PARTICLE BEAM IRRADIATION SYSTEM AND PARTICLE BEAM IRRADIATION METHOD

• US 20120199757A1
• Filed: 10/01/2010
• Published: 08/09/2012
• Est. Priority Date: 11/10/2009
• Status: Active Grant

• Current Assignee: Mitsubishi Electric Corporation
• Original Assignee: Mitsubishi Electric Corporation
• Inventors: Pu, Yuehu
• Granted Patent: US 8,525,133 B2
• Time in Patent Office: Days
• US Class Current: 250/396.R
• CPC Class Codes: A61N 2005/1087 Ions; Protons
• CPC Class Codes: A61N 5/1042 with spatial modulation of the radiation beam within the treatment head
• CPC Class Codes: A61N 5/1043 Scanning the radiation beam, e.g. spot scanning or raster scanning
• CPC Class Codes: G21K 1/087 by electrical means
• CPC Class Codes: G21K 1/093 by magnetic means
• CPC Class Codes: G21K 5/04 with beam-forming means

Abstract

A particle beam irradiation system comprising a first deflector having the maximum deflection amount which enables to move a particle beam in one direction to the maximum width of a target and a second deflector having the maximum deflection amount is less than the maximum deflection amount of the first deflector performs a control in which the particle beam is moved by increasing at least a deflection amount of the second deflector when the particle beam is moved, and performs a deflection substitution control in which a deflection of the second deflector is substituted to a deflection of the first deflector by decreasing the deflection amount of the second deflector and changing a deflection amount of the first deflector so as to make a position of the particle beam in the target dwell when the particle beam dwells.

Claims

1. A particle irradiation system, in which scanning is performed by repeating the operation of moving an incident particle beam in at least one direction and making the incident particle beam dwell so as to irradiate the particle beam onto a target, comprising a first deflector having the maximum deflection amount which enables to move the particle beam in one direction to the maximum width of a target;

a second deflector having the maximum deflection amount which enables to move the particle beam in the one direction and whose maximum deflection amount is less than the maximum deflection amount of the first deflector; and

a scanning control apparatus which controls the first deflector and the second deflector,

wherein the scanning control apparatus performs a control in which the particle beam is moved by increasing at least a deflection amount of the second deflector when the particle beam is moved, and performs a deflection substitution control in which a deflection of the second deflector is substituted to a deflection of the first deflector by decreasing the deflection amount of the second deflector and changing a deflection amount of the first deflector so as to make a position of the particle beam in the target dwell when the particle beam dwells.

2. The particle irradiation system according to claim 1, wherein the scanning control apparatus performs a control in which a deflection amount change speed of the second deflector which increases the deflection amount when the particle beam moves is made faster than a deflection amount change speed of the first deflector which changes the deflection amount when the particle beam dwells.

3. The particle irradiation system according to claim 1 or claim 2, wherein the first deflector deflects the particle beam by an electromagnet.

4. The particle irradiation system according to claim 3, wherein the second deflector deflects the particle beam by an electromagnet.

5. The particle irradiation system according to claim 2, wherein the second deflector deflects the particle beam by an electric field.

6. The particle irradiation system according to claim 1, further comprising a beam position monitor which obtains an information of a position of the particle beam which is scanned, wherein a feedback control is added to the control, in which the deflection amount of the second deflector is decreased, by the information from the beam position monitor when the particle beam dwells.

7. The particle irradiation system according to claim 4, wherein the first deflector comprises an excitation coil of an electromagnet and a first power source which supplies a current to the excitation coil and the second deflector comprises the excitation coil of the electromagnet and a second power source which supplies a current to the excitation coil.

8. The particle irradiation system according to claim 4, wherein an electromagnet comprises a first excitation coil and a second excitation coil on the same iron core, the first deflector comprises the first excitation coil and a first power source which supplies a current to the first excitation coil;

and the second deflector comprises the second excitation coil and a second power source which supplies a current to the second excitation coil.

9. The particle irradiation system according to claim 3, wherein the second deflector is disposed at a position which is a particle beam incident side of a deflection electromagnet which deflects a main direction of particle beam traveling so as to guide the particle beam to the target.

10. The particle irradiation system according to claim 3, wherein the system has the configuration of a rotating gantry, the second deflector is disposed at a position which is a particle beam incident side of a deflection electromagnet which is disposed at a most downstream side of a main direction of particle beam traveling of the rotating gantry.

11. A particle beam irradiation method in which a target is irradiated by repeating the operation of moving the particle beam in at least one direction and making the particle beam dwell so as to scan by a first deflector having the maximum deflection amount which enables to move an incident particle beam in the one direction to the maximum width of the target and a second deflector having the maximum deflection amount, which enables to move the particle beam in the one direction, is less than the maximum deflection amount of the first deflector

wherein at least a deflection amount of the second deflector is increased so as to move the particle beam in the target when the particle beam moves, and the deflection amount of the second deflector is decreased and a deflection amount of the first deflector is changed in such a manner that a deflection of the second deflector is gradually substituted to a deflection of the first deflector so as to make a position of the particle beam in the target dwell when the particle beam dwells.

12. The particle beam irradiation method according to claim 11, wherein a deflection amount change speed of the second deflector which increases the deflection amount when a particle beam moves is faster than that of the first deflector which changes the deflection amount when the particle beam dwells.