CONFIGURABLE COLLIMATOR CONTROLLED USING LINEAR MOTORS

• US 20190001153A1
• Filed: 06/29/2018
• Published: 01/03/2019
• Est. Priority Date: 06/30/2017
• Status: Active Grant

• Current Assignee: Mevion Medical Systems Incorporated
• Original Assignee: Mevion Medical Systems Incorporated
• Inventors: Jones, Mark R., Cooley, James
• Granted Patent: US 10,653,892 B2
• Time in Patent Office: Days
• CPC Class Codes: A61N 2005/109 Neutrons
• CPC Class Codes: A61N 5/1045 using a multi-leaf collimator, e.g. for intensity modulated radiation therapy or IMRT
• CPC Class Codes: A61N 5/1047 with movement of the radiation head during application of radiation, e.g. for intensity modulated arc therapy or IMAT
• CPC Class Codes: A61N 5/1081 Rotating beam systems with a specific mechanical construction, e.g. gantries
• CPC Class Codes: G01D 5/26 characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light
• CPC Class Codes: G21K 1/046 varying the contour of the field, e.g. multileaf collimators
• CPC Class Codes: H05H 13/02 Synchrocyclotrons, i.e. frequency modulated cyclotrons
• CPC Class Codes: H05H 7/04 Magnet systems , e.g. undulators, wigglers free-electron laser H01S3/0903; Energisation thereof

Abstract

An example device for trimming a particle beam includes: structures made of material that blocks passage of the particle beam, with the structures being configurable to define an edge that is movable into a path of the particle beam; and linear motors that are controllable to configure the structures to define the edge.

Claims

1. A device for trimming a particle beam, comprising:

structures comprised of material that blocks passage of the particle beam, the structures being configurable to define an edge that is movable into a path of the particle beam such that a first part of the particle beam on a first side of the edge is blocked by the structures and such that a second part of the particle beam on a second side of the edge is not blocked by the structures; and

linear motors that are controllable to configure the structures to define the edge, each of the linear motors comprising a movable component and a stationary component, the stationary component comprising a magnetic field generator to generate a first magnetic field, the movable component comprising one or more coils to conduct current to produce a second magnetic field that interacts with the first magnetic field to cause the moveable component to move relative to the stationary component;

wherein the movable component of each linear motor is connected to, or part of, a corresponding one of the structures such that the corresponding structure moves along with movement with the movable component.

2. The device of claim 1, wherein the magnetic field generator comprises magnets having like poles that are aligned, the one or more coils being at least partly between the magnets.

3. The device of claim 1, further comprising:

one or more processing devices to control the linear motors to configure the structures, the one or more processing devices being controllable to output one or more control signals to control one or more of the linear motors to extend or to retract one or more of the structures to define the edge, the one or more processing devices being at least partly shielded from exposure to environmental neutron radiation impacting the structures and the linear motors during operation of the device.

4. The device of claim 3, wherein the one or more processing devices are shielded from exposure to the environmental neutron radiation by locating the one more processing devices remotely from the structures and the linear motors.

5. The device of claim 3, wherein the one or more processing devices are shielded from exposure to the environmental neutron radiation by locating the one more processing devices in a different room from the structures and the linear motors.

6. The device of claim 3, further comprising:

encoders that are configured to track movement of the structures and to provide information to the one or more processing devices about the movement of the structures.

7. The device of claim 6, wherein the encoders comprise electronic devices that are connected to a same assembly as the structures and the linear motors.

8. The device of claim 7, wherein the encoders comprise one or more of laser sensors, optic sensors, or diode sensors.

9. The device of claim 1, wherein the structures comprise leaves and each magnetic field generator comprises a pair of magnets, each leaf being between a corresponding pair of magnets.

10. The device of claim 1, further comprising:

a first carriage configured to move in a first dimension, the first carriage holding the structures and the linear motors; and

a second carriage configured to move in a second dimension that is different from the first dimension, the first carriage being coupled to the second carriage.

11. The device of claim 1, wherein the structures are movable also in the first dimension relative to, and separate from movement of, the first carriage.

12. The device of claim 10, wherein the structures define a first edge;

wherein the device further comprises;

second structures that are configurable to define a second edge that is movable into a path of the particle beam such that a third part of the particle beam on a first side of the second edge is blocked by the second structures and such that a fourth part of the particle beam on a second side of the second edge is not blocked by the second structures; and

second linear motors that are controllable to configure the second structures to define the second edge; and

wherein the device further comprises a third carriage that is movable in the first dimension and that is coupled to the second carriage, the third carriage holding the second structures and the second linear motors.

