Charged-particle beam irradiation method and system

• US 6,265,837 B1
• Filed: 03/09/1999
• Issued: 07/24/2001
• Est. Priority Date: 03/10/1998
• Status: Expired due to Fees

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Akiyama, Hiroshi, Matsuda, Koji, Hiramoto, Kazuo
• Primary Examiner(s): Berman, Jack
• Assistant Examiner(s): Wells, Nikita
• Application Number:
  US09/265,557
• Time in Patent Office: 868 Days
• Field of Search: 315/503, 315/501, 313/359.1, 250/505.1, 250/492.3
• US Class Current: 315/503
• CPC Class Codes: A61N 2005/1087 Ions; Protons
• CPC Class Codes: A61N 2005/1095 Elements inserted into the radiation path within the system, e.g. filters or wedges
• CPC Class Codes: A61N 5/1043 Scanning the radiation beam, e.g. spot scanning or raster scanning
• CPC Class Codes: A61N 5/1045 using a multi-leaf collimator, e.g. for intensity modulated radiation therapy or IMRT
• CPC Class Codes: G21K 5/04 with beam-forming means

Abstract

A charged-particle beam irradiation method and system are disclosed in which while a charged-particle beam ejected from an accelerator is scanned by an electromagnet, each layer resulting from the division of an affected part into a plurality of layers in the direction of progression of the charged-particle beam is irradiated with the charged-particle beam. The intensity of a charged-particle beam for irradiation of a first layer is made lower than the intensity of a charged-particle beam for irradiation of a second layer existing at a position deeper than the first layer in the beam progressing direction. A scanning speed in the first layer is changed between a portion of the first layer subjected to irradiation at the time of irradiation of the second layer and a portion of the first layer subjected to no irradiation at the time of irradiation of the second layer.

Claims

1. A charged-particle beam irradiation method in which while a charged-particle beam ejected from an accelerator is scanned by an electromagnet, each layer resulting from the division of an affected part into a plurality of layers in the direction of progression of said charged-particle beam is irradiated with the charged-particle beam,

wherein the intensity of a charged-particle beam for irradiation of a first layer is made lower than the intensity of a charged-particle beam for irradiation of a second layer existing at a position deeper than said first layer in the beam progressing direction, and a scanning speed in said first layer is changed between a portion of said first layer subjected to irradiation at the time of irradiation of said second layer and a portion of said first layer subjected to no irradiation at the time of irradiation of said second layer.

3. A charged-particle beam irradiation method according to claim 1 or 2, wherein said accelerator includes a synchrotron for ejecting a charged-particle beam through the application of a high-frequency electric field thereto, and the intensity of said charged-particle beam is controlled by controlling said high-frequency electric field.

4. A charged-particle beam irradiation method according to claim 3, wherein said high-frequency electric field is generated from an electrode applied with a high-frequency electric power, and said high-frequency electric field is controlled by controlling the power value of said high-frequency electric power.

5. A charged-particle beam irradiation method according to claim 1 or 2, wherein the intensity of said charged-particle beam is controlled by controlling the amount of ions injected into said accelerator.

6. A charged-particle beam irradiation method according to claim 1 or 2, wherein the scanning of said charged-particle beam is performed on the basis of the dose value of said charged-particle beam.

7. A charged-particle beam irradiation method according to claim 1 or 2, wherein a layer to be irradiated with said charged-particle beam is changed by changing the energy of said charged-particle beam, and said change in energy is made by a degrader disposed on an orbit of said charged-particle beam.

2. A charged-particle beam irradiation method in which while a charged-particle beam ejected from an accelerator is scanned by an electromagnet, each layer resulting from the division of an affected part into a plurality of layers in the direction of progression of said charged-particle beam is irradiated with the charged-particle beam,

wherein the intensity of said charged-particle beam for irradiation of each layer is made lower as the position of that layer becomes shallower in the beam progressing direction, and a scanning speed in a shallower layer is changed between a portion of said shallower layer subjected to irradiation at a flat portion of a charged-particle beam characteristic at the time of irradiation of a deeper layer and a portion of said shallower layer subjected to no irradiation at the time of irradiation of said deeper layer.

8. A charged-particle beam irradiation system in which while a charged-particle beam ejected from an accelerator is scanned by an electromagnet, each layer resulting from the division of an affected part into a plurality of layers in the direction of progression of said charged-particle beam is irradiated with the charged-particle beam, the system comprising:

intensity control means for making the intensity of a charged-particle beam for irradiation of a first layer lower than the intensity of a charged-particle beam for irradiation of a second layer existing at a position deeper than said first layer in the beam progressing direction; and

scanning speed changing means for changing a scanning speed in said first layer between a portion of said first layer subjected at the time of irradiation of said second layer and a portion of said first layer subjected to no irradiation at the time of irradiation of said second layer.

10. A charged-particle beam irradiation system according to claim 8 or 9, wherein said accelerator includes a synchrotron for ejecting a charged-particle beam through the application of a high-frequency electric field thereto, and there is provided control means for controlling said high-frequency electric field to control the intensity of said charged-particle beam.

11. A charged-particle beam irradiation system according to claim 10, wherein said high-frequency electric field is generated from an electrode applied with a high-frequency electric power, and there is provided control means for controlling the power value of said high-frequency electric power to control said high-frequency electric field.

12. A charged-particle beam irradiation system according to claim 8 or 9, wherein there is provided control means for controlling the amount of ions injected into said accelerator to control the intensity of said charged-particle beam.

13. A charged-particle beam irradiation system according to claim 8 or 9, wherein there is provided control means for performing the scanning of said charged-particle beam on the basis of the dose value of said charged-particle beam.

14. A charged-particle beam irradiation system according to claim 8 or 9, wherein a layer to be irradiated with said charged-particle beam is changed by changing the energy of said charged-particle beam, and there is provided a degrader disposed on an orbit of said charged-particle beam for making said change in energy.

9. A charged-particle beam irradiation system in which while a charged-particle beam ejected from an accelerator is scanned by an electromagnet, each layer resulting from the division of an affected part into a plurality of layers in the direction of progression of said charged-particle beam is irradiated with the charged-particle beam, the system comprising:

intensity control means for making the intensity of said charged-particle beam for irradiation of each layer lower as the position of that layer becomes shallower in the beam progressing direction; and

scanning speed changing means for changing a scanning speed in a shallower layer between a portion of said shallower layer subjected to irradiation at a flat portion of a charged-particle beam characteristic at the time of irradiation of a deeper layer and a portion of said shallower layer subjected to no irradiation at the time of irradiation of said deeper layer.