Numerical Models for Radiation-induced DNA Damage

Download or read book Numerical Models for Radiation-induced DNA Damage written by Piotr Pater and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: "This thesis introduces and explores various numerical models for calculating DNA damage produced by photons, electrons, protons, and other light ion beams. Clustered DNA damage in the form of single-strand and double-strand breaks are a hallmark of radiation and a known initiating agent of loss of cellular reproductive ability. A rigorous analysis of the Monte Carlo track structure calculation methodology is presented with emphasis put on standardization of the definitions, values, and algorithms relating the various adjustable parameters in the model. Commonly overlooked problems associated with the strand break threshold energy, the clustering algorithm, the impact of the dose distribution, and the lack of charged particle equilibrium are presented. Estimates of nucleosome strand breakage clustering are obtained to highlight the higher damage complexity of lower kinetic energy electron beams. The algorithms presented offer innovative and fast DNA damage induction searches inside geometrical models of the complete human DNA genome of a biological cell nucleus. Strand break yields induced by proton and light ion beams are described and quantified with respect to the linear energy transfer (LET). It was found that protons create statistically more double-strand breaks than carbon ions of the same LET. In these simulations, computation time places a fundamental limit on the level of detail simulated; however, the data presented shows that the radiation field affecting the nuclear DNA needsto be described with precision in order to reproduce clinical irradiation setups. Firstly, an introduction to the track overlay algorithm built upon a pre-generated library of electron tracks obtained from a precise description of the photon field experienced around a cell nucleus is presented. Subsequently, an analysis was performed to quantify the creation of double-strand breaks by clinical photon fields, including cone-beam computed-tomography, electronic brachytherapy, and several radio-isotopes. Lastly, the effectiveness at inducing double-strand breaks are computed using the relative biological effectiveness metric. This is complemented by an investigation of the trends of this quantity with respect to particle type and energy." --