Performance of multiple-energy operation for scanned carbon-ion therapy at HIMAC

Purpose: For conducting the treatments by scanning irradiation without the use of the energy absorbers, the accelerator system is required to output therapy beams of many different energies. In addition, it is also demanded that the properties, such as spill, position and size, of the beams are reliable for irradiation accuracy.Methods: We have developed a multiple-energy operation method to produce the carbon-ion beams with various energies of more than 200 steps between 56 and 430 MeV/u in a single cycle of the synchrotron. By using this method, the accelerator system can perform a quick change of the output beam energy. To verify that the output beams would meet therapy requirements, we carried out the irradiation experiments at Heavy Ion Medical Accelerator in Chiba (HIMAC).Results: The beam intensity was controlled as required from the irradiation control system, and the beam spill ripple was low in the wide intensity range between 107 and 109 particles per second (pps). The position and size of the beam spot were stable, and their fluctuations were small for all beam energies.Conclusions: The experimental results proved that our system can provide the beams meeting the therapy requirements for all available energies. We will report the performance of our system in our presentation.53rd Annual Conference of the Particle Therapy Co-Operative Group (PTCOG53