13. The device of claim 12, wherein the second structures are movable also in the first dimension relative to, and separate from movement of, the third carriage.

14. The device of claim 12, wherein the first carriage and the third carriage are controllable to trim a single spot of the particle beam, the single spot corresponding to a cross-sectional area of the particle beam.

15. The device of claim 12, wherein the first carriage and the third carriage are controllable to trim an area having a size that covers multiple spots of the particle beam, a spot corresponding to a cross-sectional area of the particle beam.

16. The device of claim 12, wherein the first carriage and the third carriage are configured to move independently.

17. A device to trim a particle beam, comprising:

a first carriage that is movable in a first dimension;

second carriages that are coupled to the first carriage and therefore movable in the first dimension along with the first carriage, each of the second carriages also being movable in a second dimension that is different from the first dimension, a second carriage among the second carriages comprising;

structures comprised of material that blocks passage of the particle beam, the structures being configurable to define an edge that is movable into a path of the particle beam such that a first part of the particle beam on a first side of the edge is blocked by the structures and such that a second part of the particle beam on a second side of the edge is not blocked by the structures; and

linear motors to configure the structures to define the edge, each of the linear motors being controllable to drive a corresponding one of the structures linearly in the second dimension towards, or away from, the second carriage.

18. The device of claim 17, wherein a linear motor among the linear motors comprises a movable component and a stationary component, the stationary component comprising a magnetic field generator to generate a first magnetic field, the movable component comprising one or more coils to conduct current to produce a second magnetic field that interacts with the first magnetic field to cause the moveable component to move relative to the stationary component;

wherein the movable component of the linear motor is connected to, or part of, a corresponding one of the structures such that the corresponding structure moves along with movement with the movable component.

19. The device of claim 18, wherein the magnetic field generator comprises magnets having like poles that are aligned, the one or more coils being at least partly between the magnets.

20. The device of claim 18, further comprising:

one or more processing devices to control the linear motors to configure the structures, the one or more processing devices being controllable to output one or more control signals to control one or more of the linear motors to extend or to retract one or more of the structures in the second dimension to define the edge, the one or more processing devices being shielded from exposure to environmental neutron radiation impacting the structures and the linear motors during operation of the device.

21. The device of claim 20, wherein the one or more processing devices are shielded from exposure to the environmental neutron radiation by locating the one more processing devices remotely from the structures and the linear motors.

22. The device of claim 20, wherein the one or more processing devices are shielded from exposure to the environmental neutron radiation by locating the one more processing devices in a different room from the structures and the linear motors.

23. The device of claim 20, further comprising:

encoders that are configured to track movement of the structures and to provide information to the one or more processing devices about the movement of the structures.

24. The device of claim 23, wherein the encoders comprise electronic devices that are more tolerant than the one or more processing devices to exposure to the neutron radiation impacting the structures and the linear motors during operation of the device.

25. The device of claim 24, wherein the encoders comprise one or more of laser sensors, optic sensors, or diode sensors.

26. A particle therapy system comprising:

a particle accelerator to output a particle beam, the particle accelerator generating neutron radiation in an enclosed treatment space during operation;

one or more scanning magnets to move the particle beam relative to an irradiation target in a patient; and

a device to trim the particle beam, the device being between the one or more scanning magnets and the patient, the device comprising;

structures comprised of material that blocks passage of the particle beam, the structures being configurable to define an edge that is movable into a path of the particle beam such that a first part of the particle beam on a first side of the edge is blocked by the structures and such that a second part of the particle beam on a second side of the edge is not blocked by the structures; and

linear motors that are controllable to configure the structures by driving the structures linearly to define the edge; and

one or more processing devices to control operation of the device to trim the particle beam, the one or more processing devices being located in an area that is exposed to less than a specified amount of the neutron radiation.

27. The particle therapy system of claim 26, wherein the area is a room that is external to the enclosed treatment space.

28. The particle therapy system of claim 27, where the enclosed treatment space is at least partly shielded to reduce exposure of the room to the neutron radiation.

