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Electron beam therpy is used to treat tumor cells by irradiation with high energy electrons (HEE). The irradiation is performed by medical linear accelerators.
By interaction of the HEE with the irradiated tissue a broad spectra of secondary electrons and water dissoziation products is generated.
These products interact with biomolecules, especially DNA, by various processes. The disentanglement of the resulting direct- and indirect damage to DNA and other cellular components is still under debate.
To increase the efficiency of future therapies a better understanding of the microscopic damaging processes is highly important.
Especially the various contributions of the secondary species produced, such as low energy electrons (LEE) and radicals is far from understood and quantified.
To increase the understanding we present a combination of a microdosimetric simulations and experiments to quantify the damage by means of electron scattering and diffusion simulations within the Geant4-DNA framework.
In combination with in-liquid irradiation of plasmid DNA it possible to determine microdosimetric quantities for biomolecules in liquid environment.
The presented method was applied to the irradiation of plasmid DNA (pUC19) in water.
This opens up new possibilities in radiation research to quantify the dosage-damage relationship for microscopic plasmid volumes under well defined physiological condition.
The damage caused by ionizing radiation to biomolecules, especially DNA, is the reason to treat cancer via radiation therapy. A better understanding of the molecular processes and the quantification of the various damaging mechanisms is the prerequisit to develope efficient therapies. Hereby the understanding of the processes involved in the damage to DNA are of key interest due to its central role in reproduction and mutation. Due to the high amount of water in biological tissue, most of the damage is caused by the secondary particles produced by the interaction of the IR with water. Thereby a multitude of species are produced, e.g. kinetic low energy electrons, prehydrated electrons, OH-radicals and ions. The quantification of the contribution to DNA damage of the various species is of interest. Here we present an experimental approach to disentangle their relative DNA strand break yield. Plasmid DNA is irradiated in water with electrons under the presence of different scavengers. With the presented method it will be possible to reveal the relative contributions of OH-radicals, low energy electrons and prehydrated electrons to the DNA single and double strand break yield.