Use this URL to cite or link to this record in EThOS:
Title: Computational modelling of DNA-damage induced by low-level ionising radiation
Author: Alsalili, G. G.
Awarding Body: University of Wales Swansea
Current Institution: Swansea University
Date of Award: 2003
Availability of Full Text:
Access from EThOS:
Most of the detrimental effects of ionising radiation in biology, such as cell killing and mutation, result from double strand break in DNA. To help in understanding their mechanism of formation, biophysical modelling of DNA damage at a sub-cellular level has been carried out. A Monte Carlo program was written in Fortran 77 to simulate the exposure of a cellular system (biological structure model) to ionising radiation. The model evaluates the physical effect of the ionisation and excitation processes in three stages: (1) simulating the physical data using an event-by-event Monte Carlo track structure code TRAX, (2) calculating the distances between these events and their distribution, and (3) assigning reaction probabilities to the parameters in the survival model. The objective of this work is to highlight the important factors that should be included in any model of cell survival, namely the degree of detail required for the DNA and the track structure. For this purpose, two models of energy deposition were considered (random independent hits and structured tracks) combined with two models of DNA (homogeneously-distributed and “nucleosome cyclinder”). It was found that the homogeneous DNA model was not able to give good agreement with measured cell survival data, using either random hits or hits distributed along tracks. On the other hand, the nucleosome DNA model with the correct track structure provided a better fit to a family of experimental survival curves over a range of dose rates. Therefore it is essential to consider some structure to the DNA, together with a correct model for the tracks. In addition the combination of the nucleosome cylinder DNA model with track structure gave results that were compatible with experimental estimates of the numbers of single-strand and double-strand breaks per cell per Gy, and the ratio between these quantities.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available