Control System for a Particle Accelerator

• US 20140091734A1
• Filed: 09/27/2013
• Published: 04/03/2014
• Est. Priority Date: 09/28/2012
• Status: Active Grant

• Current Assignee: Mevion Medical Systems Incorporated
• Original Assignee: Mevion Medical Systems Incorporated
• Inventors: Gall, Kenneth P., Rosenthal, Stanley, Molzahn, Adam C., Sobczynski, Thomas C.
• Granted Patent: US 9,681,531 B2
• Time in Patent Office: Days
• US Class Current: 315/502
• CPC Class Codes: A61N 2005/1095 Elements inserted into the radiation path within the system, e.g. filters or wedges
• CPC Class Codes: A61N 5/1048 Monitoring, verifying, controlling systems and methods
• CPC Class Codes: A61N 5/1065 Beam adjustment
• CPC Class Codes: A61N 5/1077 Beam delivery systems
• 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

Abstract

An example particle therapy system includes a particle accelerator to output a particle beam, where the particle accelerator includes: a particle source to provide pulses of ionized plasma to a cavity, where each pulse of the particle source has a pulse width corresponding to a duration of operation of the particle source to produce the corresponding pulse, and where the particle beam is based on the pulses of ionized plasma; and a modulator wheel having different thicknesses, where each thickness extends across a different circumferential length of the modulator wheel, and where the modulator wheel is arranged to receive a precursor to the particle beam and is configured to create a spread-out Bragg peak for the particle beam

Claims

1. A particle therapy system comprising:

a particle accelerator to output a particle beam, comprising;

a particle source to provide pulses of ionized plasma to a cavity, each pulse of the particle source having a pulse width corresponding to a duration of operation of the particle source to produce the corresponding pulse, the particle beam being based on the pulses of ionized plasma; and

a modulator wheel having different thicknesses, each thickness extending across a different circumferential length of the modulator wheel, the modulator wheel being arranged to receive a precursor to the particle beam and configured to create a spread-out Bragg peak for the particle beam;

one or more first input/output (I/O) modules operable at a first speed, the one or more first I/O modules being configured to send machine instructions to one or more motor controllers, at least one motor controller for controlling the modulator wheel;

one or more second I/O modules operable at a second speed that is greater than the first speed, at least one of the second I/O modules being configured to send machine instructions to the particle source so that pulse widths of the particle source vary with rotational positions of the modulator wheel.

2. The particle therapy system of claim 1, further comprising;

a therapy control computer programmed to receive prescription information from a hospital, to translate the prescription information to machine information, and to send treatment records to the hospital; and

a master control computer having a real-time operating system, the master control computer programmed to receive machine information from the therapy control computer, to translate the machine information into machine instructions, and send the machine instructions to one or more of the first I/O modules and the second I/O modules.

3. The particle therapy system of claim 2, further comprising an optical fiber over which is monitored a rotational speed and position of the modulator wheel.

4. The particle therapy system of claim 1, wherein the first I/O modules comprise programmable logic controllers (PLC).

5. The particle therapy system of claim 4, wherein at least one of the PLCs is programmed to send machine instructions to motor controllers for controlling a field shaping wheel system for shaping the particle beam prior to output.

6. The particle therapy system of claim 4, wherein at least one of the PLCs is programmed to send machine instructions to a motor controller for controlling a scattering system for collimating the particle beam prior to output.

7. The particle therapy system of claim 4, further comprising:

a radio frequency (RF) system to sweep RF frequencies through the cavity to extract particles from a plasma column produced by the particle source, the RF system comprising a rotating capacitor;

wherein at least one of the PLCs is programmed to send machine instructions to a motor controller that controls the rotating capacitor.

8. The particle therapy system of claim 1, wherein a speed of the first I/O modules is on the order of milliseconds and a speed of the second I/O modules is on the order of one or more hundreds of nanoseconds.

