Patent ID: 9630027
Date: 2017-04-25
CPC Classifications: A61N,H05H

Claim:
1. A beam transport system for transporting a charged particle beam emitted from an accelerator to an irradiation position, comprising: at least one bending electromagnet that deflects the charged particle beam; at least two quadrupole electromagnets that focus or defocus the charged particle beam; at least one beam profile monitor that detects profile data of the charged particle beam; a beam analyzer that calculates based on the profile data, a beam temporal-variation related amount that is a beam-position temporal variation amount or a beam diameter, at the beam profile monitor; an optical parameter calculator that calculates optical parameters of the beam transport system; and an electromagnet power source that sets an excitation current of each of the bending electromagnet and the quadrupole electromagnets, based on the optical parameters calculated by the optical parameter calculator; wherein the optical parameter calculator: calculates based on the beam temporal-variation related amount, a start-point momentum dispersion function that is a momentum dispersion function of the charged particle beam at a start point in design of the beam transport system that is set on a beam trajectory of the accelerator; and calculates said optical parameters using, as an initial condition, the start-point momentum dispersion function and a beginning condition at the irradiation position at the time of detecting the profile data.