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Computational and Mathematical Methods in Medicine
Volume 2012, Article ID 147252, 9 pages
Research Article

In Silico Nanodosimetry: New Insights into Nontargeted Biological Responses to Radiation

1School of Physics, University of Sydney, Sydney, NSW 2006, Australia
2Centre for Medical Radiation Physics, University of Woollongong, Wollongong, NSW 2522, Australia
3Department of Physics, Technical University of Munich, 85748 Garching, Germany
4Université Bordeaux 1, CNRS/IN2P3, Centre d'Etudes Nucléaires de Bordeaux-Gradignan, 33175 Gradignan, France

Received 21 February 2012; Accepted 2 April 2012

Academic Editor: Eva Bezak

Copyright © 2012 Zdenka Kuncic et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


The long-held view that radiation-induced biological damage must be initiated in the cell nucleus, either on or near DNA itself, is being confronted by mounting evidence to suggest otherwise. While the efficacy of cell death may be determined by radiation damage to nuclear DNA, a plethora of less deterministic biological responses has been observed when DNA is not targeted. These so-called nontargeted responses cannot be understood in the framework of DNA-centric radiobiological models; what is needed are new physically motivated models that address the damage-sensing signalling pathways triggered by the production of reactive free radicals. To this end, we have conducted a series of in silico experiments aimed at elucidating the underlying physical processes responsible for nontargeted biological responses to radiation. Our simulation studies implement new results on very low-energy electromagnetic interactions in liquid water (applicable down to nanoscales) and we also consider a realistic simulation of extranuclear microbeam irradiation of a cell. Our results support the idea that organelles with important functional roles, such as mitochondria and lysosomes, as well as membranes, are viable targets for ionizations and excitations, and their chemical composition and density are critical to determining the free radical yield and ensuing biological responses.