RESUMEN
PURPOSE: We investigate the possibility to improve the accuracy of the lateral dose profile for 4He beams with a novel approach, by extending an already validated model for proton beams to heavier ions. METHODS: The full Molière theory for the Coulomb multiple scattering is applied to the case of 4He beams, with a complete separation of the electromagnetic and of the nuclear contributions in the calculation of the total dose. The latter is described with only three free parameters. RESULTS: The accuracy of the results compared with Monte Carlo predictions already validated with experimental data is comparable with other studies at low energy, but improves by a factor 2 at high energy. In addition the found solution is more stable with respect to (multi-) Gaussian and other parameterizations. This result makes this method of interest for applications to Treatment Planning Systems (TPS) in ion beam therapy. CONCLUSIONS: We propose a model, named MONETα (MOdel of ioN dosE for Therapy for α), for the calculation of the lateral dose of 4He beams in water that allows fast and accurate dose calculations by requiring a small data base of parameters as input.