Role of DNA organisation and environmental conditions in the evolutions of radiobiological damage: models and simulations

Background and purpose: Theoretical models and Monte Carlo simulations were developed, aimed to investigate the role played by the organisation of interphase DNA and the environmental scavenging capacity conditions in the induction of radiobiological damage. Methods: The induction of single- and double-strand breaks by gamma rays impinging on different DNA structures (e.g. linear DNA, SV4O minichromosome and cellular DNA) was simulated as a function of the environment scavenging capacity. Furthermore, yields of chromosome aberrations (CA) induced by gamma rays and light ions were simulated with a purposely developed MC code that expiicitly takes into account the DNA higher-order organisation as chromosome territories. Results and Conclusions: Simulations performed with the PARTRAC code allowed quantification of the dependence of dsb and ssb both on the target structure, and on the scavenging capacity. The results relative to CA showed the importance of DNA damage complexity (nanometre scale) and interphase chromosome domains (micrometre scale) in the process of aberration formation. Very good agreement was found between the model predictions on ssb, dsb and CA and available experimental data.