusing surfaces focuses the charged particles in said charged particle circulation beam path during use.

7. The apparatus of claim 1, wherein each of said turning sections turns the charged particles by about ninety degrees.

8. The apparatus of claim 7, wherein each of said turning sections comprises at least four focusing edges, wherein geometry of said focusing edges yield an edge focusing effect on the charged particles.

9. The apparatus of claim 8, said bending magnets comprising a tapered core, said tapered core comprising a first cross-section distance at least one and a half times longer than a second cross-section distance, said second cross-section distance proximate a gap, said gap having a surface polish of less than about ten microns roughness, said charged particle circulation beam path running through said gap.

10. The apparatus of claim 1, wherein said number of turning sections comprises exactly four turning sections, wherein each of said four turning sections turns the charged particle circulation beam path about ninety degrees, said synchrotron capable of accelerating the charged particles to at least 300 MeV.

11. The apparatus of claim 10, wherein said four turning sections comprise at least thirty-two charged particle edge focusing surfaces.

12. The apparatus of claim 1, wherein said turning sections comprise at least eight bending magnets, wherein said charged particle circulation beam path does not pass through any operational quadrupole magnets.

13. The apparatus of claim 1, each of said turning magnets comprising:

a gap, said charged particle beam path running through said gap, and

a core, wherein said core terminates at said gap with a surface comprising a finish of less than about ten microns polish.

14. The apparatus of claim 13, further comprising:

a winding coil winding about said core; and

a correction coil winding about said core, wherein said correction coil operates at less than three percent of the power of said winding coil.

15. The apparatus of claim 14, further comprising:

an extraction control algorithm, said extraction control algorithm receiving input generated by a current originating at an extraction foil, said extraction foil proximate said charged particle circulation beam path, said extraction control algorithm comparing a feedback input to an irradiation plan, said extraction control algorithm adjusting a radio-frequency field in a radio-frequency cavity system.

16. The apparatus of claim 1, wherein at least one of said turning magnets further comprises:

a gap through which said charged particle circulation beam path runs; and

an amplifier geometry, wherein said amplifier geometry concentrates a magnetic field approaching said gap.

17. The apparatus of claim 16, further comprising:

a magnetic winding comprising a coil wrapped around at least two of said turning magnets; and

a correction winding comprising a correction coil wrapped about said at least two of said turning magnets, wherein said correction winding operates at less than three percent of the power of said magnetic winding.

18. The apparatus of claim 1, further comprising:

a winding coil, wherein a turn in said coil wraps around at least two of said turning magnets, wherein said turn does not occupy space directly between said at least two of said turning magnets.

19. The apparatus of claim 18, further comprising:

a correction coil wrapped about said at least two turning magnets, wherein said correction coil comprises a turn that does not occupy space directly between said at least two of said turning magnets, wherein said correction coil operates at less than three percent of the power of said winding coil.

20. The apparatus of claim 1, further comprising:

a negative ion source, said negative ion source producing negative ions in a negative ion beam;

an ion beam focusing lens focusing the negative ion beam; and

a converting foil, said converting foil converting the negative ion beam into the charged particles.

21. The apparatus of claim 20, wherein said lens comprises field lines running, in a vacuum system, through the negative ion beam, wherein the field lines focus the negative ion beam, said ion beam focusing lens further comprising:

a first focusing electrode circumferentially surrounding the negative ion beam; and

a second focusing electrode comprising metal conductive paths at least partially blocking the negative ion beam,

wherein first electric field lines run between said first focusing electrode and said second focusing electrode, and

wherein the negative ions encounter first force vectors running up the first electric field lines that focus the negative ion beam.

22. The apparatus of claim 21, wherein said metal conductive paths comprise any of:

a series of conductive lines running substantially in parallel across the negative ion beam;

a conductive grid crossing the negative ion beam; and

a focusing foil crossing the negative ion beam, said focusing foil having holes, said holes comprising a combined cross-sectional area of at least ninety percent of the cross-sectional area of the negative ion beam.

