Accelerator and medical system and operating method of the same

• US 6,472,834 B2
• Filed: 02/26/2001
• Issued: 10/29/2002
• Est. Priority Date: 07/27/2000
• Status: Expired due to Term

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Nishiuchi, Hideaki, Hiramoto, Kazuo
• Primary Examiner(s): Anderson, Bruce
• Assistant Examiner(s): Wells, Nikita
• Application Number:
  US09/791,697
• Publication Number:
  US 20020014588A1
• Time in Patent Office: 610 Days
• Field of Search: 315/501, 315/507, 315/503, 250/492.3, 250/505.1, 250/396.R
• US Class Current: 315/501
• CPC Class Codes: G21K 5/04 with beam-forming means

Abstract

The accelerator is a cyclic type accelerator having deflection electromagnets and four-pole electromagnets for making a charged particle beam circulate, a multi-pole electromagnet for generating a stability limit of resonance of betatron oscillation for the production of the charged particle beam, and a high frequency source for applying a high frequency electromagnetic field to the beam to move the beam to the outside of the stability limit, thus exciting resonance in the betatron oscillation. The high frequency source generates a sum signal of a plurality of AC signals of which the instantaneous frequencies change with respect to time, and of which the average values of the instantaneous frequencies with respect to time are different, and applies the sum signal via electrodes to the beam.

Claims

1. A cyclic type accelerator comprising:

deflection electromagnets and four-pole electromagnets for making a charged particle beam circulate;

a multi-pole electromagnet for generating a stability limit of resonance of betatron oscillation for emission of said charged particle beam; and

a high frequency source for applying a high frequency electromagnetic field to said beam to move said beam to the outside of said stability limit, thus exciting resonance in said betatron oscillation,

characterized in that, in order to-apply a high frequency electromagnetic field to said beam to move said beam to the outside of said stability limit, said high frequency source generates an AC signal including a plurality of frequency components, between which the minimum frequency difference is in the range from 500 Hz to 10 kHz inclusive, and the phase of the plurality of frequency components is adjusted so that the phase difference between each frequency components take the values other than an integer×

π

.

2. A cyclic type accelerator comprising:

deflection electromagnets and four-pole electromagnets for making a charged particle beam circulate;

a multi-pole electromagnet for generating a stability limit of resonance of betatron oscillation for emission of said charged particle beam; and

a high frequency source for applying a high frequency electromagnetic field to said beam to move said beam to the outside of said stability limit, thus exciting resonance in said betatron oscillation,

characterized in that said high frequency source generates a sum signal of a plurality of signals of which the instantaneous frequencies change with respect to time, and of which the average values of said instantaneous frequencies with respect to time are different, and applies said sum signal to said beam.

3. A cyclic type accelerator comprising:

deflection electromagnets and four-pole electromagnets for making a charged particle beam circulate;

a multi-pole electromagnet for generating a stability limit of resonance of betatron oscillation for emission of said charged particle beam; and

a high frequency source for applying a high frequency electromagnetic field to said beam to move said beam to the outside of said stability limit, thus exciting resonance in said betatron oscillation,

characterized in that said high frequency source generates a sum signal of a plurality of signals of which the instantaneous frequencies change with respect to time, and of which the average values of said instantaneous frequencies with respect to time and values changing with respect to time are different, and applies said sum signal to said beam.

4. A cyclic type accelerator comprising:

deflection electromagnets and four-pole electromagnets for making a charged particle beam circulate;

a multi-pole electromagnet for generating a stability limit of resonance of betatron oscillation for emission of said charged particle beam; and

a high frequency source for applying a high frequency electromagnetic field to said beam to move said beam to the outside of said stability limit, thus exciting resonance in said betatron oscillation,

characterized in that said high frequency source generates a sum signal, Σ

A_i sin(2π

f_it+θ

_i(t)) where t is time, of a plurality of AC signals, A_i sin(2π

f_it+θ

_i(t)) that have different frequencies f_i (i=1, 2 . . . n), signals θ

_i(t) associated with the frequencies f_i and changing with a predetermined period with respect to time, and amplitudes A_i associated with the frequencies f_i.

5. A cyclic type accelerator comprising:

deflection electromagnets and four-pole electromagnets for making a charged particle beam circulate;

a multi-pole electromagnet for generating a stability limit of resonance of betatron oscillation for emission of said charged particle beam; and

a high frequency source for applying a high frequency electromagnetic field to said beam to move said beam to the outside of said stability limit, thus exciting resonance in said betatron oscillation,

characterized in that said high frequency source has a plurality of thermal noise generators, switching means for selecting one of said plurality of thermal noise generators so that the output from said selected thermal noise generator can be applied to said beam, and control means for controlling said switching means to switch said thermal noise generators, thereby selecting a proper one in the course of beam emission.

