System and method for layer-wise proton beam current variation

• US 8,445,872 B2
• Filed: 09/02/2011
• Issued: 05/21/2013
• Est. Priority Date: 09/03/2010
• Status: Active Grant

• Current Assignee: Varian Medical Systems Particle Therapy GmbH & Company KG (Siemens AG)
• Original Assignee: Varian Medical Systems Particle Therapy GmbH (Siemens AG)
• Inventors: Behrens, Uwe, Stephani, Thomas
• Primary Examiner(s): Souw, Bernard E
• Application Number:
  US13/224,773
• Publication Number:
  US 20120056099A1
• Time in Patent Office: 627 Days
• Field of Search: 250/396.R, 250/492.1, 250/492.3, 250/492.21, 250/492.22, 250/492.23, 250/505.1, 315/500, 315/502, 378/65
• US Class Current: 250/492.22
• 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 5/1077 Beam delivery systems
• CPC Class Codes: H01J 3/14 Arrangements for focusing or reflecting ray or beam H01J3/02, H01J3/04 take precedence
• CPC Class Codes: H05H 13/005 Cyclotrons
• CPC Class Codes: H05H 2007/122 by electromagnetic means, e.g. RF cavities
• CPC Class Codes: H05H 2277/11 Radiotherapy
• CPC Class Codes: H05H 7/02 Circuits or systems for supplying or feeding radio-frequency energy radio-frequency generators H03B

Abstract

Systems and methods are provided to perform efficient, automatic adjustment of cyclotron beam currents within a wide range for multiple treatment layers within the same patient and treatment session. In one embodiment, efficient adjustment is achieved by using beam current attenuation by an electrostatic vertical deflector installed in the inner center of the cyclotron. The beam current may, for example, be adjusted by the high voltage applied to the electrostatic vertical deflector. In front of each treatment the attenuation curve of the vertical deflector is recorded. Based on this attenuation curve, the vertical deflector voltage for the needed beam current of each irradiation layer is interpolated. With this procedure the beam current could be automatically adjusted in minimal time over a wide range while maintaining a high level of precision.

Claims

1. A proton therapy system, the proton therapy system comprising:

a cyclotron, the cyclotron comprising;

an ion source for producing a proton treatment beam having a beam current;

a plurality of beam path modulators; and

a plurality of beam current modulators,

wherein, the proton treatment beam is automatically directed by the plurality of beam path modulators such that at least a portion of the proton treatment beam travels through the plurality of beam current modulators.

2. The system according to claim 1, wherein the plurality of beam path modulators comprises a plurality of electrostatic vertical deflectors.

3. The system according to claim 2, wherein the plurality of beam path modulators comprises a vertical collimator.

4. The system according to claim 1, wherein the plurality of beam current modulators comprises a plurality a moveable phase slits.

5. The system according to claim 2, wherein the plurality of beam path modulators configurably directs at least a portion of the beam of protons through the plurality of beam current modulators by generating an electric field in the electrostatic vertical deflector.

6. The system according to claim 5, wherein the plurality of beam path modulators configurably directs at least a portion of the beam of protons through the plurality of beam current modulators by causing a deflection in a trajectory of the beam of protons.

7. The system according to claim 6, wherein the deflection in the trajectory of the beam of protons is caused by the generated electric field in a beam path modulator of the plurality of beam path modulators.

8. The system according to claim 1, wherein a plurality of extracted proton beams is generated from the proton treatment beam and applied to a plurality of target treatment layers disposed in a proton therapy patient.

9. The system according to claim 8, wherein the plurality of target treatment layers comprise target layers with varying depths in the proton therapy patient, and wherein the varying depths correspond to a treatment plan for the proton therapy patient.

10. The system according to claim 8, wherein the plurality of extracted proton beams is generated by attenuating the beam current of the proton treatment beam to correspond to the plurality of target treatment layers.

11. The system according to claim 10, wherein the attenuating the beam current is performed by directing varying portions of the proton treatment beam through the plurality of beam current modulators according to pre-determined measurement data.

12. The system according to claim 11, wherein the pre-determined measurement data comprises a data curve which plots a correspondence between a plurality of extracted beam currents generated from attenuating the beam current of the proton treatment beam and a voltage in the plurality of beam path modulators.

