Benchmarking micro- and nanodosimetry spectra and free radicals simulated with GEANT4DNA, LQD, PHYCHEML, CHEM for ion beams
Résumé
Introduction.
To optimize hadrontherapy treatments, the relative biological effectiveness (RBE) needs to be estimated through biophysical models. The Microdosimetric Kinetic Model (MKM) [1] and the Nanodosimetry Oxidative stress model (NanOx) [2] rely on the calculation of the specific energy spectra at nano- and micrometric scales. The NanOx model introduces also the concept of chemical specific energy based on the production of free radicals. This study proposes to benchmark GEANT4-DNA and LQD/PHYCHEML/CHEM specific energy and lineal energy spectra simulations and the yields of primary species induced by water radiolysis. Physical and chemical data are estimated for protons and carbon ions monoenergetic beams.
Material and Methods.
The ion tracks in water are simulated using GEANT4-DNA. The three dimensions energy transfer points analyzed with the TED code is used to calculate the specific energy and the lineal energy spectra in micro and nanometric targets. Radiochemical products (e-aq, OH., H2O2., O2-.) are calculated with the chemistry module of GEANT4-DNA and with PHYCHEML and CHEM codes for LQD. Same quantities are then evaluated for SOBP through the superposition of monoenergetic ion tracks.
Results.
The comparison of the results issued from GEANT4-DNA and LQD will be presented for monoenergetic beams. Results obtained for SOBP will also be shown. This study is preliminary to a full implementation of the MKM and NanOx models into the GATE platform.
Bibliography
1. Hawkins RB. Med Phys. 1998;25: 1157–1170.
2. Cunha M, et al. PMB, 2017;62:1248-1268.