International audienceRationale : An alternative approach for the improvement of radiotherapy consists in increasing differentially the radiation dose between tumors and normal tissues using nanoparticles (NPs) that have been beforehand internalized into the tumor. These high-Z NPs can be photo-activated by monochromatic synchrotron X-rays, leading to a local dose enhancement delivered to the neighbouring tumor cells. In this study, we evaluated the ability of iron NPs to act as radiosensitizers in vitro and through simulations.Materials and Methods : The radiosensitizing effect of Fe NPs was assessed through Monte Carlo simulations (PENELOPE) and in vitro experiments: F98 tumor cells were incubated for 24h with Fe NPs before being irradiat...