Validation of Geant4 Nuclear Reaction Models for Hadron Therapy and Preliminary Results with BLOB

Abstract

Reliable nuclear fragmentation models are of utmost importance in hadron therapy, where Monte Carlo (MC) simulations are used to compute the input parameters of the treatment planning software, to validate the deposited dose calculation, to evaluate the biological effectiveness of the radiation, to correlate the $\beta +$ emitters production in the patient body with the delivered dose, and to allow a non-invasive treatment verification. Despite of its large use, the models implemented in Geant4 have shown severe limitations in reproducing the measured secondaries yields in ions interaction below 100 MeV/A, in term of production rates, angular and energy distributions. We present a benchmark of the Geant4 models with double-differential cross section of the secondary fragments produced in the $^{12} {\text{C}}$ fragmentation at 62 MeV/A on thin carbon target. Such a benchmark includes the recently implemented model “Liège Intranuclear Cascade’’. Moreover, we present the preliminary results, obtained in simulating the same interaction, with the “Boltzmann-Langevin One Body’’ model (BLOB). BLOB is a semiclassical one-body approaches to solve the Boltzmann-Langevin equation. It includes a mean-field propagation term, on the basis of an effective interaction. In addition to the mean field term, BLOB introduces fluctuations in full phase space through a modified collision term where nucleon-nucleon correlations are explicitly involved. It has been developed to simulate the heavy ion interactions in the Fermi-energy regime. In this work, we show the BLOB capabilities in describing $^{12} {\text{C}}$ fragmentation, in the perspective of a direct implementation in Geant4. Monte Carlo simulation, nuclear interaction, nuclear fragmentation, hadron therapy.