Rotatable superconducting cyclotron adapted for medical use

• US 4,507,616 A
• Filed: 03/08/1982
• Issued: 03/26/1985
• Est. Priority Date: 03/08/1982
• Status: Expired due to Term

• Current Assignee: Board of Trustees A Constitutional Corporation Operation Michigan State University
• Original Assignee: The Board of Trustees of Michigan State University (Michigan State University)
• Inventors: Blosser, Henry G., Burleigh, Richard J., Johnson, David A., Riedel, Jack
• Primary Examiner(s): Moore, David K.
• Assistant Examiner(s): WIEDER, KENNETH A
• Application Number:
  US06/355,337
• Time in Patent Office: 1,114 Days
• Field of Search: 328/234, 313/62, 250/306, 250/307, 250/492.3, 250/400
• US Class Current: 315/502
• CPC Class Codes: A61N 2005/109 Neutrons
• CPC Class Codes: A61N 5/10 X-ray therapy; Gamma-ray therapy; Particle-irradiation therapy A61N5/01 takes precedence
• CPC Class Codes: A61N 5/1081 Rotating beam systems with a specific mechanical construction, e.g. gantries
• CPC Class Codes: H05H 13/00 Magnetic resonance accelerators; Cyclotrons strophotrons, turbine tubes H01J25/62
• CPC Class Codes: Y10S 505/88 Inductor

Abstract

A superconducting cyclotron (10) rotatable on a support structure (11) in an arc of about 180° around a pivot axis (A--A) and particularly adapted for medical use is described. The rotatable support structure (13, 15) is balanced by being counterweighted (14) so as to allow rotation of the cyclotron and a beam (12), such as a subparticle (neutron) or atomic particle beam, from the cyclotron in the arc around a patient. Flexible hose (25) is moveably attached to the support structure for providing a liquified gas which is supercooled to near 0° K. to an inlet means (122) to a chamber (105) around superconducting coils (101, 102). The liquid (34) level in the cyclotron is maintained approximately half full so that rotation of the support structure and cyclotron through the 180° can be accomplished without spilling the liquid from the cyclotron. With the coils vertically oriented, each turn of the winding is approximately half immersed in liquid (34) and half exposed to cold gas and adequate cooling to maintain superconducting temperatures in the section of coil above the liquid level is provided by the combination of cold gas/vapor and by the conductive flow of heat along each turn of the winding from the half above the liquid to the half below.

Claims

1. A superconducting cyclotron (10) apparatus including ion source means (110) for providing charged atomic particles to be spirally accelerated in the cyclotron with superconducting coils (101, 102) around iron magnetic poles (110, 100a) and which can be cooled with a liquified gas to near 0°

K., RF generator means (24) connected (119) to dees (106,

     107) for spirally accelerating the charged atomic particles to generate a beam of particles or sub-particles from the spirally accelerated charged particles, the cyclotron including a support structure (11) rotatable around a pivot axis (A--A) for the cyclotron and balanced around the pivot axis by a counterweight (14) on the support structure to thereby change the angle of the beam wherein the beam can be directed towards the axis in an arc defining a plane of rotation of the cyclotron by the support structure, the improvement in the support structure which comprises;

(a) a balance bar (13) with two ends including a counterweight (14) at one end of the balance bar opposite a pivot axis (A--A) and a cross bar (15) member at the other end opposite the counterweight, perpendicular to the balance bar and parallel to the pivot axis for supporting the cyclotron mounted on one end of the cross bar such that the beam can be generated in a plane perpendicular to and in the direction of the pivot axis;

(b) pivot means (16,

     17) supporting the balance bar at the pivot axis of the balance bar with the cyclotron and cross bar balancing the counterweight and with the pivot axis providing a fulcrum such that the balance bar is rotatable in an arc of about 180°

in the plane perpendicular to the pivot axis;

(c) drive means (18) for rotating the balance bar in the arc as the beam is generated; and

(d) flexible hose (25) attached at one end to the cross bar at an opposite end from the cyclotron for providing a liquified gas (34) cooled to near 0°

K. through the hose to the cyclotron through an inlet conduit (122) supported by the cross bar with an opposite end (31) of the hose attached to a fixed base (32) providing a mounting surface (B--B) for the support structure wherein as the cyclotron is moved in the arc the hose bends between the base and cross bar.

2. The apparatus of claim 1 wherein the pivot means is a pivot pin mounted around the pivot axis of the balance bar and wherein holders on the mounting surface support the pin for rotation of the balance bar.

3. The apparatus of claim 2 wherein a circular gear (19) is mounted on an extended end of the pivot pin and wherein a worm gear (20) driven by a motor (m) is mated to the circular gear for rotation of the pin and balance bar.

4. The apparatus of claim 3 wherein the RF generating means (24) is connected through a rotary RF joint (23) and through the pivot pin and inside the balance bar and cross bar to the cyclotron dees.

5. The apparatus of claim 2 wherein the holders are mounted on a concrete pad as the fixed base.

6. The apparatus of claim 1 wherein the counterweight is positioned in an opening (33) in and below the mounting surface of the fixed base.

