Biophysical modelisation of gold nanoparticles radiosensi-tizing effects
Résumé
The main challenge of radiotherapy is to focus the irradiation dose in cancer cells while preserving the healthy cells surrounding the tumor. Among the different strategies, the use of radiosensitizers aims to amplify the destructive effects of dose in the tumor1. Nanoparticles of heavy metals such as gold and gadolinium, are particularly promising radiosensitizers. If their radiosensitizer effect has been studied for about two decades, the origin of this phenomenon is yet quite unknown and barely quantified.
Litterature suggests that irradiation would generate a physical effect called Auger cascades. This effect would lead to a local increase secondary electrons around the nanoparticle, thus implifying the critical cell damages of direct sensible molecules such as DNA, or through a boost of free radicals. These effects are produced at nanometric scales and at very short time (10-15 to 10-12 seconds) but have consequences on the patient scale.
Because this physical and chemical effects are not directly observable, the simulation tool is therefore mendatory to better understand the initial mecanisms. Our goal is to first develop a simulation that enables us to calculate the spatial dose and free radicals distribution around the nanoparticles, and to quantify the induced boost2,3. Secondly, we want to inject the results in the model Nanox4, originally developed in IPNL to calculate the biological dose in hadron-therapy.
These two allow us to assess the the quality of our models, and the relevance of the scenarii offered in literature. The final aim is to guide the development of the nanoparticles and, if possible, to help to planify clinical treatment of nanoparticle-based radiotherapy.