Contents I. Introduction
The rotating gantry is cylindrical irradiation equipment with magnets for beam transport and beam scanning (Fig. 1). It can deliver particle beams precisely to a tumor from any direction without changing the posture of the patient, thus making it possible to concentrate the physical dose to the tumor while reducing the dose to normal cells. Therefore, it has been commonly used in proton radiotherapy in recent years. However, for carbon-ion radiotherapy, the rotating gantry was too big to be installed at general hospitals because of the high magnetic rigidity of therapeutic carbon ions. To reduce the size of the gantry, a next-generation compact superconducting rotating gantry had been developed in a project of the East Japan Heavy Ion Center, Faculty of Medicine, Yamagata University. To achieve further downsizing of the rotating gantry, the length of the scanning irradiation system is reduced by arranging a horizontal and a vertical scanning magnet, which were wound with normal conductors, in parallel [1]. Furthermore, the magnetic field of the superconducting magnet is increased up to 3.5 T from 2.88 T of the first superconducting gantry installed in the National Institutes for Quantum and Radiological Science and Technology (QST) [2]. This increase of magnetic field is achieved primarily by increasing the magnetomotive force. As a result, the gantry is downsized to 2/3 of the first superconducting gantry. This gantry has already been installed and is undergoing preclinical commissioning at Yamagata University. A rotating gantry of the same type is to be installed for the Yonsei University Health System and Seoul National University Hospital, too. This paper reports on this gantry and its superconducting magnet.
Three-dimensional image of the next-generation compact superconducting rotating gantry for heavy-ion radiotherapy.
