STUDY ON THE REALIZATION OF A COMPACT PROTON ACCELERATOR FOR CANCER THERAPY

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Radiation cancer therapy is noteworthy from the point of view of quality of life of the patients because of the merit of keeping the function of the body. Especially proton therapy has become important because it is equivalent to the X ray in the biological effect and tremendous amount of experience of treatment with X ray can be effectively utilized in addition to the fact that it can localize the radiation dose to the affected part. In the present study, we have developed a compact proton accelerator for cancer therapy in order to enable wide spread use of proton therapy.In detail, the following studies have been advanced priented for proton synchrotron which can be easily operated with various energies.1.Combined-function lattice is adopted for the merit of compactness and eazy operation. As the slow beam extraction method, we have adopted the new scheme to apply a transverse RF electric field keeping the betatron tune to be constant, which is suitable for the synchronization of the … More beam irradiation with breathing of the patient.2.After the reduction of the required acceleration voltage by optimization of the acceleration pattern, we have adopted an untuned RF accelerating cavity, which avoided the complicated tuning of the RF cavity. By invention of a new power feeding method called multi-feed coupling, efficiency of utilization of the applied RF power has been largely improved by the reduction of reflection power. An RF acceleration cavity applicable to a real proton synchrotron dedicated for cancer therapy has been completed with the untuned type excited by a 2kW solid state amplifier. By the high power test, it is found to be well put to practical use from the points of view of generated gap-voltage, necessary input power and its temperature rise.3.An RF control device fabricated on the boards of the personal computer has been developed adopting a digital synthesizer with good purity of frequency. With use of this devive, feed back control with beam position and phase error is considered to become unnecessary if the step frequency control according to the change of the magnetic field is precise enough. Thus the daily routine operation of the synchrotron is expected to be possible. Less