Using Theoretical Calculations Of Track Structure Method Simulated Monoenergetic Electron Induced Dna Of Early Injury

There are two main types of radiobiological effects, deterministic and stochastic effects, which concern radiation protection community. DNA molecular is the main carrier of heredity information. Its damage will induce the changing or missing of heredity information of organism directly. If the damage can't be repaired effectively and timely, it will lead to the mutation and apoptosis of cell. Over the past half-century, the important concerns to radiobiology scholars are the quantification of health hazards of ionizing radiation of different quality, and the reliability of human cancer risk from high-dose, dose rate extrapolation to low-dose, dose rate. With the rapid technological progress of molecular biology and the development of theoretical methods, the research and explanation of mechanism of ionizing radiation biology effects have become the focus of attention gradually over the past ten years. Track structure method is a theoretical foundation for understanding the basic mechanism of radiation damage. It follows the "track" of various particles (including electron, proton of physical particles and radical of chemical particles), and provides a powerful tool to explore those parameters affecting the ultimate biological effects of ionizing radiation.The track structure method is used to model the early physical and chemical event from the incidence of monoenergetic electrons (10eV - 100keV) to DNA solution to the production of final DNA-damage in this paper. The meaning of so-called "early" refers to the stage before DNA repair, namely the physical and chemical stage, within about 10^-5s. The specific research topics are: 1) using M0CA15 code to calculate track distribution of certain energy electrons in aqueous media, and generating of the energy deposition of each event and the distribution of ionization and excitation of water molecular, 2) generating the distribution of free radicals in aqueous solution with the data of ionization and excitation data, 3) establishing the overall model and the fine structure model of DNA for simulation, 4) on the basis of this model, considering direct energy deposition and the free radical impacting and injuring DNA; 5) classifying the DNA damage, and generating the data of damage of all kinds to assess the biological effect induced by radiation.The research content of this paper is the modeling of the physical and chemical stage of low-energy electron-induced DNA damage with calculation program coded by C# computer language. The final production is the basic data of DNA damage, which contains the yield of double-strand break (DSB), single-strand break (SSB), and base damage (BD), and the analysis and comparison of the data. Through the analysis of the results, the following conclusions were drawn: 1) The majority of interactions in DNA don't cause damage and are in the form of no break, most of the strand breaks are the SSBs which are easy to repair; 2) In a small number of DSBs, the complex DSBs accounted for a considerable number of shares (30% -50%); 3) From the source of injury, indirect damage accounts for a sizeable share, in particularly, makes a great contribution for constituting DSB; 4) According to the compare between results of theoretical calculations and experimental data, the basic assumption, DNA is the main target of radiation reaction, is validated. It has also discussed the challenge of the classical theory of the target from new phenomenon of genomic instability, bystander effect, and adaptable response in radiobiology in this paper.