29. The particle therapy system of claim 26, wherein a linear motor among the linear motors comprises a movable component and a stationary component, the stationary component comprising a magnetic field generator to generate a first magnetic field, the movable component comprising one or more coils to conduct current to produce a second magnetic field that interacts with the first magnetic field to cause the moveable component to move relative to the stationary component;

wherein the movable component of the linear motor is connected to, or part of, a corresponding one of the structures such that the corresponding structure moves along with movement with the movable component to drive the corresponding structure linearly.

30. The device of claim 29, wherein the magnetic field generator comprises magnets having like poles that are aligned, the one or more coils being at least partly between the magnets.

31. The device of claim 30, further comprising:

encoders that are configured to track movement of the structures and to provide information to the one or more processing devices about the movement of the structures, the encoders being within the enclosed treatment space and subjected to the neutron radiation.

32. The device of claim 31, wherein the encoders comprise one or more of laser sensors, optic sensors, or diode sensors.

33. The device of claim 27, wherein the structures comprise leaves and each magnetic field generator comprises a pair of magnets, each leaf being between a corresponding pair of magnets.

34. The particle therapy system of claim 27, wherein the particle accelerator is a synchrocyclotron;

and

wherein the particle therapy system further comprises a gantry on which at least the synchrocyclotron is mounted, the gantry being movable relative to the patient to move the synchrocyclotron relative to the patient.

35. The particle therapy system of claim 34, wherein the synchrocyclotron comprises:

a voltage source to provide a radio frequency (RF) voltage to a cavity to accelerate particles from a particle source, the voltage source being controlled to sweep the RF voltage over a frequency range in a cycle;

a coil to receive electrical current having one of multiple values and to generate a magnetic field corresponding to the electrical current, the magnetic field for causing the particles to move orbitally within the cavity at an energy that corresponds to the electrical current, the magnetic field being at least 4 Tesla; and

an extraction channel to receive the particles from the cavity and to output the particles received from the cavity to the scanning system, the particles that are output from the cavity having an energy that is based on the electrical current;

wherein the synchrocyclotron is configured to enable setting of the electrical current to one of the multiple values, each of the multiple values corresponding to a different energy at which particles are output from the cavity;

wherein the voltage source is controllable to sweep the RF voltage over a different frequency ranges, each different frequency range corresponding to each different energy at which the particles are output from the cavity.

36. The particle therapy system of claim 27, wherein the synchrocyclotron comprises:

a particle source for holding ionized plasma, the particle source being in a cavity and comprising two parts that are separated at an acceleration region;

a voltage source to provide a radio frequency (RF) voltage to the cavity to accelerate particles from the ionized plasma at a separation region of the particle source, the voltage source being controllable to sweep the RF voltage over a frequency range in a cycle;

a coil to receive electrical current to generate a magnetic field based on the electrical current, the magnetic field for causing the particles to move orbitally within the cavity, the magnetic field in the cavity being a maximum of 4 Tesla or more;

at least one magnetic pole piece, the at least one magnetic pole piece comprising ferromagnetic material that borders the cavity; and

an extraction channel to receive the particles from the cavity and to output the particles received towards the one or more scanning magnets.

37. A device for trimming a particle beam, comprising:

structures comprised of material that blocks passage of the particle beam, the structures being configurable to define an edge that is movable into a path of the particle beam; and

linear motors that are controllable to configure the structures to define the edge.

38. The device of claim 37, further comprising:

one or more processing devices to control the linear motors to configure the structures, the one or more processing devices being controllable to output one or more control signals to control one or more of the linear motors to extend or to retract one or more of the structures to define the edge, the one or more processing devices being at least partly shielded from exposure to environmental neutron radiation impacting the structures and the linear motors during operation of the device.

39. The device of claim 38, wherein the one or more processing devices are shielded from exposure to the environmental neutron radiation by locating the one more processing devices remotely from the structures and the linear motors.

40. The device of claim 38, wherein the one or more processing devices are shielded from exposure to the environmental neutron radiation by locating the one more processing devices in a different room from the structures and the linear motors.

41. The device of claim 38, further comprising:

encoders that are configured to track movement of the structures and to provide information to the one or more processing devices about the movement of the structures.

42. The device of claim 41, wherein the encoders comprise electronic devices that are connected to a same assembly as the structures and the linear motors.

43. The device of claim 42, wherein the encoders comprise one or more of laser sensors, optic sensors, or diode sensors.