2020 年 17 巻 2 号 p. 62-69
Recently, the demand for proton beam therapy is increasing because of less radiation exposure to healthy tissues. In order to reduce footprint of proton therapy systems, we developed a compact proton synchrotron with a circumference of 18 m. The number of electromagnets that make up the compact synchrotron is reduced to 11 by applying horizontally weak focusing optics. Stable operation of the synchrotron was realized by cooperation of three-dimensional magnetic field analysis and particle tracking simulation. The synchrotron has been applied for proton beam therapy with scanning irradiation method since 2014. Since the compact synchrotron is introduced to more than 10 facilities in the world, including under construction. We started development of new accelerator for further downsizing. This synchrotron and new accelerator are expected to greatly contribute spreading of proton therapy systems.