Development of a Superconducting Rotating-gantry for Carbon-ion Radiotherapy

Abstract

A superconducting rotating-gantry for carbon-ion radiotherapy was developed. This isocentric gantry can transport carbon ions having kinetic energies of between E=430-56 MeV/𝑢 to an isocenter over an irradiation angle of ±180 degrees, and is further capable of performing three-dimensional raster-scanning irradiation. The rotating gantry equips combined-function superconducting magnets. Since these magnets can provide both dipole and quadrupole fields, no quadrupole magnet is required for beam focusing. Having used the combined-function superconducting magnets and optimized the layout of the gantry as well as the beam optics, the length and radius of the gantry became approximately 13 m and 5.5 m, respectively, which are comparable to those for proton gantries. Construction of the entire rotating-gantry system was completed by the end of September, 2015. Having performed beam commissioning over various combinations of gantry angles and beam energies, we could successfully obtain the designed beam quality, which satisfies the requirements of scanning irradiation. Cancer treatments using the superconducting rotating-gantry were started since May, 2017.