SU-E-T-282: Preliminary Simulation Study for 3 Dimensional Dose Delivery in Carbon Beam Active Scanning System of...

KHIMA (Korea Heavy Ion Medical Accelerator) project has a plan to develop and construct a research beam line for carbon beam active scanning system. The carbon beam line consists with scanning magnet, beam-monitoring system, energy modulation system. In this study, the significant components, scanning magnets and ridge filter, were designed for the carbon beam active scanning beam line.

The designed scanning magnet and ridge filter were used for 3 dimensional active beam dose delivery simulation by Geant4 Monte Carlo code. The target volume of the active scanning was 10 × 10 × 5 cm² on the water phantom with 400 MeV/u of carbon beam. The transvers plane on the target was scanned by 3mm of step size. And, the optimized weighting factors of transverse scanning were obtained by MINUIT fitting package of ROOT. An aluminum ridge filter was designed to generate 5 cm of physical SOBP through step shape, which was optimized through in-house iteration method and the MINUIT package.The simulation was performed with Geant4 through applying the transverse scanning with the obtained weighting factor and the designed ridge filter.

The uniformity on the transverse plan will be expected below 4% when it considered scattered beam. Also, the uniformity for longitudinal plane will be expected lower then 5%.

This preliminary computational study was shown a possibility of using ridge filter for acceptable 3 dimensional uniformity on active beam delivery system in carbon beam therapy line. The optimization process to reach an acceptable uniformity on clinical use should be followed. In addition, it would be used for the design of treatment planning system software for KIHMA project.