Particle beam treatment system and beam position correcting method thereof

Patent metadata

Field	Value
Publication number	US-9387346-B2
Application number	US-201214346908-A
Country	US
Kind code	B2
Filing date	Sep 21, 2012
Priority date	Nov 8, 2011
Publication date	Jul 12, 2016
Grant date	Jul 12, 2016

Abstract

A particle beam treatment system includes an accelerator system that accelerates a charged particle beam and a beam transport system that transports a high-energy beam emitted from the accelerator to an irradiation location, wherein the beam transport system is provided with at least one steering electromagnet and at least one beam position monitor corresponding to the at least one steering electromagnet, and wherein the at least one beam position monitor supplies an excitation current for correcting a beam position, which periodically varies, to the at least one steering electromagnet.

First claim

The invention claimed is:

1. A particle beam treatment system comprising:
an accelerator system that accelerates a charged particle beam; and
a beam transport system that transports a high-energy beam emitted from an accelerator to an irradiation location,
wherein the beam transport system is provided with two steering electromagnets and two beam position monitors corresponding to the steering electromagnets,
wherein the first beam position monitor is disposed in the front of the second steering electromagnet and is configured to detect beam position variation over a period of time and to supply a first excitation current for correcting a periodic position variation and a periodic angle variation of the beam position based upon the beam position variation detected by the first beam position monitor, to the first steering electromagnet, and
wherein the second beam position monitor is disposed in the back of the second steering electromagnet and is configured to detect beam position variation over the period of time and supply a second excitation current for correcting a periodic position variation and a periodic angle variation of the beam position based upon the beam position variation detected by the second beam position monitor, to the second steering electromagnet.

2. The particle beam treatment system according to claim 1 , wherein the first beam position monitor is disposed in the vicinity of the front of the second steering electromagnet and a third beam position monitor is disposed in the vicinity of the back of the second steering electromagnet, and
wherein a position of the second steering electromagnet is calculated from values measured by the first and third beam position monitors.

3. A beam position correcting method of a particle beam treatment system which includes an accelerator system that accelerates a charged particle beam and a beam transport system that transports a high-energy beam emitted from an accelerator to an irradiation location and in which the beam transport system is provided with at least one steering electromagnet and at least one beam position monitor corresponding to the at least one steering electromagnet, comprising:
detecting a periodic variation of a beam position by applying a beam in a state where the at least one beam position monitor is detachably disposed at an irradiation location in test irradiation;
supplying a value of an excitation current to the at least one steering electromagnet in synchronization with the periodic position variation so as to cancel the periodic variation;
storing a value of the periodic excitation current; and
supplying the stored value of the periodic excitation current to the at least one steering electromagnet in a state where the at least one beam position monitor is detached from the irradiation location in actual irradiation.

4. A beam position correcting method of a particle beam treatment system which includes an accelerator system that accelerates a charged particle beam and a beam transport system that transports a high-energy beam emitted from an accelerator to an irradiation location, comprising:
observing a position variation of a beam periodically accelerated and emitted by a synchrotron by the use of a beam position monitor disposed downstream of a deflection electromagnet in a final stage of the beam transport system;
calculating a beam trajectory of the beam transport system on the basis of the observation result, wherein said calculating takes into account a periodic variation of the beam position;
disposing a steering electromagnet at a position s at which a beam position X 0 ( s ) at the position s when there is no disturbance and a beam position X 1 ( s ) at the position s when there is disturbance are equal to each other, that is, the position at which X 0 ( s )=X 1 ( s ) is satisfied,
acquiring and storing a current pattern in which a beam position does not vary by the use of the beam position monitor by causing a current to flow in the steering electromagnet in test irradiation; and
causing the beam position and a beam angle not to vary by causing a current corresponding to the current pattern to flow in actual irradiation.

5. The beam position correcting method of a particle beam treatment system according to claim 4 , wherein the steering electromagnet is disposed at the position s at which the beam position X 0 ( s ) at the position s when there is no disturbance and the beam position X 1 ( s ) at the position s when there is disturbance are equal to zero, that is, the position at which X 0 ( s )=X 1 ( s )=0 is satisfied.

6. A beam position correcting method of a particle beam treatment system which includes an accelerator system that accelerates a charged particle beam and a beam transport system that transports a high-energy beam emitted from an accelerator to an irradiation location and in which the beam transport system is provided with two steering electromagnets and two beam position monitors disposed in the back of the two steering electromagnets, comprising:
detecting a detection signal X 1 ( t ) of a beam position at each time t by the use of the first beam position monitor;
detecting a detection signal X 2 ( t ) of the beam position at each time t by the use of the second beam position monitor;
calculating a kick angle at each time at which X 1 and X 2 are able to be set to 0;
creating current patterns 11 ( t ) and 12 ( t ) corresponding to the calculated kick angle;
outputting the current patterns as excitation currents of the two steering electromagnets, respectively; and
correcting the beam position so as to be finally located on a beam axis.

7. A beam position correcting method of a particle beam treatment system, wherein the particle beam treatment system comprises an accelerator system that accelerates a charged particle beam and a beam transport system that transports a high-energy beam emitted from an accelerator to an irradiation location, wherein the beam transport system comprises (i) an upstream steering electromagnet and a downstream steering electromagnet and (ii) an upstream beam position monitor disposed between the upstream steering electromagnet and the downstream steering electromagnet and a downstream beam position monitor positioned downstream of the downstream steering electromagnet, the method comprising:
conducting a test irradiation, comprising the steps of
storing current pattern data of the upstream steering electromagnet in which a beam position does not temporally vary,
adjusting a current supplied to the upstream steering electromagnet in accordance with the stored current pattern,
observing the beam position by the downstream beam position monitor while the adjusted current is supplied to the upstream steering electromagnet,
varying the current in the downstream electromagnet,
storing current pattern data of the downstream steering electromagnet in which the beam position does not temporally vary; and

conducting an actual irradiation, wherein the beam position and beam angle are corrected for temporal variation by supplying current to the upstream steering electromagnet and the downstream steering electromagnet in accordance with the respective stored current patterns, in synchronism with the beam spill period of a synchrotron.

8. The beam position correcting method of a particle beam treatment system according to claim 7 , wherein the current pattern data supplied to the downstream steering electromagnet comprises a correction current pattern signal including a periodic error variation of devices and/or a periodic error variation due to devices based on a respiration-synchronized signal.

Assignees

• Mitsubishi Electric Corp

Inventors

• Hanakawa Kazushi
• Sugahara Kengo
• ODAWARA Shuhei
• Harada Hisashi
• Ikeda Masahiro
• Otani Toshihiro
• Honda Taizo
• Yoshida Katsuhisa

Classifications

• H05H7/04

  Magnet systems {, e.g. undulators, wigglers (free-electron laser H01S3/0903)}; Energisation thereof · CPC title

• A61N5/1043 Primary

  Scanning the radiation beam, e.g. spot scanning or raster scanning · CPC title

• H05H2277/11

  Radiotherapy · CPC title

• H05H2007/048

  for modifying beam trajectory, e.g. gantry systems · CPC title

• A61N5/1042 Primary

  with spatial modulation of the radiation beam within the treatment head · CPC title