9. The particle therapy system of claim 4, further comprising:

a rotatable gantry on which the particle accelerator is mounted;

wherein at least one of the PLCs is programmed to send machine instructions to a motor controller that controls the rotatable gantry.

10. The particle therapy system of claim 4, wherein two or more of the PLCs are configured to communicate with one another.

11. The particle therapy system of claim 1, wherein the second I/O modules comprise field-programmable gate arrays (FPGA).

12. The particle therapy system of claim 11, further comprising:

a circuit board comprising a microprocessor;

at least one of the FPGAs being on the circuit board and in communication with the microprocessor;

wherein the microprocessor is programmed to communicate with a control computer.

13. The particle therapy system of claim 11, further comprising:

a radio frequency (RF) system to sweep RF frequencies through the cavity to extract particles from a plasma column produced by the particle source;

wherein at least one of the FPGAs comprises an RF control module, the RF control module being configured to receive information about a rotation of the modulator wheel and, based thereon, to coordinate operational aspects of the particle source and the RF system.

14. The particle therapy system of claim 13, wherein coordinating operational aspects of the particle source and the RF system comprises turning the particle source on or off based on a rotational position of the modulator wheel, and turning the RF system on or off based on a rotational position of the modulator wheel.

15. The particle therapy system of claim 14, wherein the RF control module is further configured to send machine instruction to the particle source to turn-on when an RF voltage is at a certain frequency and to turn-off when the RF voltage is at a certain frequency.

16. The control system of claim 14, wherein coordinating operational aspects of the particle source comprises specifying pulse widths during turn-on times of the particle source.

24. The particle therapy system of claim 1, wherein the particle therapy system is configured by including one or more structures to deflect pulses so as to control numbers of pulses that impact different thicknesses of the depth modulator.

17. A particle therapy system comprising:

a particle accelerator to output a particle beam comprised of pulses; and

a depth modulator that is in a path of the particle beam, the depth modulator having a variable thickness and being movable so that the particle beam impacts different thicknesses of the depth modulator at different times;

wherein the particle therapy system is configured to control numbers of pulses that impact different thicknesses of the depth modulator.

18. The particle therapy system of claim 17, wherein movement of the depth modulator is controllable so that different numbers of pulses impact at least two different thicknesses of the depth modulator.

19. The particle therapy system of claim 18, further comprising:

a control system to provide control signals; and

a motor to control movement of the depth modulator in response to the control signals, the movement being rotation that is controllable by the control signals.

20. The particle therapy system of claim 17, wherein output of pulses from the accelerator is controlled so that different numbers of pulses impact at least two different thicknesses of the depth modulator.

21. The particle therapy system of claim 17, wherein the particle accelerator comprises:

a particle source configured to generate a plasma stream from which the pulses are extracted, the plasma stream being generated in response to voltage applied to ionized gas, the voltage being controllable to turn the particle source on and off to control the number of pulses that impact the at least two different thicknesses.

22. The particle therapy system of claim 17, wherein the particle accelerator comprises:

a particle source configured to generate a plasma stream from which the pulses are extracted; and

a radio frequency (RF) source to sweep frequencies and thereby extract one or more pulses from the plasma stream at each frequency sweep;

wherein the RF source is controllable to control numbers of pulses that impact different thicknesses of the depth modulator.

23. The particle therapy system of claim 17, wherein the RF source is controllable to skip one or more frequency sweeps.

25. A particle therapy system comprising:

a particle accelerator to output a particle beam, comprising;

a particle source to provide pulses of ionized plasma to a cavity, each pulse of the particle source having a pulse width corresponding to a duration of operation of the particle source to produce the corresponding pulse, the particle beam being based on the pulses of ionized plasma; and

a modulator wheel having different thicknesses, each thickness extending across a different circumferential length of the modulator wheel, the modulator wheel being arranged to receive a precursor to the particle beam and being configured to create a spread-out Bragg peak for the particle beam;

wherein the particle therapy system is configured so that pulse widths of the particle source vary with rotational positions of the modulator wheel.