Patent ID: 9078335
Filing Date: 2015-07-07
Classification: A61N,H05H

Abstract:
1. A charged particle beam transport system that transports a charged particle beam to a particle beam irradiation apparatus mounted in a rotating gantry capable of rotating around an isocenter, the charged particle beam transport system comprising: a rotating deflection unit that is mounted in the rotating gantry and rotates around a gantry rotation axle of the rotating gantry; and a fixed transport unit ranging from an accelerator to the rotating deflection unit, wherein letting an x direction denote a direction on a circular orbit plane of the accelerator in a plane perpendicular to a traveling direction of the charged particle beam at a launching position of the accelerator and letting a y direction denote a direction perpendicular to the x direction in a plane perpendicular to the traveling direction of the charged particle beam, the charged particle beam launched from the accelerator is a charged particle beam whose x-direction and y-direction emittances are different from each other, wherein the rotating deflection unit includes two or more deflection electromagnets, the fixed transport unit includes two or more quadrupole electromagnets, wherein when viewed from the gantry rotation axle, a gantry angle is defined as an angle between a beam center line of the particle beam irradiation apparatus and y-direction axis of the charged particle beam at an inlet of the rotating deflection unit, wherein a gantry reference angle is defined as an angle of the rotating gantry at which the charged particle beam is transported in such a way that x-direction and y-direction emittances at the launching position of the accelerator are separated and the respective emittances are maintained, wherein a first phase advance is defined as a change in a phase, of a phase space distribution of the charged particle beam, that advances when the charged particle beam travels from the inlet of the rotating deflection unit to the isocenter in the case where the gantry angle is the gantry reference angle, wherein a second phase advance is defined as a change in a phase, of the phase space distribution of the charged particle beam, that advances when the charged particle beam travels from the inlet of the rotating deflection unit to the isocenter in the case where the gantry angle is turned by 90° from the gantry reference angle, and wherein the fixed transport unit controls excitation amounts of the quadrupole electromagnets in such a way that a phase of the phase space distribution of the charged particle beam at the inlet of the rotating deflection unit coincides with a phase determined by a calculation based on an average value of the first phase advance and the second phase advance.