13. The system according to claim 12, wherein a proton therapy treatment comprising a plurality of extracted beam currents corresponding to a plurality of target treatment layers is generated by the system and applied to a proton therapy patient by automatically attenuating the beam current of the proton therapy treatment beam according to measurement data comprised in the data curve.

14. A method for applying proton therapy comprising:

generating a beam of protons from an ion source, the beam of protons having a beam current;

directing, via a plurality of beam path modulators, the beam of protons through a plurality of beam current modulators;

conducting a plurality of beam current measurements by performing a plurality of beam current adjustments;

analyzing the plurality of beam current measurements to determine a plurality of settings for the plurality of beam path modulators; and

automatically producing a plurality of desired beam currents by adjusting the plurality of beam path modulators to modify the beam current to conform to the plurality of pre-determined configurations.

15. The method according to claim 14, wherein the plurality of pre-determined configurations correspond to a proton therapy treatment plan for a proton therapy patient.

16. The method according to claim 14, wherein the generating, the directing, the conducting, the analyzing and the producing are performed in a cyclotron.

17. The method according to claim 14, wherein the plurality of beam path modulators comprises a plurality of vertical deflector plates.

18. The method according to claim 17, wherein the plurality of beam path modulators comprises a vertical collimator.

19. The method according to claim 14, wherein the plurality of beam current modulators comprises a plurality of moveable phase slits.

20. The method according to claim 14, wherein the directing the beam of protons through a plurality of beam current modulators is performed by modifying openings of the beam current modulators.

21. The method according to claim 20, wherein automatically producing the plurality of desired beam currents comprises adjusting a configuration of the plurality of beam path modulators to modify the trajectory of the beam of protons such that only a portion of the beam of protons passes through the plurality of beam current modulators.

22. The method according to claim 21, wherein the modifying the trajectory of the beam of protons is performed by generating a voltage in the plurality of beam path modulators.

23. The method according to claim 22, wherein the adjusting a plurality of beam path modulators to modify the trajectory of the beam of protons such that only a portion of the beam of protons passes through the plurality of beam current modulators comprises producing an extracted beam of protons having a beam current corresponding to the portion of the beam of protons which passed through the plurality of beam current modulators.

24. The method according to claim 15, wherein the performing a plurality of beam current adjustments to conduct a plurality of beam current measurements comprises:

configuring the plurality of beam path modulators according to the plurality of pre-determined configurations; and

measuring the beam currents of the proton beam produced when the plurality of beam path modulators is configured according to the plurality of pre-determined configurations.

25. The method according to claim 24, wherein the analyzing the plurality of beam current measurements comprises:

measuring beam currents of the proton beam produced when the plurality of beam path modulators is configured according to the plurality of pre-determined configurations; and

extrapolating the measured beam currents to generate a curve.

26. The method according to claim 25, wherein the automatically producing the plurality of desired beam currents comprises:

receiving the plurality of desired beam currents, the plurality of desired beam currents corresponding to a plurality of target layers in the proton therapy patient; and

determining, on the generated curve, a plurality of beam path modulator configurations that correspond to the plurality of desired beam currents corresponding to the plurality of target layers in the proton therapy patient.

27. The method according to claim 26, wherein the plurality of target layers in a treatment target comprises a plurality of target layers with varying depths disposed in the proton therapy patient.

28. The method according to claim 27, wherein the plurality of target layers with varying depths correspond to a proton therapy plan of the proton therapy patient.

29. The method according to claim 25, wherein the automatically producing the plurality of desired beam currents comprises adjusting the plurality of beam path modulators to conform to the plurality of beam path modulator configurations that correspond to the plurality of desired beam currents.

30. A cyclotron, comprising:

a ion source for producing a beam of protons, the beam of protons having a trajectory and a beam current;

a plurality of electrostatic vertical deflectors with a corresponding vertical collimator for causing a deflection of a trajectory of the beam of protons;

a plurality of phase slits for adjusting a beam current of the beam of protons;

a measuring device for measuring the beam current of a beam of protons produced by the ion source and extracted through the plurality of phase slits,

wherein, the cyclotron is used to perform a proton beam therapy treatment by automatically applying a plurality of beam currents to a target patient, the plurality of beam currents being generated by deflecting, via the plurality of electrostatic vertical deflectors, the trajectory of the beam of protons through the plurality of the vertical collimators and the plurality of phase slits.