COLLIMATOR AND ENERGY DEGRADER

• US 20150174429A1
• Filed: 12/20/2013
• Published: 06/25/2015
• Est. Priority Date: 12/20/2013
• Status: Active Grant

• Current Assignee: Mevion Medical Systems Incorporated
• Original Assignee: Mevion Medical Systems Incorporated
• Inventors: Zwart, Gerrit Townsend, Jones, Mark R.
• Granted Patent: US 9,962,560 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: A61N 2005/1087 Ions; Protons
• 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 5/1043 Scanning the radiation beam, e.g. spot scanning or raster scanning
• CPC Class Codes: A61N 5/1045 using a multi-leaf collimator, e.g. for intensity modulated radiation therapy or IMRT
• CPC Class Codes: A61N 5/1048 Monitoring, verifying, controlling systems and methods
• CPC Class Codes: A61N 5/1077 Beam delivery systems
• CPC Class Codes: A61N 5/1081 Rotating beam systems with a specific mechanical construction, e.g. gantries
• CPC Class Codes: A61N 5/1083 Robot arm beam systems
• CPC Class Codes: G21K 1/046 varying the contour of the field, e.g. multileaf collimators
• CPC Class Codes: G21K 1/10 Scattering devices; Absorbing devices; Ionising radiation filters
• CPC Class Codes: H05H 13/02 Synchrocyclotrons, i.e. frequency modulated cyclotrons
• CPC Class Codes: H05H 2007/004 for modifying beam energy, e.g. spread out Bragg peak devices
• CPC Class Codes: H05H 2007/007 for focusing the beam to irradiation target
• CPC Class Codes: H05H 2007/122 by electromagnetic means, e.g. RF cavities

Abstract

A particle therapy system includes a particle accelerator to output a particle beam; and a scanning system for the particle accelerator to scan the particle beam across at least part of an irradiation target. The scanning system is configured to scan the particle beam in two dimensions that are at an angle relative to a direction of the particle beam. A structure defines an edge. The structure is controllable to move in the two dimensions relative to the irradiation target such that at least part of the structure is between at least part of the particle beam and the irradiation target. The structure includes a material that inhibits transmission of the particle beam.

Claims

1. A particle therapy system comprising:

a particle accelerator to output a particle beam; and

a scanning system for the particle accelerator to scan the particle beam across at least part of an irradiation target, the scanning system being configured to scan the particle beam in two dimensions that are at an angle relative to a direction of the particle beam; and

a structure defining an edge, the structure being controllable to move in the two dimensions relative to the irradiation target such that at least part of the structure is between at least part of the particle beam and the irradiation target, the structure comprising a material that inhibits transmission of the particle beam.

2. The particle therapy system of claim 1, wherein the structure is rotatable at least in the two dimensions so that the edge can be moved between different parts of the irradiation target and the particle beam.

3. The particle therapy system of claim 1, wherein the edge comprises a curve that has a radius that varies on at least one side of the structure.

4. The particle therapy system of claim 1, wherein the curve is a French curve.

5. The particle therapy system of claim 1, wherein the structure defines an aperture and the edge comprises an edge of the aperture.

6. The particle therapy system of claim 1, wherein the structure is movable to track a direction of the particle beam.

7. The particle therapy system of claim 1, wherein the structure comprises multiple elements that are adjustable to vary a size of the edge.

8. The particle therapy system of claim 1, wherein the multiple elements comprise fingers that are individually movable relative to the irradiation target.

9. The particle therapy system of claim 1, wherein the structure is part of a collimator system, the structure comprising a first structure in the collimator system and the edge comprising a first edge;

and

wherein the collimator system comprises a second structure comprising a second edge, the first edge and the second edge being controllable to move along different edges of the irradiation target.

10. The particle therapy system of claim 1, wherein the scanning system comprises at least one magnet to control movement of the particle beam to scan the particle beam, the at least one magnet for generating a magnetic field in response to applied current, the magnetic field affecting the movement.