23. The apparatus of claim 20, wherein said converting foil converts the negative ions into the charged particles, wherein said converting foil provides a vacuum barrier between said negative ion source and said charged particle circulation beam path.

24. The apparatus of claim 20, wherein said converting foil provides a pressure seal between said ion beam focusing lens and said turning sections, wherein a first pump system operates to maintain a first vacuum within said ion beam focusing lens, wherein a second pump system operates to maintain a second vacuum in said charged particle circulation beam path.

25. The apparatus of claim 20, wherein said negative ion source further comprises a magnetic field barrier separating a high energy plasma region from a low temperature plasma zone.

26. The apparatus of claim 20, wherein said converting foil comprises:

a beryllium carbon film, wherein said carbon film comprises a thickness of about thirty to two hundred micrometers, wherein said carbon film forms a vacuum barrier between said negative ion source and said plurality of turning magnets.

27. The apparatus of claim 1, wherein said synchrotron further comprises:

an extraction material;

at least a one kilovolt direct current field applied across a pair of extraction blades; and

a deflector,

wherein the charged particles pass through said extraction material resulting in reduced energy charged particles,

wherein the reduced energy charged particles pass between said pair of extraction blades,

wherein the direct current field redirects the reduced energy charged particles out of said synchrotron through said deflector, and

wherein said deflector yields an extracted charged particle beam.

28. The apparatus of claim 27, further comprising an intensity controller controlling intensity of the extracted charged particles via a feedback control.

29. The apparatus of claim 28, wherein an induced current results from the charged particles passing through said extraction material, wherein the induced current comprises said feedback input to said intensity controller.

31. The method of claim 1, further comprising the step of:

bending the charged particles toward said center of said synchrotron using all of a first focusing edge, a second focusing edge, a third focusing edge, and a fourth focusing edge,

wherein a first of said turning sections comprises a first bending magnet and a second bending magnet,

wherein said first bending magnets terminates on opposite sides with said first focusing edge and said second focusing edge,

wherein a first plane established by said first focusing edge intersects a plane established by said second focusing edge beyond said center of said synchrotron,

wherein said second bending magnets terminates on opposite sides with said third focusing edge and said fourth focusing edge, and

wherein a second plane established by said third focusing edge intersects a plane established by said fourth focusing edge beyond said center of said synchrotron.

32. The method of claim 31, further comprising the step of:

focusing the charged particles using at least two of said plurality of bending magnets that further comprise a magnetic field focusing section, said focusing section comprising;

a geometry tapering from a first cross-sectional area to a second cross-sectional area, said second cross-sectional area comprising less than two-thirds of an area of said first cross-sectional area, said second cross-sectional area proximate said charged particle beam path, wherein said geometry carries a magnetic field during use, wherein the magnetic field concentrates in density from said first cross-sectional area to said second-cross-sectional area.

33. The method of claim 32, wherein said second cross-sectional area comprises a flat surface, said flat surface comprising about a zero to three microns polish.

37. The method of claim 9, said bending magnets comprising a tapered core, said tapered core comprising a first cross-section distance at least one and a half times longer than a second cross-section distance, said second cross-section distance proximate a gap, said gap having a surface polish of less than about ten microns roughness, said charged particle circulation beam path running through said gap.

30. A method for tumor therapy using charged particles, the charged particles accelerated by a rounded corner polygon synchrotron, said method comprising the step of:

accelerating the charged particles in a charged particle circulation beam path running about a center of said synchrotron, said charged particle circulation beam path comprising;

straight sections; and

turning sections,

wherein each of said turning sections comprises a plurality of bending magnets,

wherein said circulation beam path comprises a length of less than sixty meters, and

wherein a number of said straight sections equals a number of said turning sections.

34. The method of claim 30, further comprising the step of:

focusing the charged particles in said charged particle circulation beam path during use with edge focusing surfaces having focusing geometry, wherein said turning sections each comprise at least four bending magnets, said four bending magnets comprising at least eight surfaces having said focusing geometry.

35. The method of claim 30, further comprising the step of:

turning the charged particles about ninety degrees with each of said turning sections.

