From track structure to biological endpoints: models, codes and MC simulations to investigate radiation action and damage formation

The investigation of the action of ionising radiation on biological structures requires a detailed analysis of the various stages underlying damage induction and evolution. In order to take into account the stochastic aspects characterising the process of interest, "ab initio" models and MC simulation codes are required, which start from the physical track structure and follow its time evolution, taking into account the various levels of organisation of the biological targets (DNA, chromosomes etc.). Representative examples of the activities in this area of the Universities of Milan and Pavia will be presented, focusing on the development of models aimed: a) to better understand the action mechanisms of ionising radiation, in the framework of the EC project "Low Dose Risk Models" coordinated by the GSF Institute of Munich; b) to study the induction of chromosome aberrations and their possible use as biomarkers, mainly in the framework of the INFN experiment "DOSBI", developed in collaboration with the University of Naples; c) to provide basic data for applicative tools developed for hadron therapy and space radiation protection, in the framework of the INFN projects "ATER.FIBI" and "FLUKA" and the ASI (Italian Space Agency) project "Influence of the shielding in the space radiation biological effectiveness".