Rapid cycling medical synchrotron and beam delivery system

• US 7,432,516 B2
• Filed: 01/24/2006
• Issued: 10/07/2008
• Est. Priority Date: 01/24/2006
• Status: Active Grant

• Current Assignee: Brookhaven Science Associates, LLC (Government of the United States of America)
• Original Assignee: Brookhaven Science Associates, LLC (Government of the United States of America)
• Inventors: Peggs, Stephen G., Brennan, J. Michael, Tuozzolo, Joseph E., Zaltsman, Alexander
• Primary Examiner(s): Berman; Jack I.
• Assistant Examiner(s): Logie; Michael J
• Application Number:
  US11/337,916
• Publication Number:
  US 20070170994A1
• Time in Patent Office: 987 Days
• Field of Search: 250/492.1, 250/492.3, 250/281, 250/290, 250/291, 331/34, 315/503, 315/500, 315/501, 315/507
• US Class Current: 250/492.3
• CPC Class Codes: H05H 13/04 Synchrotrons

Abstract

A medical synchrotron which cycles rapidly in order to accelerate particles for delivery in a beam therapy system. The synchrotron generally includes a radiofrequency (RF) cavity for accelerating the particles as a beam and a plurality of combined function magnets arranged in a ring. Each of the combined function magnets performs two functions. The first function of the combined function magnet is to bend the particle beam along an orbital path around the ring. The second function of the combined function magnet is to focus or defocus the particle beam as it travels around the path. The radiofrequency (RF) cavity is a ferrite loaded cavity adapted for high speed frequency swings for rapid cycling acceleration of the particles.

Claims

1. A medical synchrotron for accelerating particles in a particle beam therapy system, the synchrotron comprising:

a radiofrequency (RF) cavity for accelerating the particles as a beam; and

a plurality of combined function magnets arranged in a ring, each of said combined function magnets performing a first function of bending the particle beam along an orbital path around said ring and a second function of focusing or defocusing the particle beam, wherein said combined function magnets comprise;

an arcuate beam pipe defined by a center of curvature;

two saddle coils arranged on opposite sides of said beam pipe; and

a ferro-magnetic core surrounding said beam pipe and said saddle coils, said core having a structural configuration for providing a magnetic field in said beam pipe which varies in strength in a direction toward said beam pipe center of curvature.

2. A medical synchrotron as defined in claim 1, wherein said plurality of combined function magnets comprises a focusing magnet arranged in sequence with a defocusing magnet, said focusing magnet performing the combined function of bending the particle beam and focusing the particle beam and said defocusing magnet performing the combined function of bending the particle beam and defocusing the particle beam.

3. A medical synchrotron as defined in claim 1, wherein said core has a structural configuration adapted for providing a magnetic field in said beam pipe which becomes weaker in the direction toward said beam pipe center of curvature to form a horizontally focusing combined function magnet.

4. A medical synchrotron as defined in claim 1, wherein said core has a structural configuration adapted for providing a magnetic field in said beam pipe which becomes stronger in the direction toward said beam pipe center of curvature to form a horizontally defocusing combined function magnet.

5. A medical synchrotron as defined in claim 1, wherein said ferro-magnetic core comprises a plurality of upper laminates and a plurality of lower laminates stacked on opposite sides of said beam pipe, said upper and lower laminates having a middle arm terminating at an angled end adjacent said beam pipe, the orientation of said angled ends of said upper and lower laminates providing said varying strength magnetic field in said beam pipe.

6. A medical synchrotron as defined in claim 5, wherein said angled ends of said upper and lower laminates form an angle whose intersection point falls outside an outer arc of said beam pipe with respect to said beam pipe center of curvature to form a focusing combined function magnet.

7. A medical synchrotron as defined in claim 5, wherein said angled ends of said upper and lower laminates form an angle whose intersection point falls inside an inner arc of said beam pipe with respect to said beam pipe center of curvature to form a defocusing combined function magnet.

8. A medical synchrotron as defined in claim 1, wherein said radiofrequency (RF) cavity is a ferrite loaded cavity adapted for high speed frequency swings for rapid cycling acceleration of the particles.

9. A medical synchrotron as defined in claim 8, wherein said ferrite loaded RF cavity is adapted for a frequency swing of from about 1.2 MHz to about 6.0 MHz in about 15-17 ms.

10. A medical synchrotron for accelerating particles in a particle beam therapy system, the synchrotron comprising:

a radiofrequency (RF) cavity for accelerating the particles as a beam; and

a plurality of combined function magnets arranged in a ring, each of said combined function magnets performing a first function of bending the particle beam alone an orbital path around said ring and a second function of focusing or defocusing the particle beam,

wherein said radiofrequency (RF) cavity is a ferrite loaded cavity adapted for high speed frequency swings for rapid cycling acceleration of the particles, and

wherein said ferrite loaded RF cavity comprises;

a housing;

a beam pipe centrally disposed in said housing, said beam pipe having two longitudinal gaps; and

a plurality of ferrite rings associated with each gap surrounding said beam pipe.

