Presentation Information
[AP1-02-INV]Development of a Compact Heavy-Ion Radiotherapy System
*Shigeki Takayama1 (1. Toshiba Energy Systems & Solutions Corporation (Japan))
Keywords:
Heavy-Ion Radiotherapy,Particle Therapy,Rotating Gantry,Synchrotron
Heavy-ion radiotherapy treats cancer by irradiating energetic carbon beams, which have a high curative effect. It also has an attractive physical characteristic called the “Bragg Peak,” enabling a high dose to be administered to deep-seated tumors while limiting the dose to the surface of the patient's body. This treatment is becoming more widespread, and many patients have benefited from it. However, this therapy system requires large equipment such as synchrotrons for accelerating ions and rotating gantries for irradiating patients with heavy ions from all directions. Since it is not feasible to install such large equipment in general hospitals, miniaturizing this equipment was necessary to provide this radiotherapy to more patients. Therefore, we have been working on miniaturizing this equipment using superconducting technology.To reduce the size of gantries, the first superconducting gantry was developed and installed in collaboration with the National Institutes for Quantum and Radiological Science and Technology (QST). It is an iso-centric gantry with an axial length of 13 m and a radius of 5.5 m. The development of this gantry was successfully completed, and it is used for treatment today. Based on the results of this development, a next-generation compact superconducting rotating gantry was developed in the project of East Japan Heavy Ion Center, Faculty of Medicine, Yamagata University. To achieve further downsizing, the length of the scanning irradiation system was shortened, and the magnetic field of the superconducting magnet was increased up to 3.5 T. As a result, the gantry was downsized to 2/3 of the first superconducting gantry. This gantry has already been installed and is working for clinical irradiation at Yamagata University. The same type of rotating gantry is planned to be installed at the Yonsei University Health System, Seoul National University Hospital, Cleveland Clinic Abu Dhabi, and Asan Medical Center too. Superconducting rotating gantries are becoming more widespread worldwide due to their compact size.To reduce the size of synchrotrons, a project called “Quantum Scalpel” was started at QST. One of the aims of this project is to develop a compact superconducting synchrotron. This synchrotron can accelerate heavy ions to a maximum energy of 430 MeV/u in 5 seconds. The circumference of the synchrotron ring is about 29 m, roughly half the circumference of the conventional ones. The superconducting magnet is composed of a pair of 45-degree combined-function superconducting coils, providing both dipole and quadrupole fields. The maximum dipole field and quadrupole field were designed to 3.5 T and 1.5 T/m, respectively. The magnet operates at a high speed of 0.64 T/s. Although such high-speed excitation generates large AC losses, a conduction cooling method using a 4K GM cryocooler was adopted for easy operation. Design studies and prototyping tests on this superconducting magnet have been carried out, and the manufacturing of the superconducting synchrotron has already started.This presentation will report on the recent progress in developing the superconducting rotating gantry and synchrotron.