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.

RIKEN Heavy-Ion Linac (RILAC) of Radioactive Isotope Beam Factory (RIBF) is undergoing an upgrade of its acceleration voltage to allow it to further investigate new super-heavy elements. In this project, a new superconducting (SC) booster linac has been developed and constructed. The SC-Linac consists of 10 TEM quarter-wavelength resonators (QWRs) made from pure niobium sheets which operate at 4 K. Recently we succeeded to develop high performance SC-cavities which satisfies the requirement as Q₀ of 1×10⁹ with its accelerating gradient of 6.8 MV/m with a wide margin. The QWRs were integrated to three cryomodules and installed to the beam line. This paper describes about design, fabrication, processing and testing of newly developed superconducting cavity and commissioning status after installation.

The Institute for Integrated Radiation and Nuclear Science, Kyoto University has been working with Sumitomo Heavy Industries, Ltd. to develop a boron neutron capture therapy (BNCT) system using a cyclotron since 2007. After a joint non-clinical trial of boron drug with STELLA PHARMA CORPORATION, as a clinical trial of Sumitomo Heavy Industries, Ltd. and STELLA PHARMA CORPORATION, the world’s first accelerator-based BNCT phase I clinical trial for recurrent malignant glioma was started in 2012. Phase I clinical trial for head and neck cancer was also started in 2014. In 2016, we started a phase II clinical trial for recurrent malignant glioma jointly with the Southern TOHOKU BNCT Research Center. From the same year, a phase II clinical trial for head and neck cancer was started at the Southern TOHOKU BNCT Research Center. Based on this result, Sumitomo Heavy Industries, Ltd. obtained medical device approval for manufacturing and sales of accelerator based BNCT system NeuCure™ on March 11, 2020 for the treatment of locally unresectable recurrent or unresectable advanced head and neck cancer. STELLA PHARMA CORPORATION received approval on March 25, 2020, to manufacture and sell Steboronin^®. This paper presents an outline and current status of a boron neutron capture therapy system using a cyclotron.

It has been almost 50 years since Research Center for Nuclear Physics (RCNP) was established in Osaka University. In this article, the brief history of RCNP is summarized from the beginning of the study for nuclear physics using the cyclotron accelerators at the faculty of science in Osaka University up to the foundation of RCNP and then the construction of the ring cyclotron.

I first started my overseas life in France after my Ph.D. I planned to spend two years there, but I got the chance to work in Germany afterward. Now nine years have already passed since leaving Japan. I have learned the difference in work style and work–life balance between Japan and Europe. On top of that, the experience always brought me new valuable ideas. In this article, I will report on my overseas life and working experience in France and Germany.