11. A method for accelerating particles in a medical synchrotron of a particle beam therapy system, the method comprising the steps of:

steering particles of a particle beam along an orbital path with a plurality of magnets arranged in a ring defining said orbital path; and

applying a tuning current to a ferrite loaded radiofrequency (RF) cavity disposed in said orbital path to achieve a high speed frequency swing for rapid cycling acceleration of the particles in said particle beam,

wherein said ferrite loaded RF cavity comprises;

a housing;

a beam pipe centrally disposed in said housing, said beam pipe having two longitudinal gaps; and

a plurality of ferrite rings associated with each gap surrounding said beam pipe.

12. A method as defined in claim 11, wherein said tuning current is applied to said ferrite loaded RF cavity to achieve a frequency swing of from about 1.2 MHz to about 6.0 MHz in about 15-17 ms.

13. A method as defined in claim 12, wherein said tuning current is applied at a repetition rate of about 30 Hz.

14. A method as defined in claim 11, further comprising the steps of focusing and defocusing said particle beam along said orbital path with said plurality of magnets to provide net strong focusing in both horizontal and vertical planes.

15. A method as defined in claim 14, wherein said steps of steering said particle beam, focusing said particle beam and defocusing said particle beam are performed with a focusing combined function magnet and a defocusing combined function magnet arranged in sequence in said ring, said focusing combined function magnet providing a first function of bending the particle beam and a second function of focusing the particle beam, and said defocusing combined function magnet providing a first function of bending the particle beam and a second function of defocusing the particle beam.

16. A particle beam therapy system comprising:

a source of particles;

a synchrotron for accelerating the particles as a particle beam, said synchrotron including a plurality of combined function magnets arranged in a ring and a ferrite loaded radiofrequency (RF) cavity disposed in said ring, each of said combined function magnets performing a first function of bending the particle beam along an orbital path around said ring and a second function of focusing or defocusing the particle beam and said radiofrequency cavity being adapted for high speed frequency swings for rapid cycling acceleration of the particles;

an injector for transporting particles from said source to said synchrotron;

a patient treatment station including a rotatable gantry for delivering a particle beam to a patient; and

a beam transport system for transporting the accelerated beam from said synchrotron to said patient treatment station,

wherein said ferrite loaded RF cavity comprises;

a housing;

a beam pipe centrally disposed in said housing, said beam pipe having two longitudinal gaps; and

a plurality of ferrite rings associated with each gap surrounding said beam pipe.

17. A particle beam therapy system as defined in claim 16, wherein said ferrite loaded RF cavity is adapted for a frequency swing of from about 1.2 MHz to about 6.0 MHz in about 15-17 ms.

18. A particle beam therapy system as defined in claim 16, wherein said plurality of combined function magnets comprises a focusing magnet arranged in sequence with a defocusing magnet, said focusing magnet performing the combined function of bending the particle beam and focusing the particle beam and said defocusing magnet performing the combined function of bending the particle beam and defocusing the particle beam.

19. A particle beam therapy system comprising:

a source of particles;

a synchrotron for accelerating the particles as a particle beam, aid synchrotron including a plurality of combined function magnets arranged in a ring and a ferrite loaded radiofrequency (RF) cavity disposed in said ring, each of said combined function magnets performing a first function of bending the particle beam along an orbital path around said ring and a second function of focusing or defocusing the particle beam and said radiofrequency cavity being adapted for high speed frequency swings for rapid cycling acceleration of the particles;

an injector for transporting particles from said source to said synchrotron;

a patient treatment station including a rotatable gantry for delivering a particle beam to a patient; and

a beam transport system for transporting the accelerated beam from said synchrotron to said patient treatment station wherein said combined function magnets comprise;

an arcuate beam pipe defined by a center of curvature;

two saddle coils arranged on opposite sides of said beam pipe; and

a ferro-magnetic core surrounding said beam pipe and said saddle coils, said core having a structural configuration for providing a magnetic field in said beam pipe which varies in strength in a direction toward said beam pipe center of curvature.

20. A particle beam therapy system as defined in claim 19, wherein said core has a structural configuration adapted for providing a magnetic field in said beam pipe which becomes weaker in the direction toward said beam pipe center of curvature to form a focusing magnet.

21. A particle beam therapy system as defined in claim 19, wherein said core has a structural configuration adapted for providing a magnetic field in said beam pipe which becomes stronger in the direction toward said beam pipe center of curvature to form a defocusing magnet.

22. A particle beam therapy system as defined in claim 19, wherein said ferro-magnetic core comprises a plurality of upper laminates and a plurality of lower laminates stacked on opposite sides of said beam pipe, said upper and lower laminates having a middle arm terminating at an angled end adjacent said beam pipe, the orientation of said angled ends of said upper and lower laminates providing said varying strength magnetic field in said beam pipe.

23. A particle beam therapy system as defined in claim 22, wherein said angled ends of said upper and lower laminates form an angle whose intersection point falls outside an outer arc of said beam pipe with respect to said beam pipe center of curvature to form a focusing magnet.

24. A particle beam therapy system as defined in claim 22, wherein said angled ends of said upper and lower laminates form an angle whose intersection point falls inside an inner arc of said beam pipe with respect to said beam pipe center of curvature to form a defocusing magnet.