Particle therapy system

1. A particle therapy system, comprising:

a synchrotron which generates a charged particle beam;

a beam delivery system which irradiates an irradiation target with a charged particle beam extracted from the synchrotron thereby forming a radiation field;

a rotating gantry which is provided with the beam delivery system and is rotatable around the irradiation target; and

a dispersion measuring device which measures the dispersion of the charged particle beam at the position of the irradiation target at a plurality of rotation angles of the rotating gantry,

wherein the orbit center of the charged particle beam extracted from the synchrotron and the rotation axis of the rotating gantry are located on substantially the same straight line, and

wherein the charged particle beam has vertical and horizontal dispersions at the plurality of rotation angles of the rotating gantry, and the vertical and horizontal dispersions are simultaneously corrected to zero.

2. The particle therapy system according to claim 1 , wherein

a high energy beam transport system which linearly transports the charged particle beam from the synchrotron to the rotating gantry is provided on a line extending from the rotation axis of the rotating gantry.

3. The particle therapy system according to claim 1 , wherein

the dispersion at the position of the irradiation target is adjusted using a quadrupole magnetic field generator.

4. The particle therapy system according to claim 3 , wherein

the dispersion at the position of the irradiation target is adjusted within such a range that the amount of change in the position of the beam at the position of the irradiation target when the momentum of the beam changes by 0.01% becomes 0.5 mm or less.

5. The particle therapy system according to claim 1 , further comprising:

a deflector for extraction disposed at an exit of the synchrotron to receive the charged particle beam, the deflector for extraction including a first quadrupole magnet,

wherein the defector for extraction is disposed between the exit of the synchrotron and an entry of the beam delivery system,

wherein the beam delivery system includes a second quadrupole magnet, and

wherein excitation amounts of the first and second quadrupole magnets are adjusted to correct the horizontal and vertical dispersions at the plurality of gantry rotations of the rotating gantry simultaneously to zero.

6. A particle therapy system, comprising:

a synchrotron which generates a charged particle beam;

a beam delivery system which irradiates an irradiation target with a charged particle beam extracted from the synchrotron thereby forming a radiation field;

a rotating gantry which is provided with the beam delivery system and is rotatable around the irradiation target; and

a dispersion measuring device which measures the dispersion of the charged particle beam at the position of the irradiation target at a plurality of rotation angles of the rotating gantry,

wherein the plurality of rotation angles of the rotating gantry include at least 0° and 90°, and

wherein the orbit center of the charged particle beam extracted from the synchrotron and the rotation axis of the rotating gantry are located on substantially the same straight line.

7. The particle therapy system according to claim 6 ,

wherein the charged particle beam has vertical and horizontal dispersions at the plurality of rotation angles of the rotating gantry, and the vertical and horizontal dispersions are simultaneously corrected to zero.

8. The particle therapy system according to claim 7 , further comprising:

a deflector for extraction disposed at an exit of the synchrotron to receive the charged particle beam, the deflector for extraction including a first quadrupole magnet,

wherein the defector for extraction is disposed between the exit of the synchrotron and an entry of the beam delivery system,

wherein the beam delivery system includes a second quadrupole magnet, and

wherein excitation amounts of the first and second quadrupole magnets are adjusted to correct the horizontal and vertical dispersions at the plurality of gantry rotations of the rotating gantry simultaneously to zero.

9. The particle therapy system according to claim 6 , further comprising:

a deflector for extraction disposed at an exit of the synchrotron to receive the charged particle beam, the deflector for extraction including a first quadrupole magnet,

wherein the defector for extraction is disposed between the exit of the synchrotron and an entry of the beam delivery system,

wherein the beam delivery system includes a second quadrupole magnet, and

wherein excitation amounts of the first and second quadrupole magnets are adjustable to change the horizontal and vertical dispersions at the plurality of gantry rotations of the rotating gantry.

10. The particle therapy system according to claim 6 , further comprising:

a high energy beam transport system, which linearly transports the charged particle beam from the synchrotron to the rotating gantry, on a line extending from the rotation axis of the rotating gantry.

11. The particle therapy system according to claim 6 ,

wherein the dispersion at the position of the irradiation target is adjusted using a quadrupole magnetic field generator.

12. The particle therapy system according to claim 11 ,

wherein the dispersion at the position of the irradiation target is adjusted within such a range that the amount of change in the position of the beam at the position of the irradiation target when the momentum of the beam changes by 0.01% becomes 0.5 mm or less.