In order to provide a uniform and desirable dose distribution over a large radiation field, spot beam scanning is one of the most useful methods. A new spot beam scanning system was constructed for a 70 MeV proton beam. The lateral dose distribution was uniform with +/- 2.5% for an 18 cm square field. It was possible to control the dose at each point in the radiation field by this spot scanning method. This system has been confirmed to be satisfactory for delivering a proton beam in the desired field shape and dose level.

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Ion sources for medical facilities should have characteristics of easy maintenance, low electric power consumption, good stability, and long operation time without problems (one year or longer). For this, a 10GHz compact electron-cyclotron-resonance ion source with all-permanent magnets (Kei2 source) was developed. The maximum mirror magnetic fields on the beam axis are 0.59T at the extraction side and 0.87T at the gas-injection side, while the minimum B strength is 0.25T. These parameters have been optimized for the production of C4+ based on the experience at the 10GHz NIRS-ECR ion source and a previous prototype compact source (Kei source). The Kei2 source has a diameter of 320mm and a length of 295mm. The beam intensity of C4+ was obtained to be 530μA under an extraction voltage of 40kV. The beam stability was better than 6% at C4+ of 280μA during 90h with no adjustment of the operation parameters. The details of the design and beam tests of the source are described in this paper.

The usefulness of particle beams for radiation therapy has been well and widely recognized. For the cure of cancer patients, many accelerator facilities have already been utilized, and some new facilities are now being put into operation, or are under construction. Considering the medical and biological requirements, light heavy ions with an energy of several hundred MeV/nucleon are regarded as being the most suitable species. A reasonable choice to this end is an accelerator complex, for an example, one comprising an ion source, an injector linac, and a synchrotron. The ion source is of great importance, since its characteristics strongly affect the overall performance of the accelerator system. A pulsed Penning source (PIGIS) has been successfully used at Lawrence Berkeley Laboratory. Recently, at the National Institute of Radiological Sciences a low-duty pulsed PIGIS for the heavy-ion medical accelerator in Chiba (HIMAC) has been developed; it has both a long lifetime and a high peak intensity. As other types of ion sources, an electron-beam ion source (EBIS) and an electron-cyclotron-resonance ion source (ECRIS) are being developed at several laboratories. An EBIS is basically a pulsed source, and is being successfully used at Saclay. By using an after-glow mode, two ECRISs have made remarkable progress at Grenoble and the Grand Accelerateur National d’Ions Lourds; similar tests are proceeding for the Schwer-Ionen Synchrotron at the Gesellschaft für Schwer-Ionenforschung, the booster at Centre d’Europeen de Recherche Nucleaire, and the HIMAC. These different types of heavy-ion sources are discussed from the viewpoint of their application to radiation therapy.