36. The method of claim 35, wherein each of said turning sections comprises at least four focusing edges, wherein geometry of said focusing edges yield an edge focusing effect on the charged particles.

38. The method of claim 30, further comprising the steps of:

accelerating the charged particles to at least 300 MeV using said synchrotron, wherein said number of turning sections comprises exactly four turning sections; and

turning the charge particles about ninety degrees with each of said four turning sections.

39. The method of claim 38, wherein said four turning sections comprise at least thirty-two charged particle edge focusing surfaces.

40. The method of claim 30, wherein said turning sections comprise at least eight bending magnets, wherein said charged particle circulation beam path does not pass through any operational quadrupole magnets.

41. The method of claim 30, further comprising the step of:

running the charged particles through a gap, said gap running through each of said turning magnets, said gap comprising a surface finish of less than about ten microns polish, wherein each of said turning magnets comprises a core terminating at said gap.

42. The method of claim 41, further comprising the step of:

operating a correction coil at less than three percent of the power of a winding coil, said winding coil running about said core, said correction coil winding about said core.

43. The method of claim 42, further comprising the steps of:

an extraction control algorithm comparing an input to an irradiation plan; and

said extraction control algorithm adjusting a radio-frequency in a radio-frequency cavity system, said input comprising a current originating at an extraction foil when the charged particles in said charged particle circulation beam path transmit through said extraction foil.

44. The method of claim 30, further comprising the step of:

concentrating a magnetic field approaching a gap using a tapering core geometry, said charged particle circulation beam path running through said gap, said gap present within said bending magnets.

45. The method of claim 44, further comprising the step of:

operating a correction coil at less than three percent of the power of a winding coil, said winding coil comprising a single winding wrapped around at least two of said turning magnets;

said correction coil comprising a single winding wrapped about said at least two of said turning magnets.

46. The method of claim 30, further comprising the steps of:

generating a negative ion beam using a negative ion source;

focusing the negative ion beam using an ion beam focusing lens; and

converting the negative ion beam at a converting foil into the charged particles.

47. The method of claim 46, wherein said lens comprises field lines running through the negative ion beam, wherein the field lines focus the negative ion beam, said ion beam focusing lens further comprising:

a first focusing electrode circumferentially surrounding the negative ion beam; and

a second focusing electrode comprising metal conductive paths at least partially blocking the negative ion beam,

wherein first electric field lines run between said first focusing electrode and said second focusing electrode, and

wherein the negative ions encounter first force vectors running up the first electric field lines that focus the negative ion beam.

48. The method of claim 46, further comprising the step of:

creating a vacuum barrier using said converting foil between said negative ion source and said charged particle circulation beam path.

49. The method of claim 46, further comprising the steps of:

providing a pressure seal between said ion beam focusing lens and said turning sections using said converting foil;

maintaining a first vacuum within said ion beam focusing lens; and

maintaining a second vacuum within said charged particle circulation beam path, wherein said second vacuum comprises a stronger vacuum than said first vacuum.

50. The method of claim 46, further comprising the step of:

maintaining a magnetic field barrier in said negative ion source between a high energy plasma region and a low temperature plasma zone.

51. The method of claim 46, further comprising the step of:

forming a vacuum barrier between said negative ion source and said plurality of turning magnets with said converting foil,

wherein said converting foil consists essentially of atoms having six or fewer protons, and

wherein said film comprises a thickness of about thirty to two hundred micrometers.

52. The method of claim 30, further comprising the step of:

passing the charged particles through said extraction material resulting in reduced energy charged particles; and

applying at least a one kilovolt direct current field across a pair of extraction blades,

wherein the reduced energy charged particles pass between said pair of extraction blades, and

wherein the direct current field redirects the reduced energy charged particles out of said synchrotron through a deflector resulting in extracted charged particles.

53. The method of claim 52, further comprising the step of:

controlling intensity of the extracted charged particles using an intensity controller and a feedback control.

54. The method of claim 53, wherein said feedback control includes an induced current input resulting from said step of passing the charged particles through said extraction material.