Re-engineering a nanodosimetry Monte Carlo code into Geant4: software design and first results

Microbeam Radiation Therapy (MRT) is an innovative experimental technique potentially able to overcome the limitations of conventional radiotherapy for infantile brain tumors. Its effectiveness seems to be related to the ability of normal tissues to tolerate a very high radiation dose in small volumes, resulting in the preservation of the tissues' architecture. The effectiveness of MRT is well represented by peak-to-valley dose ratios (PVDRs), which are one of the crucial parameters associated with the outcome of the treatment. We present Geant4 Monte Carlo calculations of the dose distribution deposited by planar polarized microbeams with micrometric resolution. The simulation of the beam polarization, made possible by different libraries included in Geant4, is a crucial step in enhancing the comparability of experimental data and simulation results.