@misc{oai:repo.qst.go.jp:00071661,
 author = {Mizushima, Kota and 水島 康太},
 month = {May},
 note = {Abstract
In scanned carbon-ion therapy, the narrow beam is desired to reduce damage to healthy tissue around the tumor. Since the energy absorbers increase the beam size by the multiple scattering, the accelerator system must output therapy beams with various energies to perform irradiation without using them. In addition, it is also required that the beam-intensity control is reliable for all energies to ensure irradiation accuracy. 
At the Heavy Ion Medical Accelerator in Chiba (HIMAC), multiple-energy operation has been developed to produce the carbon-ion beams with different energies of more than 200 steps between 48 and 430 MeV/u in a single cycle of the synchrotron. To put this operation to practical use, we have upgraded the beam-intensity control system at the HIMAC synchrotron and have introduced the fast beam chopper system in the high energy beam transport (HEBT). To verify the performance of our system, we carried out the irradiation experiments. 
The accelerator system could change the output beam energy quickly. The beam intensity could be controlled as required from the irradiation control system. The ripple of the beam spill was low in the wide intensity range. The HEBT chopper system prevented the uncontrollable spilled beam, induced by the emittance growth during beam deceleration, delivering to the irradiation port. 
We confirmed that the accelerator system can provide the beams meeting the therapy requirements for all available energies. We will report the experimental results of our system in our presentation., 54th Annual Conference of the Particle Therapy Co-Operative Group (PTCOG54)},
 title = {Upgrade of the beam extraction control system for scanned carbon-ion therapy at HIMAC},
 year = {2015}
}