Abstract ID: 172 Novel data relevant for helium ion therapy and their comparison with FLUKA nuclear reaction models

Abstract

4He ions are considered an attractive modality supplementary to protons and 12C ions for use in cancer radiation therapy. The accelerator and beam application system at the Heidelberg ion-beam therapy center (HIT) are currently commissioned for clinical application of 4He ions, which involves the calculation of basic data for the treatment planning system (laterally integrated depth dose profiles, lateral dose profiles and fragment distributions in water). For the commissioning of protons and 12C ions at HIT the FLUKA code [1] , [2] has been used [3] . The models for light ion interactions in FLUKA are undergoing several improvements and enhancements [4] particularly for 4He and their performances have already been investigated for calculation of 4He dosimetric data [5] . While the shape of the Bragg peak curve is mostly dominated by the Landau fluctuations in the projectile energy losses, its height is mainly determined by the nuclear interactions undergone by the primary ions. Furthermore, the fragments generated in nuclear interactions can give rise to a fragmentation tail after the Bragg peak and contribute to the quality of the mixed radiation field. Therefore, experimental data about the total nuclear cross-section and fragment distributions for 4He beams are needed to develop and validate the models available for 4He-induced nuclear reactions with the same level of reliability achieved for other ion species (e.g. 12C). The aim of this work is to present novel fragmentation data [6] , in particular mass-changing cross-sections for 4He+12C collisions over the entire energy range relevant for therapy, and to compare them with the 4He-nucleus reaction models currently under development for FLUKA. The presented work will have the potential to improve significantly the dose calculation for helium ion therapy and ensure that future basic data will be as reliable as possible.