6. A medical accelerator system comprising:

a cyclic type accelerator having deflection electromagnets and four-pole electromagnets for making a charged particle beam circulate, a multi-pole electromagnet for generating a stability limit of resonance of betatron oscillation for emission of said charged particle beam, and a high frequency source for applying a high frequency electromagnetic field to said beam to move said beam to the outside of said stability limit, thus exciting resonance in said betatron oscillation;

a transport system for transporting said beam produced from said cyclic type accelerator; and

an irradiator for irradiating said transported beam on patient,

characterized in that, in order to apply a high frequency electromagnetic field to said beam to move said beam to the outside of said stability limit, said high frequency source generates an AC signal including a plurality of frequency components, between which the minimum frequency difference is in the range from 500 Hz to 10 kHz inclusive, and the phase of the plurality frequency components is adjusted so that the phase difference between each frequency components take the values other than an integer×

π

.

7. A medical accelerator system comprising:

a cyclic type accelerator having deflection electromagnets and four-pole electromagnets for making a charged particle beam circulate, a multi-pole electromagnet for generating a stability limit of resonance of betatron oscillation for emission of said charged particle beam, and a high frequency source for applying a high frequency electromagnetic field to said beam to move said beam to the outside of said stability limit, thus exciting resonance in said betatron oscillation;

a transport system for transporting said beam produced from said cyclic type accelerator; and

an irradiator for irradiating said transported beam on patient,

characterized in that said high frequency source generates a sum signal of a plurality of signals of which the instantaneous frequencies change with respect to time, and of which the average values of said instantaneous frequencies with respect to time are different, and applies said sum signal to said beam.

8. A medical accelerator system comprising:

a cyclic type accelerator having deflection electromagnets and four-pole electromagnets for making a charged particle beam circulate, a multi-pole electromagnet for generating a stability limit of resonance of betatron oscillation for emission of said charged particle beam, and a high frequency source for applying a high frequency electromagnetic field to said beam to move said beam to the outside of said stability limit, thus exciting resonance in said betatron oscillation;

a transport system for transporting said beam produced from said cyclic type accelerator; and

an irradiator for irradiating said transported beam on patient,

characterized in that said high frequency source generates a sum signal, Σ

A_i sin(2π

f_it+θ

_i)where t is time, of a plurality of AC signals that have different frequencies f_i (i=1, 2 . . . n), and phases θ

_i and amplitudes A_i associated with the frequencies f_i, said phases θ

_i changing with a predetermined period with respect to time.

9. A method of operating a medical accelerator system that has a cyclic type accelerator including deflection electromagnets and four-pole electromagnets for making a charged particle beam circulate, a multi-pole electromagnet for generating a stability limit of resonance of betatron oscillation for emission of said charged particle beam, and a high frequency source for applying a high frequency electromagnetic field to said beam to move said beam to the outside of said stability limit, thus exciting resonance in said betatron oscillation;

a transport system for transporting said beam produced from said cyclic type accelerator; and

an irradiator for irradiating said transported beam on patient, said method comprising the steps of;

generating from said high frequency source an AC signal including a plurality of frequency components, between which the minimum frequency difference is in the range from 500 Hz to 10 kHz inclusive, and the phase of the plurality of frequency components is adjusted so that the phase difference between each frequency components take values other than an integer×

π

;

applying a high frequency electromagnetic field based on said AC signal to said beam so that said beam can be moved to the outside of said stability limit and produced from said cyclic type accelerator;

transporting said produced beam by said transport system; and

irradiating said beam from said irradiator.

10. A method of operating a medical accelerator system that has a cyclic type accelerator including deflection electromagnets and four-pole electromagnets for making a charged particle beam circulate, a multi-pole electromagnet for generating a stability limit of resonance of betatron oscillation for emission of said charged particle beam, and a high frequency source for applying a high frequency electromagnetic field to said beam to move said beam to the outside of said stability limit, thus exciting resonance in said betatron oscillation;

a transport system for transporting said beam produced from said cyclic type accelerator; and

an irradiator for irradiating said transported beam on patient, said method comprising the steps of;

generating from said high frequency source a sum signal of a plurality of signals of which the instantaneous frequencies change with respect to time, and of which the average values of said instantaneous frequencies with respect to time are different;

applying said sum signal to said beam so that said beam can be produced from said cyclic type accelerator;

transporting said produced beam by said transport system; and

irradiating said beam from said irradiator.

11. A method of operating a medical accelerator system that has a cyclic type accelerator including deflection electromagnets and four-pole electromagnets for making a charged particle beam circulate, a multi-pole electromagnet for generating a stability limit of resonance of betatron oscillation for emission of said charged particle beam, and a high frequency source for applying a high frequency electromagnetic field to said beam to move said beam to the outside of said stability limit, thus exciting resonance in said betatron oscillation;

a transport system for transporting said beam produced from said cyclic type accelerator; and

an irradiator for irradiating said transported beam on patient, said method comprising the steps of;

applying to said beam a sum signal, Σ

A_i sin(2π

f_it+θ

_i)where t is time, of a plurality of AC signals that have different high frequencies f_i (i=1, 2 . . . n), and phases θ

_i and amplitudes A_i associated with the frequencies f_i, said phases θ

_i changing with a predetermined period with respect to time;

transporting said beam produced from said accelerator by applying said high frequency signal to said beam; and

irradiating said beam from said irradiator.