Research Of Impact Factors Of Nanodosimetric DNA Model

As we know from the Target Theory, the radiation damage to human highlydepend on the damage to DNA in cell nuclear, so it is very important to study theinfluence to DNA caused by radiation. The development of nanodosimetry and MonteCarlo method in recent decades make it possible to study the energy deposition ofionization radiation in DNA level. If we can combine nanodosimetry and Monte Carlowith suitable DNA model, it will be great helpful to research the mechanisms ofradiation damage. Therefore, building a correct and reasonable DNA model is of greatsignificance.Objective: There are many aspects need to be thought over in construction a DNAmodel. This paper is to study the impact of the three factors, the shape of nuclear, thelength of chromatin fibers and the distribution of DNA in nuclear, on DNA model,hoping to lay some theoretical foundation for building a more sophisticatednanodosimetric DNAmodel.Materials and Methods: Build corresponding geometry models and registerGeant4-DNA physical process in Geant4program, Simulate particle transportprocesses in these models, acquire interaction sites, use DBSCAN algorithm toanalysis characteristics of energy deposition of particles in the models, then come tothe influences of different impact on DNAmodels.Results: Nucleuses of sphere and ellipsoid have similar average chord length,there specific energy, linear energy, sites of DNA injury, the distribution of clusters, theaverage size of clusters and distribution of all kinds of injury are similar, too.Cylindrical nucleus’average chord length is smaller than the first two, compared with them, the specific energy, DNA damage sites, the distribution of clusters anddistribution of all kinds damage in nucleus are less, but linear energy, the average sizeof clusters and DSB/SSB are approximately equal;The change of chromatin fiber length has almost no influence on sites of DNAinjury, distribution of clusters, sizes of clusters and distribution of all kinds of DNAdamage when chromatin fiber length is at0.1μm~5.16μm;The distribution of DNA in nucleus has great influence on the sites and kinds ofDNA injury. When DNA is close to nuclear center, the number of sites of injury,clusters of injury, clusters of different sizes, the generation of all kinds of injury willincrease. But this factor has little effect on average cluster size of injury and DSB/SSB.Conclusion: This subject lays some theoretical foundation for the construction ofnanodosimetric DNA model. We need to bing model into correspondence with real cellin the shape of cell nucleus and the distribution of DNA in nucleus. If there aredifferences between the results of model calculations and experimental data, we can tryto adjust the shape of nucleus and the distribution of DNA in the nucleus. Chromatinfiber length has little effect on the nanodosimetric DNA model.