MRI MAGNET FOR RADIATION AND PARTICLE THERAPY

• US 20140128719A1
• Filed: 11/05/2013
• Published: 05/08/2014
• Est. Priority Date: 11/06/2012
• Status: Active Grant

• Current Assignee: Siemens Healthineers AG (Siemens AG)
• Original Assignee: Siemens AG
• Inventors: Longfield, Matthew John
• Granted Patent: US 10,061,000 B2
• Time in Patent Office: Days
• US Class Current: 600/411
• CPC Class Codes: G01R 33/3815 with superconducting coils, e.g. power supply therefor
• CPC Class Codes: G01R 33/4808 Multimodal MR, e.g. MR combined with positron emission tomography [PET], MR combined with ultrasound or MR combined with computed tomography [CT]

Abstract

In an MRI magnet structure for use with a radiation beam source as an assembly, magnet coils of varying diameters are concentrically arranged along a magnetic axis, the magnetic coils not sharing a common inner or outer radius. Mechanical support is provided to retain the magnetic coils in necessary relative fixed positions. The patient bore tube is provided through the assembly and defines a patient bore axis in an essentially horizontal direction such that the magnetic axis is inclined to the patient bore axis by an angle of 30°-60°. At least one radiation therapy beam access cavity provides access in a straight line for a radiation therapy beam to reach a treatment region within the magnet structure.

Claims

1. An MRI magnet structure for use with a radiation beam source as an assembly in combined MRI/radiation therapy, comprising:

magnet coils of varying diameters concentrically arranged along a magnet axis, wherein the magnet coils do not share a common inner or outer radius;

mechanical support to retain the magnet coils in necessary relative fixed positions;

a patient bore tube provided through the assembly and defining a patient bore axis in an essentially horizontal direction such that said magnet axis is inclined to the patient bore axis by an angle of 30°

-60°

; and

at least one radiation therapy beam access cavity providing access in a straight line for a radiation therapy beam to reach a treatment region within the magnet structure.

2. The MRI structure according to claim 1 further comprising a patient bed to enable transport of patients into and out of the patient bore tube.

3. The MRI structure according to claim 1 wherein the radiation therapy beam access cavity is approximately perpendicular to the patient bore tube.

4. The MRI structure according to claim 3 wherein both the patient bore tube and the radiation therapy beam access cavity extend at an angle of approximately 45°

to the magnet axis.

5. The MRI structure according to claim 1 wherein the magnet coils are superconducting, and the MRI magnet structure further comprises an outer vacuum container enclosing the magnet coils within a vacuum, and at least one thermal radiation shield between the coils and the outer vacuum container.

6. The MRI structure according to claim 1 wherein the magnet coils are superconducting, and the MRI magnet structure further comprises a cryogen vessel enclosing the magnet coils within a cryogen atmosphere, an outer vacuum container enclosing the cryogen vessel in a vacuum and at least one thermal radiation shield between the cryogen vessel and the outer vacuum container.

7. The MRI structure according to claim 5 wherein the outer vacuum container has rotational symmetry about the patient axis.

8. The MRI structure according to claim 5 wherein the outer vacuum container has rotational symmetry about the magnet axis.

9. The MRI structure according to claim 3 in which both the magnet axis and the patient axis are horizontal, and beam access cavities are provided at opposite sides of the outer vacuum container.

10. The MRI structure according to claim 3 in which beam access cavities are provided at upper and lower sides of the outer vacuum container.

11. A combined MRI and radiation therapy apparatus, comprising:

an MRI magnet structure, comprising

magnet coils of varying diameters concentrically arranged along a magnet axis, wherein the magnet coils do not share a common inner or outer radius,

mechanical support to retain the magnet coils in necessary relative fixed positions,

a patient bore tube provided through the assembly and defining a patient bore axis in an essentially horizontal direction such that said magnet axis is inclined to the patient bore axis by an angle of 30°

-60°

, and

at least one radiation therapy beam access cavity providing access in a straight line for a radiation therapy beam to reach a treatment region within the magnet structure; and

a radiation therapy beam source arranged to rotate around the magnet structure about the patient axis and to direct the radiation therapy beam through the at least one beam access cavity towards the treatment region.

12. A combined MRI and radiation therapy apparatus, comprising:

an MRI magnet structure and a radiation therapy particle beam source as an assembly;

the MRI magnet structure comprises

magnet coils of varying diameters concentrically arranged along a magnet axis, wherein the magnet coils do not share a common inner or outer radius,

mechanical support to retain the magnet coils in necessary relative fixed positions, and

a patient bore tube provided through the assembly and defining a patient bore axis in an essentially horizontal direction such that the magnet axis is inclined to the patient bore axis by an angle of 30°

-60°

; and

said charged particle source being directed along the magnet axis.

13. The combined MRI and radiation therapy apparatus according to claim 12 further comprising at least one radiation therapy beam access cavity providing access in a straight line for a radiation beam to reach a treatment region within the magnet structure.

14. The combined MRI and radiation therapy apparatus according to claim 12 wherein the magnet coils are superconducting, the MRI magnet structure further comprises an outer vacuum container enclosing the magnet coils within a vacuum, and at least one thermal radiation shield between the coils and the outer vacuum container.

15. The MRI structure according to claim 14 wherein the outer vacuum container has rotational symmetry about the patient axis.

16. The MRI structure according to claim 14 wherein the outer vacuum container has rotational symmetry about the magnet axis.

17. The combined MRI and radiation therapy apparatus according to claim 14 wherein the charged particle source is directed through the material of the outer vacuum container and the at least one thermal radiation shield.

18. The combined MRI and radiation therapy apparatus according to claim 17 wherein windows of material transparent to charged particles emitted by the charged particle source are provided in an otherwise non-transparent outer vacuum container and thermal radiation shield for passage of charged particles emitted by the charged particle source.

19. The combined MRI and radiation therapy apparatus according to claim 14 wherein a through-cavity is provided to allow passage of charged particles from the charged particle source along the magnet axis without traversing the outer vacuum container or the at least one thermal radiation shield.

20. An MRI magnet structure for use with a radiation beam source as an assembly in combined MRI/radiation therapy, comprising:

magnet coils of varying diameters concentrically arranged along a magnet axis, wherein the magnet coils do not share a common inner or outer radius;

mechanical support to retain the magnet coils in necessary relative fixed positions;

a patient bore tube provided through the assembly and defining a patient bore axis in an essentially horizontal direction and aligned with the magnet axis; and

at least one radiation therapy beam access cavity inclined to the patient bore axis by an angle of 30°

-60° and

providing access in a straight line for a radiation beam to reach a treatment region within the magnet structure.

21. The MRI magnet structure according to claim 20 wherein beam access cavities are provided inclined at an angle of approximately 45°

to the magnet axis and the patient bore axis.

22. The MRI magnet structure according to claim 20 wherein beam axis cavities extend around the magnet and patient axes by a significant angle to give a range of available angles of incidence of the radiation beam at the treatment region.