A compact proton accelerator system for cancer therapy

摘要

The basic design of a compact proton accelerator system for cancer therapy is described. The system consists of a 30 keV ion source, a 3 MeV RFQ linac, and a rapid-cycling 235 MeV synchrotron. A strong focusing combined function magnet, which has both focusing and defocusing section in a unit, is adopted instead of a quadrupole magnet. The RF system applies a compact ferrite loaded tuning-free cavity which has no bias windings. The synchrotron is operated at 20 Hz repetition with fast beam extraction. It is the same method as the KEK booster synchrotron, which has been using for proton therapy studies by Tsukuba University. In this system, a breath synchronized irradiation method is easily realized and the energy of proton beam can be changed flexibly within few minutes.