Room: ePoster Forums
Purpose: Monte Carlo simulation of Proton, Helium, and Carbon beams are performed to generate data for the commissioning of a treatment planning system (matRad), to investigate ion type specific properties, i.e., secondary particle production, target fragmentation and penumbrae sizes. These properties determinine the viability of the modalities for pediatric treatments. Using models to predict toxicities (secondary cancers, probabilities of adverse immunological response, and other acute and late effects), benefits and drawbacks will be determined.
Methods: Monte Carlo simulations provide the matRad commissioning data, which will be commissioned for three ion species. Pediatric treatment plans, developed at the Proton Therapy Center in Houston, will be used to create treatment plans for all investigated ions, taking estimates of RBE for each species into account. The plans will be calculated in matRad and simulated using our in-house MC systems, FDC and MC2. Results of these simulations provide physical dose distributions, LET distributions, as well as out of field doses from secondary particles, i.e., ions and neutrons. Using these data, we will estimate NTCPs and possible incidence rates of late toxicities.
Results: A detailed He-ion machine for matRad has been created and the performance is currently being validated against Monte Carlo simulations. Generic proton and carbon machine configurations are available in the published matRad distribution, but will be updated as more detailed Monte Carlo simulation results become available. Initial comparison of Monte Carlo simulations out of proton, helium, and carbon beams indicate, that helium may provide advantages in terms of higher dose conformality than protons, due to a smaller penumbra size, and also shows advantages compared to carbon fields, i.e., a reduced dose distal to the nominal particle range from low target fractionation rates and recoil ions.
Conclusion: A study to determine the optimum ion for pediatric ion therapy is ongoing.