Search

Abstract: Multiple-energy synchrotron operation providing carbon-ion beams with various energies has been used for scanned particle therapy at NIRS. An energy range from 430 to 56MeV/u and about 200 steps within this range are required to vary the Bragg peak position for effective treatment. The treatment also demands the slow extraction of beam with highly reliable properties, such as spill, position and size, for all energies. We propose an approach to generating multiple-energy operation meeting these requirements within a short time. In this approach, the device settings at most energy steps are determined without manual adjustments by using systematic parameter tuning depending on the beam energy. Experimental verification was carried out at the HIMAC synchrotron, and its results proved that this approach can greatly reduce the adjustment period. [Copyright &y& Elsevier]

Abstract: For the quality assurance (QA) of therapeutic scanned carbon-ion beams, QA tool having high spatial resolution is required. The radiochromic film (such as Gafchromic EBT2 film model) is a very useful tool because of its high spatial resolution, self-development, and near tissue equivalence. However, for a complex field in carbon-ion therapy, it is difficult to unambiguously determine the dose from the measured net optical density (OD). As a first approach, we investigated the response of EBT2 to carbon-ion beam at the Heavy Ion Medical Accelerator in Chiba (HIMAC) in Japan. Based on the measured results, we performed QA measurements independently of dose. We verified the QA measurements by EBT2 by comparing the ionization chamber and the fluorescent screen. The results obtained with EBT2 were in good agreement with those obtained with the other detector. In addition, to test the use in a complex field, we verified the OD distributions for moving and static target by means of a gamma index analysis. As a result, we confirmed that EBT2 could be used as a part of QA procedures for therapeutic scanned carbon-ion beams. [Copyright &y& Elsevier]

A superconducting rotating-gantry for carbon-ion radiotherapy was developed. This isocentric rotating gantry can transport carbon ions having the maximum kinetic energy of E = 430 MeV/ u to an isocenter with irradiation angles of over ±180°, and is further capable of performing three-dimensional raster-scanning irradiation. By using combined-function superconducting magnets, we could design a compact rotating gantry for carbon-ion radiotherapy. Construction of the gantry structure began since early 2014, and the installation of the entire gantry system to the Heavy Ion Medical Accelerator in Chiba (HIMAC) complex was completed by the end of September, 2015. Beam tuning subsequently began since October, 2015, and carbon ions, as accelerated by the HIMAC upper synchrotron, having kinetic energies of between E = 430–48 MeV/ u were successfully transported with the rotating gantry to the isocenter. The size and shape of the beam spots at the isocenter is being tuned over various combinations of the beam energies and the gantry angle. We will present the recent progress as well as the current status of the superconducting rotating-gantry. [ABSTRACT FROM AUTHOR]

Abstract: The NIRS has carried out carbon-ion radiotherapy (RT) with HIMAC since 1994. On the basis of their ten-year HIMAC experience, NIRS has developed a standard-type CIRT facility in order to boost availability of carbon-ion RT in Japan. Work has been carried out at its pilot facility at Gunma University since 2010. The current projects of the pilot facility include Saga-HIMAT and i-ROCK, promoted by the Kanagawa prefectural cancer center. Toward the further sophisticated conformal carbon-ion RT with HIMAC, the NIRS has since 2006 been developing new treatment technologies, such as a fast 3D rescanning with a pencil beam and a compact rotating gantry. [Copyright &y& Elsevier]

Abstract: A flat radiation field for heavy ion beams is used in research experiments and clinical treatments. When a flat field is required, a beam spreading system must be installed for a beam line; thus a simple and affordable method is desirable. To achieve the carbon ion beam spreading, we employed a dual-ring double scattering method (DDSM), which consists of an initial scattering foil and a dual-ring subsequent scatterer. The scatterers for the DDSM were designed and tested to verify the flatness of the radiation field of the carbon ion beam. We obtained 100mm of the flat radiation field in the isocenter plane for the 2D radiation field, as expected. For the 3D radiation field, we obtained a field size of 80mm. With a 60-min setup time, using the DDSM system, and by placing only two scatterers, we can form the flat radiation field. [Copyright &y& Elsevier]