PARTICLE BEAM THERAPY SYSTEM

• US 20110260074A1
• Filed: 01/28/2010
• Published: 10/27/2011
• Est. Priority Date: 01/28/2010
• Status: Active Grant

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Mitsubishi Electric Corporation
• Inventors: Harada, Hisashi, Yamamoto, Yuichi, Pu, Yuehu, Iwata, Takaaki, Honda, Taizo
• Granted Patent: US 8,405,042 B2
• Time in Patent Office: Days
• US Class Current: 250/396.00R
• 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: A61N 5/1048 Monitoring, verifying, controlling systems and methods

Abstract

The objective of the present invention is to reduce the effect of the hysteresis of a scanning electromagnet so as to obtain a particle beam therapy system that realizes high-accuracy beam irradiation. There are included an irradiation management apparatus (32) that controls the scanning electromagnet (3), based on target irradiation position coordinates (Pi) of a charged particle beam (1b), and a position monitor (7) that measures measurement position coordinates (Ps) of the charged particle beam (1b). The irradiation management apparatus (32) has a command value creator (25) that outputs a control input (Io (Ir)) to the scanning electromagnet (3), based on the target irradiation position coordinates (Pi) and correction data (Ia) created on the basis of the measurement position coordinates (Ps), measured by the position monitor (7) in the preliminary irradiation in which the excitation pattern of the scanning electromagnet is the same as that of the main irradiation plan, and the target irradiation position coordinates (Pi).

Claims

1. A particle beam therapy system that irradiates a charged particle beam, accelerated by an accelerator and scanned by a scanning electromagnet, onto an irradiation subject, the particle beam therapy system comprising:

an irradiation management apparatus that controls the scanning electromagnet, based on target irradiation position coordinates of the charged particle beam; and

a position monitor that measures measurement position coordinates of the charged particle beam, wherein the irradiation management apparatus has a command value creator that outputs a control input to the scanning electromagnet, based on the target irradiation position coordinates and correction data created on the basis of the measurement position coordinates, measured by the position monitor in preliminary irradiation in which the excitation pattern of the scanning electromagnet is the same as that of a main irradiation plan, and the target irradiation position coordinates.

2. The particle beam therapy system according to claim 1, wherein, the irradiation management apparatus has a correction data creator that creates the correction data, based on the measurement position coordinates and the target irradiation position coordinates and a scanning electromagnet command value creator that creates a basic control input from the measurement position coordinates;

and the command value creator outputs, as the control input, a corrected control input obtained by correcting the basic control input, created by the scanning electromagnet command value creator, with the correction data created by the correction data creator.

3. The particle beam therapy system according to claim 1, wherein the correction data is created based on a value obtained by dividing by a coefficient K the difference Δ

BL between the value BL(me) of a BL product of the scanning electromagnet calculated from the measurement position coordinates measured in the preliminary irradiation and the value BL(ex) of a BL product of the scanning electromagnet calculated from the target irradiation position coordinates; and

the coefficient K is a gradient of a tangential line at a point, at which the value of the BL product is BL(ex), on the center line of the hysteresis loop configured with the BL product and the current of the scanning electromagnet.

4. The particle beam therapy system according to claim 1, wherein the irradiation management apparatus has a determination device that determines whether or not the position difference between the measurement position coordinates and the target irradiation position coordinates falls within a predetermined tolerance range;

in the case where the position difference does not fall within the predetermined range, the irradiation management apparatus creates the correction data; and

in the case where the position difference falls within the predetermined range, the irradiation management apparatus sets the control input to the scanning electromagnet to a value the same as a value in the preliminary irradiation.

5. The particle beam therapy system according to claim 2, wherein the correction data is created based on a value obtained by dividing by a coefficient K the difference Δ

BL between the value BL(me) of a BL product of the scanning electromagnet calculated from the measurement position coordinates measured in the preliminary irradiation and the value BL(ex) of a BL product of the scanning electromagnet calculated from the target irradiation position coordinates; and

the coefficient K is a gradient of a tangential line at a point, at which the value of the BL product is BL(ex), on the center line of the hysteresis loop configured with the BL product and the current of the scanning electromagnet.

6. The particle beam therapy system according to claim 2, wherein the irradiation management apparatus has a determination device that determines whether or not the position difference between the measurement position coordinates and the target irradiation position coordinates falls within a predetermined tolerance range;

in the case where the position difference does not fall within the predetermined range, the irradiation management apparatus creates the correction data; and

in the case where the position difference falls within the predetermined range, the irradiation management apparatus sets the control input to the scanning electromagnet to a value the same as a value in the preliminary irradiation.

7. The particle beam therapy system according to claim 3, wherein the irradiation management apparatus has a determination device that determines whether or not the position difference between the measurement position coordinates and the target irradiation position coordinates falls within a predetermined tolerance range;

in the case where the position difference does not fall within the predetermined range, the irradiation management apparatus creates the correction data; and

in the case where the position difference falls within the predetermined range, the irradiation management apparatus sets the control input to the scanning electromagnet to a value the same as a value in the preliminary irradiation.

8. The particle beam therapy system according to claim 5, wherein the irradiation management apparatus has a determination device that determines whether or not the position difference between the measurement position coordinates and the target irradiation position coordinates falls within a predetermined tolerance range;

in the case where the position difference does not fall within the predetermined range, the irradiation management apparatus creates the correction data; and

in the case where the position difference falls within the predetermined range, the irradiation management apparatus sets the control input to the scanning electromagnet to a value the same as a value in the preliminary irradiation.