Titolo della tesi: Development of tools for quality control on therapeutic carbon beams with a fast-MC code (FRED)
In this thesis, the development of a fast MC simulating the carbon treatment in particle therapy, with an entirely new nuclear interaction model of carbon on light target nuclei, has been presented. The model has been developed to be implemented in the GPU based MC code, FRED. For this reason, in developing the algorithms the goal has been to balance accuracy, calculation time and GPU execution guidelines. In particular, maximum attention has been given to physical processes relevant for dose and biological dose computation. Moreover, where possible, look-up tables have been implemented instead of performing an explicit calculation in view of the GPU implementation. Some aspects of the interaction of carbon ions with matter are analogous to the ones already used in FRED for proton beams. In particular, for ionization energy loss and multiple scattering, only a few adjustments were necessary. On the contrary, the nuclear model was built from scratch. The approach has been to develop the nuclear model parameterizing existent data and applying physical driver scaling in the energy range where the data are missing. The elastic cross-section has been obtained from ENDF/B-VII data while the calculation of the non-elastic cross-section was based on results reported on Tacheki, Zhang and Kox papers. Data used for the sampling of the combination of emitted fragments, energy and angle distributions, are relatives to the Dudouet and Divay experiments (Ganil experiment). To fill the gaps in the experimental data, an intercomparison between FRED and the full-MC FLUKA has been of help to check the adopted scaling. The implementation of the LEM model for the calculation of the biological dose and RBE has been presented as well. This calculation is of fundamental importance for the application of the fast-MC code FRED in clinical practice. The user can easily change the and parameters of the LEM model substituting an input table. In this way, it will be possible to use the parameters decided by the specific medical structure. The model has been tested against the full-MC code FLUKA, commonly used in particle therapy, and then with two of the few experiments that it is possible to find in literature.