11. The particle therapy system of claim 1, wherein the scanning system is configured to scan the particle beam more quickly in interior sections of the irradiation target than at edges of the irradiation target.

12. The particle therapy system of claim 1, wherein the particle beam is movable so within an area of a plane at a location of the structure;

and

wherein the structure has an area that is less than the area of the plane.

13. The particle therapy system of claim 12, wherein the structure has an area that is less than half the area of the plane.

14. The particle therapy system of claim 12, wherein the structure has an area that is less than a quarter the area of the plane.

15. The particle therapy system of claim 12, wherein the structure has an area that is less than an eighth the area of the plane.

16. The particle therapy system of claim 1, wherein the structure has an area that is less than ten times a cross-sectional area of the particle beam.

17. The particle therapy system of claim 1, wherein the scanning system is configured to scan the particle beam from different incident angles;

and

wherein the structure is controllable to move based on movement of the particle beam as the particle beam is scanned from different incident angles.

18. The particle therapy system of claim 1, wherein the scanning system comprises:

a magnet to affect a direction of the particle beam to scan the particle beam across at least part of an irradiation target;

a degrader to change an energy of the beam prior to output of the particle beam to the irradiation target, the degrader being down-beam of the magnet relative to the particle accelerator; and

wherein the particle accelerator is a variable-energy device.

19. The particle therapy system of claim 1, wherein the particle accelerator so comprises:

a voltage source to provide a radio frequency (RF) voltage to a cavity to accelerate particles from a plasma column, the cavity having a magnetic field causing particles accelerated from the plasma column to move orbitally within the cavity;

an extraction channel to receive the particles accelerated from the plasma column and to output the received particles from the cavity; and

a regenerator to provide a magnetic field bump within the cavity to thereby change successive orbits of the particles accelerated from the plasma column so that, eventually, particles output to the extraction channel;

wherein the magnetic field is between 4 Tesla (T) and 20 T and the magnetic field bump is at most 2 Tesla.

20. A particle therapy system comprising:

a particle accelerator to output a particle beam;

a scanning system to receive the particle beam from the particle accelerator and to perform scanning of at least part of an irradiation target with the particle beam, the scanning system comprising a structure defining an edge, the structure being controllable to move in the two dimensions and to move based on movement of the particle beam so that the edge is between at least part of the particle beam and the irradiation target, the structure comprising a material that inhibits transmission of the particle beam; and

a gantry on which the particle accelerator and the scanning system are mounted, the gantry being configured to move the particle accelerator and the scanning system around the irradiation target.

21. A particle therapy system comprising:

a synchrocyclotron to output a particle beam;

a magnet to affect a direction of the particle beam to move the particle beam across a cross-section of an irradiation target;

a degrader to change an energy of the particle beam prior to moving the particle beam across the cross-section of the irradiation target, the degrader being down-beam of the magnet relative to the synchrocyclotron; and

one or more processing devices to control movement of the degrader so that the degrader at least partly tracks movement of the particle beam at an irradiation plane.

22. The particle therapy system of claim 21, wherein the particle beam is movable within an area of a plane at a location of the degrader;

and

wherein the degrader has an area that is less than the area of the plane.

23. The particle therapy system of claim 21, wherein the degrader comprises multiple pieces, each piece comprised of beam-energy absorbing material, each piece being movable into a path of the particle beam;

wherein the one or more processing devices are programmed to receive an energy of the particle beam to apply to the irradiation target, and to move one or more of the pieces of the beam-energy absorbing material into the path of the particle beam so that a resulting energy of the particle beam approximates the energy of the particle beam to apply to the irradiation target.

24. The particle therapy system of claim 21, wherein the one or more processing devices are programmed to control movement of the one or more pieces of the beam-energy absorbing material to at least partly track movement of the particle beam.

