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Multiple-energy synchrotron operation was developed to realize fast 3D scanning irradiation for carbon-ion radiotherapy. This type of operation can output various carbon-ion beams with different energies in a single synchrotron cycle. The beam control system used in this kind of operation was developed to quickly provide the beam energy and intensity required from the irradiation control system. The performance of the system was verified by experimental tests. The system could output beams of 197 different energies in 63 s. The beam intensity could be controlled for all the output beams without large ripples or overshooting. The experimental test of irradiation for prostate cancer treatment was also successfully performed, and the test results proved that our system can greatly reduce the irradiation time. [ABSTRACT FROM AUTHOR]

Abstract: Multiple-energy synchrotron operation providing carbon-ion beams with various energies has been used for scanned particle therapy at NIRS. An energy range from 430 to 56MeV/u and about 200 steps within this range are required to vary the Bragg peak position for effective treatment. The treatment also demands the slow extraction of beam with highly reliable properties, such as spill, position and size, for all energies. We propose an approach to generating multiple-energy operation meeting these requirements within a short time. In this approach, the device settings at most energy steps are determined without manual adjustments by using systematic parameter tuning depending on the beam energy. Experimental verification was carried out at the HIMAC synchrotron, and its results proved that this approach can greatly reduce the adjustment period. [Copyright &y& Elsevier]

The HIMAC clinical study has been conducted with a carbon-ion beam since June 1994. Since 2006, as a new treatment research project, NIRS has developed both the accelerator and beam-delivery technologies for the sophisticated heavy-ion radiotherapy, which brings a pencil-beam 3D rescanning technology for both the static and moving-tumor treatments. In this technology, the depth-scanning technique was improved to the full-energy depth scanning by realizing a variable-energy operation of the HIMAC synchrotron itself. At present, a heavy-ion rotating gantry has been developed with the superconducting technology and is in a beam-commissioning stage. As a future plan, we just start a study of a multi-ions irradiation for more sophisticated LET-painting and a design study of a superconducting synchrotron for more compact heavy-ion radiotherapy facility. [ABSTRACT FROM AUTHOR]

Controlling beam position in three-dimensional pencil-beam scanning is important because errors in beam position disturb the uniformity of irradiated dose distribution. To suppress this, we have developed a simple procedure for beamline tuning. Beamline tuning is performed with steering magnets and fluorescent screen monitors to converge a beam’s trajectory to a central orbit. The misalignment between beam position and a reference axis is determined through a verification system, which consists of a screen monitor and an acrylic phantom. If beam position deviates from the reference axis, two pairs of steering magnets, which are placed downstream of the beam transport line, correct the beam. These adjustments are iterated until the deviations for 11 energies of the beam are within 0.5 mm of the reference axis. To demonstrate the success of the proposed procedure, we used it to perform beam commissioning at the Kanagawa Cancer Center.
 [ABSTRACT FROM AUTHOR]