Monte Carlo nuclear models evaluation and improvements for real-time prompt gamma ray monitoring in proton and carbon therapy

Accurate Monte Carlo simulations are essential both for the development of an optimized detection array that will be used in clinical practice for precise ion beam range monitoring. Within GEANT4, both the Quantum Molecular Dynamics (QMD) and the Binary Cascade (BIC) models overestimate the overall prompt-gamma depth profile yields measured with carbon ion and proton beams. By optimizing the selection of free parameters of the models, better agreement with the data is obtained for low energy carbon beams (main gamma component by ion-ion collisions) as well as for proton beams and high energy carbon beams (main gamma component by nucleon-nucleus collisions).