25. The particle therapy system of claim 22, wherein the degrader has an area that is less than half the area of the plane.

26. The particle therapy system of claim 22, wherein the degrader has an area that is less than one-quarter the area of the plane.

27. The particle therapy system of claim 22, wherein the particle beam has a spot size at a location of the degrader;

and

wherein the degrader has an area that is less than ten times an area of the spot size.

28. The particle therapy system of claim 27, wherein the degrader has an area that is less than twice an area of the spot size.

29. The particle therapy system of claim 21, further comprising:

memory to store a treatment plan, the treatment plan comprising information to define a scanning pattern for the irradiation target, the scanning pattern defining movement of the particle beam in the two dimensions and movement of the degrader so that the degrader at least partly tracks movement of the particle beam.

30. The particle therapy system of claim 21, wherein the synchrocyclotron comprises:

a voltage source to provide a radio frequency (RF) voltage to a cavity to accelerate particles from a plasma column, the cavity having a magnetic field causing particles accelerated from the plasma column to move orbitally within the cavity;

an extraction channel to receive the particles accelerated from the plasma column and to output the received particles from the cavity as part of the particle beam; and

a regenerator to provide a magnetic field bump within the cavity to thereby change successive orbits of the particles accelerated from the plasma column so that, eventually, particles output to the extraction channel;

wherein the magnetic field is between 4 Tesla (T) and 20 T and the magnetic field bump is at most 2 Tesla; and

wherein the synchrocyclotron is a variable-energy device.

31. The particle therapy system of claim 30, wherein the magnet and the degrader are part of a scanning system;

and

wherein the particle therapy system further comprises;

a gantry on which the synchrocyclotron and the scanning system are mounted, the gantry being configured to move the synchrocyclotron and the scanning system around the irradiation target.

32. The particle therapy system of claim 31, wherein the scanning system is a raster scanning system.

33. The particle therapy system of claim 31, wherein the scanning system is a spot scanning system.

34. A particle therapy system comprising:

a particle accelerator to output a particle beam;

a scanning system to receive the particle beam from the synchrocyclotron and to perform scanning of at least part of an irradiation target with the particle beam, the scanning system comprising a degrader to change an energy of the particle beam prior to scanning the at least part of the irradiation target, the degrader being down-beam of the magnet relative to the synchrocyclotron;

one or more processing devices to control movement of the degrader so that the degrader at least partly tracks movement of the particle beam during; and

a gantry on which the particle accelerator and the scanning system are mounted, the gantry being configured to move the synchrocyclotron and the scanning system around the irradiation target.

35. The particle therapy system of claim 34, wherein the particle beam is movable within an area of a plane at a location of the degrader;

and

wherein the degrader has an area that is less than the area of the plane.

36. The particle therapy system of claim 34, wherein the degrader comprises multiple pieces, each piece comprised of beam-energy absorbing material, each piece being movable into a path of the particle beam;

wherein the one or more processing devices are programmed to receive an energy of the particle beam to apply to the irradiation target, and to move one or more of the pieces of the beam-energy absorbing material into the path of the particle beam so that a resulting energy of the particle beam approximates the energy of the particle beam to apply to the irradiation target.

37. The particle therapy system of claim 34, wherein the one or more processing devices are programmed to control movement of the one or more pieces of the beam-energy absorbing material to at least partly track movement of the particle beam.

38. The particle therapy system of claim 35, wherein the degrader has an area that is less than half the area of the plane.

39. The particle therapy system of claim 35, wherein the degrader has an area that is less than one-quarter the area of the plane.

40. The particle therapy system of claim 35, wherein the particle beam has a spot size at a location of the degrader;

and

wherein the degrader has an area that is less than ten times an area of the spot size.

41. The particle therapy system of claim 40, wherein the degrader has an area that is less than twice an area of the spot size.

42. The particle therapy system of claim 34, wherein the particle accelerator is a variable-energy synchrocyclotron.