Research On Nanodosimetry DNA Damage And Repair Module Based On The DNA Atomic Model

The radiation damage of DNA in the nucleus is the most basic and the most important primary injury causing all theradiation biological effects.To study the radiation biological effect of nuclear DNA irradiated by different particle types and energies,the Monte Carlo method is applied to the simulation study of radiation induced DNA damagewith reference to the international nanodosimetry Monte Carlo program.At the guidance of the theory of biology theory,DNA damage module and DNA repair module of DNA atomic model has been developed based on the existing Nanodosimetry Monte Carlo Simulation Code(NASIC)of DNAvolume model.The main work of this dissertation includes:(1)The construction of DNA damage module of the DNA atomic model.DNA damage model can simulate the direct damage caused by the direct radiation of DNA,and the indirect damage of DNA caused by ·OH radicalsin the cellular water environment induced by radiationbased on the DNA atomic model.The yields of single strand breaks(SSB),double strand breaks(DSB)and base damage(BD)after the irradiation of nuclear DNA with137 Cs and Alkphotons were calculated and compared with the experimentresults.It showed that the yields of SSB,DSB and BD were in good agreement with the experiment data,and other evaluation data of damage results were also in the reference value range.(2)The construction of DNA repair module.DNA repair modulecan simulate theNon-homologous End Joining(NHEJ)repair process of DSB,which is easy to cause the chromosome aberration.Therepair curve andchromosome aberration yields afterthe irradiation of nuclear DNA withlow doses of gamma rays were calculated and compared with the experimentresults.It showed that the repair time-fraction of residual DSB curve andthe acentric,dicentric yields were in the expetiment value range.In this dissertation,the first domesticnanodosimetry Monte Carlo code that could simulate the DNA damage and repair process was established.An evaluation method from the radiation to the chromosome aberration was established at the nanoscale.The study provided a reference for the simulation of biological effects of low dose radiation.