Non-continuous particle beam irradiation method and apparatus

• US 20090236545A1
• Filed: 03/20/2008
• Published: 09/24/2009
• Est. Priority Date: 03/20/2008
• Status: Active Grant

• Current Assignee: Varian Medical Systems Particle Therapy GmbH & Company KG (Siemens AG)
• Original Assignee: Accel Instruments GmbH (Bruker Corporation)
• Inventors: Timmer, Jan
• Granted Patent: US 7,919,765 B2
• Time in Patent Office: Days
• US Class Current: 250/492.100
• CPC Class Codes: A61N 2005/1087 Ions; Protons
• CPC Class Codes: A61N 5/10 X-ray therapy; Gamma-ray therapy; Particle-irradiation therapy A61N5/01 takes precedence
• CPC Class Codes: A61N 5/1043 Scanning the radiation beam, e.g. spot scanning or raster scanning
• CPC Class Codes: H05H 13/04 Synchrotrons

Abstract

Method and apparatus are disclosed for treating a non-continuous particle beam produced by an accelerator in order to irradiate a target volume, wherein an irradiation spot located in the target volume is formed from this beam, and wherein the location of the irradiation spot is controlled by location controlling elements. The setting of the location controlling elements may take place in between subsequent particle bunches of the beam, for example.

Claims

1. A method for treating a non-continuous particle beam produced by an accelerator in order to irradiate a target volume, comprising:

forming an irradiation spot located in the target volume from the beam, and controlling a location of the irradiation spot by setting location controlling elements, wherein at least a portion of the setting of one or more of the location controlling elements takes place in between particle bunches of the beam.

2. The method according to claim 1, wherein the location of the irradiation spot is controlled in three dimensions (X-, Y-, Z-direction) by said location controlling elements and wherein the setting of the location controlling elements in three dimensions (X-, Y-, Z-direction) takes place in between subsequent particle bunches.

3. The method according to claim 1, wherein the non-continuous particle beam is produced by an accelerator, whereby the RF-frequency is changed in a cycle.

4. The method according to claim 3, wherein the accelerator includes a synchrocyclotron comprising a radio frequency (RF) system for alternating the accelerating voltage, and wherein the setting of the location controlling elements is synchronized with the RF-frequency cycle.

5. The method according to claim 3, wherein the accelerator includes a synchrocyclotron comprising a radio frequency (RF) system for alternating the accelerating voltage, and wherein the RF-frequency cycle is actively interrupted by a control system to allow sufficient time between the particle bunches to finish the setting of the location controlling elements.

6. The method according to claim 3, wherein the accelerator includes a synchrocyclotron comprising a radio frequency (RF) system for alternating the accelerating voltage, and wherein signals from a current diagnostic means measuring beam current and/or signals from the RF-system of the accelerator are used to detect a period between the bunches.

7. The method according to claim 3, wherein the accelerator includes a synchrocyclotron comprising a radio frequency (RF) system for alternating the accelerating voltage, and wherein time between subsequent bunches is changed by a control system controlling the RF-system of the accelerator and/or an ion source and/or an input deflector.

8. The method according to claim 1, wherein a number of charged particles in at least one bunch is actively controlled.

9. The method according to claim 8, wherein parameters of the accelerator and/or a beam transport system and/or other elements affecting the beam are set such that the number of charged particles in a single bunch approximately matches a total dose needed for a specific voxel.

10. The method according to claim 8, wherein parameters of the accelerator and/or a beam transport system and/or other elements affecting the beam are set such that the number of particles in a single bunch is part of a total dose needed for a specific voxel.

11. The method according to claim 10, wherein each voxel treatment comprises a bunch of a first number of charged particles and is ended with a bunch of a second number of charged particles, wherein the first number is larger than the second number.

12. The method according to claim 10, wherein a dose delivered by each bunch is measured by dose diagnostic means and a control system calculates a desired number of charged particles in a next bunch on the basis of a dose of a preceding-bunch and controls elements affecting the beam accordingly.

13. The method according to claim 1, wherein at least one voxel to be irradiated is irradiated with multiple bunches with varying numbers of charged particles.

14. The method according to claim 13, wherein at least one bunch of multiple bunches irradiated to a specific voxel has a number of charged particles whose percentage of a total dose applied to the voxel is not greater than a desired dose precision.

15. A particle beam irradiation apparatus, comprising:

a charged particle accelerator for producing a non-continuous particle beam;

a beam transport system for transporting the particle beam;

a plurality of location controlling elements for varying a location of an irradiation spot in a target volume; and

a control system controlling the location controlling elements in such way that at least a portion of a setting of one or more of the location controlling elements takes place in between particle bunches.

16. The apparatus according to claim 15 further comprising charge variation means for varying a number of charged particles per bunch of said particle beam.

17. The apparatus according to claim 16, wherein the charge variation means is a deflector located inside a vacuum chamber of the accelerator

18. The apparatus according to claim 17, wherein the deflector is adapted to deflect the beam in a direction normal to an accelerating plane such that part of the beam can be stopped by collimator plates mounted above and/or below the accelerating plane.

19. The apparatus according to claim 17, further comprising an ion source adapted to adjust the number of charged particles per bunch.

20. The apparatus according to claim 17, further comprising a RF-system of the accelerator adapted to adjust the number of charged particles per bunch.

24. The apparatus according to claim 17, wherein the deflector is located in a region of the accelerator where the particles being accelerated still have a limited energy.

21. A method for treating a non-continuous particle beam produced by an accelerator in order to irradiate a target volume, wherein an irradiation spot located in the target volume is formed from the beam, and wherein the beam comprises a plurality of bunches, wherein a number of charged particles in at least one of the plurality of bunches is actively controlled.

22. A method for treating a non-continuous particle beam produced by an accelerator in order to irradiate a target volume, wherein an irradiation spot located in the target volume is formed from the beam, and wherein at least one voxel treatment comprises a bunch of a first number of charged particles and is ended with a bunch of a second number of charged particles, wherein the first number is larger than the second number.

23. A method for treating a non-continuous particle beam produced by an accelerator in order to irradiate a target volume, wherein an irradiation spot located in the target volume is formed from the beam, and wherein at least one of a plurality of voxels to be irradiated is irradiated with multiple bunches that have varying numbers of charged particles.