Charged-particle beam irradiation apparatus, charged-particle beam rotary irradiation system, and charged-particle beam irradiation method

• US 6,268,610 B1
• Filed: 09/02/1998
• Issued: 07/31/2001
• Est. Priority Date: 10/20/1997
• Status: Expired due to Term

• Current Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Original Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Inventors: Pu, Yuehu
• Primary Examiner(s): Arroyo, Teresa M.
• Assistant Examiner(s): SMITH, JOHNNIE L
• Application Number:
  US09/146,036
• Time in Patent Office: 1,063 Days
• Field of Search: 250/492.3, 250/374, 250/492.2, 250/492.1, 250/398
• US Class Current: 250/492.3
• CPC Class Codes: A61N 2005/1087 Ions; Protons
• CPC Class Codes: A61N 5/10 X-ray therapy; Gamma-ray therapy; Particle-irradiation therapy A61N5/01 takes precedence
• CPC Class Codes: A61N 5/1043 Scanning the radiation beam, e.g. spot scanning or raster scanning
• CPC Class Codes: G21K 5/04 with beam-forming means

Abstract

A charged-particle beam irradiation apparatus capable of realizing spot-scanning in which the spot of a beam parallel to the axis of incidence thereof is shifted in two axial directions within a radiation area, and having a compact and lightweight design. A pair of scanning electromagnets, that are linked by linkage frames, generate a scanning field composed of a pair of magnetic fields effective in bending a charged-particle beam by the same angle in mutually opposite directions. Rotation of the apparatus is accomplished by rotary driving gear having the scanning electromagnets mounted thereon and motors. Thus, spot scanning in which the spot of a beam parallel to the axis of incidence thereof is shifted in two axial directions can be realized.

Claims

1. A charged-particle beam irradiation apparatus, comprising:

a scanning field generator for generating a scanning field composed of a pair of fields effective in bending a charged-particle beam by a same angle in mutually opposite directions; and

a rotator for rotating the scanning field generator with an axis of incidence of the charged-particle beam as a center.

2. The charged-particle beam irradiation apparatus according to claim 1, wherein said scanning field generator generates magnetic fields.

3. The charged-particle beam irradiation apparatus according to claim 1, wherein said scanning field generator generates electric fields.

4. A charged-particle beam rotary irradiation system, comprising:

a deflector for deflecting a charged-particle beam so that the charged-particle beam is perpendicular to a radiation plane to be radiated;

a charged-particle beam irradiation apparatus that includes a scanning field generator, located downstream of said deflector, for generating a scanning field composed of a pair of fields effective in bending a charged-particle beam by a same angle in mutually opposite directions, and a rotator for rotating said scanning field generator with an axis of incidence of the charged-particle beam as a center, and that sweeps the charged-particle beam deflected by said deflector for the purpose of scan;

a charged-particle beam energy interposed between said charged-particle beam irradiation apparatus and an irradiated subject; and

a rotary motion device for rotating at least said deflector and charged particle beam irradiation apparatus in one united body.

5. The charged-particle beam rotary irradiation system according to claim 4, wherein said charged-particle beam falls on said deflector from the direction of the axis of rotation of said rotary motion device, and said deflector includes three deflective electromagnets for deflecting an incident charged-particle beam three times by 90°

with respect to a direction parallel to a radiation plane so that the charged-particle beam be perpendicular to the radiation plane, and said irradiated subject is positioned on the axis of rotation of said rotary motion device.

6. The charged-particle beam rotary irradiation system according to claim 5, wherein said deflective electromagnets of said deflector are realized with superconducting electromagnets.

7. A charged-particle beam irradiation system, comprising:

a charged-particle beam irradiation apparatus that includes a scanning field generator for generating a scanning field composed of a pair of fields effective in bending a charged-particle beam by a same angle in mutually opposite directions, and a rotator for rotating said scanning field generator with an axis of incidence of the charged-particle beam as a center, and that sweeps the charged-particle beam for the purpose of scan;

a charged-particle beam energy adjuster, interposed between said charged-particle beam irradiation apparatus and an irradiated subject, for adjusting energy of a charged-particle beam;

a dose/position measuring device, interposed between said charged-particle beam irradiation apparatus and irradiated subject, for monitoring a dose and position of an irradiated charged-particle beam;

a beam stopper for stopping a charged-particle beam;

a controller, for controlling scanning based on one of a number of deposited particles of the charged-particle beam and a number of scanning being carried out.

8. The charged-particle beam irradiation system according to claim 7, wherein said controller includes:

a first means for setting the angle of rotation and field intensity concerning said scanning field generator, and the energy of a charged-particle beam according to a group of coordinates [Pi ;

i=1, 2, . . . , n] (i=1 that is an initial value) defining a radiation area;

a second means for irradiating a charged-particle beam according to the setting;

a third means for, when a number of deposited particles of a charged-particle beam becomes equal to or larger than a pre-set number of particles or when a coordinate of a position to which a charged-particle beam is irradiated is inconsistent with a coordinate of a pre-set position, stopping the charged-particle beam; and

a fourth means that when a charged-particle beam is stopped, judges whether or not irradiation to the whole radiation area is completed, that if the irradiation is not completed, increments i by one, modifies the angle of rotation and field intensity concerning said scanning field generator, and the energy of a charged-particle beam in given order, and thus actuates said first to third means repeatedly, and that if the irradiation is completed, terminates irradiation.

9. The charged-particle beam irradiation system according to claim 8, wherein said fourth means retains the angle of rotation of said scanning field generator at a certain value, modifies the intensity of a field generated by said scanning field generator and the energy of a charged-particle beam in given order, and thus actuates said first to third means repeatedly.

10. The charged-particle beam irradiation system according to claim 7, wherein said controller includes:

a first means for setting the energy of a charged-particle beam to be irradiated according to a coordinate of a position indicating a depth to which a beam is irradiated, Zi (i=1 that is an initial value), specified in a group of coordinates [(Zi, θ

ij), i=1, 2, . . . , m, j=1, 2, . . . , n] defining a radiation area;

a second means for specifying the angle of rotation of said scanning field generator in θ

ij (j=1 that is an initial value) and specifying a set defining a scan pattern that is a characteristic curve relative to time in Iij(t);

a third means for irradiating a charged-particle beam according to the setting and specification, driving said scanning field generator according to the scan pattern that is the characteristic curve relative to time defined by Iij(t), and thus sweeping a charged-particle beam so as to achieve a given number of scans;

a fourth means for judging in parallel with the scans achieved by said third means whether or not a coordinate of a position to which a charged-particle beam is irradiated is consistent with a coordinate of a pre-set position;

a fifth means for, when the given number of scans have been carried out or when the coordinate of the position to which a charged-particle beam is irradiated is inconsistent with the coordinate of the pre-set position, stopping the charged-particle beam; and

a sixth means that when a charged-particle beam is stopped, judges whether or not irradiation to the whole radiation area is completed, that if the irradiation is completed, terminates irradiation, that if the irradiation is not completed, judges whether or not the coordinate of the position indicating a depth to which a beam is irradiated, Zi, should be changed to the next value, that if the coordinate is not changed, increments j by one, and actuates the second to fifth means repeatedly, that if the coordinate is changed, increments i by one, resets j to the initial value 1, and actuates the first to fifth means repeatedly.

11. The charged-particle beam irradiation system according to claim 10, wherein Iij(t)∝

{square root over (t)} is adopted as Iij(t) defining the scan pattern that is the characteristic curve relative to time to be followed by said scanning field generator.