Preliminary results in using Deep Learning to emulate BLOB, a nuclear interaction model

PURPOSE

A reliable model to simulate nuclear interactions is fundamental for Ion-therapy. We already showed how BLOB ("Boltzmann-Langevin One Body"), a model developed to simulate heavy ion interactions up to few hundreds of MeV/u, could simulate also ¹²C reactions in the same energy domain. However, its computation time is too long for any medical application. For this reason we present the possibility of emulating it with a Deep Learning algorithm.

METHODS

The BLOB final state is a Probability Density Function (PDF) of finding a nucleon in a position of the phase space. We discretised this PDF and trained a Variational Auto-Encoder (VAE) to reproduce such a discrete PDF. As a proof of concept, we developed and trained a VAE to emulate BLOB in simulating the interactions of ¹²C with ¹²C at 62 MeV/u. To have more control on the generation, we forced the VAE latent space to be organised with respect to the impact parameter (b) training a classifier of b jointly with the VAE.

RESULTS

The distributions obtained from the VAE are similar to the input ones and the computation time needed to use the VAE as a generator is negligible.

CONCLUSIONS

We show that it is possible to use a Deep Learning approach to emulate a model developed to simulate nuclear reactions in the energy range of interest for Ion-therapy. We foresee the implementation of the generation part in C++ and to interface it with the most used Monte Carlo toolkit: Geant4.

Production of the PET isotope 11C in hadron therapy via neutron knockout

PURPOSE

Positron emitting isotopes such as ¹¹C and ¹⁰C can be used for vital dose verification in hadron therapy. These isotopes are produced when the high energy ¹²C primary beam particles undergo nuclear reactions within the patient.

METHODS

We discuss a model for calculating cross sections for the production ¹¹C in ¹²C+¹²C collisions, applicable at hadron therapy energies.

RESULTS

Good agreement with the available cross section measurements is found for ¹²C(-1n), though more detailed, systematic measurements would be very valuable.

CONCLUSIONS

Nuclear structure plays a crucial role in the reactions of light nuclei, particularly when those reactions are peripheral and involve only a few nucleons. For such reactions, nuclear structure has a strong influence on the energy and angular distribution of the cross section, and is an important consideration for reliable dose verification using ¹¹C in hadron therapy.