Track structure characterization and its link to radiobiology

摘要

AbstractWithin the Italian project MITRA (MIcrodosimetry andTRAck structure), funded by the ItalianIstitutoNazionale diFisicaNucleare (INFN), and the EMRP Joint Research Project “BioQuaRT” (Biologically WeightedQuantities inRadiotherapy), experiments have been carried out at the Tandem–Alpi accelerator facility of Legnaro National Laboratories (LNL), in which the frequency distribution of the number of ionisations produced by proton and carbon ion beams of given energy was measured with the PTB Ion Counter and the LNL StarTrack Counter. Descriptors of the track structure can be derived from these distribution; in particular, the first momentM1, representing the mean number of ionisations produced in the target volume, and the cumulative probabilitiesFkof measuring cluster sizes ν?≥?k.Experimental radiobiological data have been compared with nanodosimetric quantities derived from measured ionisation-cluster size distributions. It was found that the cumulative probabilitiesFkas a function ofM1behave in the same way as the inactivation cross sections as a function of LET, first increasing with increasing values ofM1and then showing a saturation effect.