7. The apparatus of claim 1 wherein a table (35) with legs (37) for vertically and horizontally adjusting a positioning surface for a horizontal patient (P) is mounted above the mounting surface such that selected points of the patient are bombarded with the beam.

8. The apparatus of claim 7 wherein an x-ray unit (40, 41) is moveable on a track (42) across the mounting surface of the fixed base so as to be adjacent the table positioning surface.

9. The apparatus of claim 1 wherein the cyclotron has a vent space in an annular conduit (121) around the inlet conduit and wherein the coils are adapted to be cooled with liquified gas filling up to approximately half of the vessel such that as the cyclotron is rotated in the arc the liquified gas is below the inlet means and is thereby prevented from draining from the cyclotron through the vent space.

10. The apparatus of claim 9 wherein the arc of the cyclotron is less than about 180°

.

11. In a superconducting cyclotron (10) apparatus which generates a beam of high velocity atomic particles or subparticles (12) around and above an object to be irradiated from spirally accelerated charged atomic particles which impinge upon a target (111) to produce the beam, with a window (112) and a collimator (114) on a first side of the cyclotron tangential to the spirally accelerated charged atomic particles for defining the beam (12), including a support structure (11) having a counterweight (14) for the cyclotron rotatable on a pivot axis (A--A) between the cyclotron and counterweight (14) for changing the angle of the beam in an arc of 180°

defining a plane around the axis so that an object beneath the cyclotron can be irradiated around the axis the improvement in the cyclotron which comprises;

inlet means (122) for supplying liquified gas to a vessel (150) with a vent space (121) from the vessel for releasing liquified gas which becomes a gas in operation of the cyclotron adjacent the inlet means and with superconducting coils (101,

     102) in the vessel vertically wound around spaced apart iron poles (100, 100a) which can generate a magnetic field between the poles and which functions to produce the spirally accelerated charged atomic particles with an oscillating electrical field, wherein the inlet means is mounted on a second side of the cyclotron opposite the window and collimator, wherein in use the liquified gas supplied by the inlet means fills up to approximately one-half of the vessel and partially covers each of the coils so that the coils are superconducting such that as the cyclotron is rotated in the arc, the liquified gas is below the inlet means and is thereby prevented from draining from the cyclotron through the vent space.

12. The apparatus of claim 11 wherein the cyclotron is mounted on one end of a cross bar (15) and liquified gas supply means on an opposite end of the cross bar with a first end of a balance bar (13) intermediate the cross bar ends such that the cross bar and balance bar form a T, wherein the balance bar is provided with a counterweight (14) on a second end opposite the first end and wherein bearing members (16, 17) are provided intermediate the first and second balance bar ends mounted on the pivot axis so as to provide a balanced fulcrum between the counterweight and the cyclotron and cross bar.

13. The apparatus of claim 12 wherein flexible hoses (25 and 29) and flexible electrical cables (28) are mounted at the end of the cross bar opposite the cyclotron, wherein one of the hoses provides liquified gas to a rigid conduit supported by the support bar through the inlet means to the cyclotron and the remaining hoses provide another cooling liquid to the cyclotron and wherein the flexible electrical cables provide power to the cyclotron through rigidly mounted electrical supply cables supported by the cross bar.

14. The apparatus of claim 13 wherein the bearing members for the balance bar are mounted on a fixed base (32) providing a mounting surface (B--B) and wherein the flexible hoses and cables are rigidly supported on the mounting surface so as to bend when the cyclotron and cross bar are rotated by the balance bar.

15. The method of using a superconducting cyclotron (10) apparatus which generates a beam of high velocity particles or sub-particles from spirally accelerated charged particles which impinge upon a target to produce the beam with a window (112) and collimator (114) on a first side of the cyclotron tangential to the spirally accelerated charged particles for defining the beam (12), including a support structure (11) for the cyclotron rotatable on a pivot axis in an arc of about 180°

or less for changing the angle of the beam in an arc defining a plane around the axis so that an object beneath the cyclotron can be irradiated by the beam around the axis which comprises;

(a) providing an object (P) to be irradiated such that the beam of high velocity particles irradiates the object as the cyclotron is rotated on the pivot axis;

(b) supplying a liquified gas (34) at near 0°

K. in the cyclotron through an inlet means (122) to a vessel (105) containing vertically oriented superconducting coils (101,

     102) around iron poles for generating a magnetic field in the cyclotron which functions to produce the spirally accelerated charged particles with an oscillating electrical field with a vent space (121) for releasing boiled off liquified gas which becomes a gas during operation of the cyclotron adjacent the inlet means, wherein the inlet means is on a side of the cyclotron opposite the collimator and wherein the liquified gas fills up to approximately half of the vessel and partially covers each of the coils so that the coils are superconducting, such that when the cyclotron is rotated in the arc the liquified gas which remains in the vessel is below the inlet means and is thereby prevented from draining from the cyclotron through the vent space; and

(c) irradiating the object with the beam as the cyclotron is rotated in the arc.

16. The method of claim 15 wherein the object is an animal.

17. The method of claim 16 wherein the animal is human.