Quantitative modelling of DNA damage using Monte Carlo track structure method

Nikjoo, Hooshang; O’Neill, Peter; Terrissol, M.; Goodhead, Dudley T.

doi:10.1007/s004110050135

Cited by 296 publications

(160 citation statements)

References 52 publications

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“…[1][2][3] The electron ionization processes play a dominant role in this as the number of electrons increases through the cascading process of ionization. The quantitative data on these processes are essential inputs to Monte Carlo particle track structure simulations 4 that are widely used to understand the radiation damage in biological systems and for application to microdosimetry, nano-dosimetry, 5,6 and radiation therapy. 7 The data involve a complete set of total and partial cross sections for the respective primary and secondary particles and target molecules.…”

mentioning

confidence: 99%

Communication: Electron ionization of DNA bases

Rahman

Krishnakumar

2016

The Journal of Chemical Physics

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No reliable experimental data exist for the partial and total electron ionization cross sections for DNA bases, which are very crucial for modeling radiation damage in genetic material of living cell. We have measured a complete set of absolute partial electron ionization cross sections up to 500 eV for DNA bases for the first time by using the relative flow technique. These partial cross sections are summed to obtain total ion cross sections for all the four bases and are compared with the existing theoretical calculations and the only set of measured absolute cross sections. Our measurements clearly resolve the existing discrepancy between the theoretical and experimental results, thereby providing for the first time reliable numbers for partial and total ion cross sections for these molecules. The results on fragmentation analysis of adenine supports the theory of its formation in space.

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confidence: 99%

Communication: Electron ionization of DNA bases

Rahman

Krishnakumar

2016

The Journal of Chemical Physics

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“…Track structure simulations [12,13] have predicted clustering of these lesions over distances of 10 nm or less and, more recently, experimental evidence has supported this prediction [14,15].…”

Section: Ionization Clusters and Complex Dna Damagementioning

confidence: 92%

Ion-counting nanodosimetry: current status and future applications

Schulte

Bashkirov

Garty

et al. 2003

Australas. Phys. Eng. Sci. Med.

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There is a growing interest in the study of interactions of ionizing radiation with condensed matter at the nanometer level. The motivation for this research is the hypothesis that the number of ionizations occurring within short segments of DNA-size subvolumes is a major factor determining the biological effectiveness of ionizing radiation. A novel dosimetry technique, called nanodosimetry, measures the spatial distribution of individual ionizations in an irradiated lowpressure gas model of DNA. The measurement of nanodosimetric event size spectra may enable improved characterization of radiation quality, with applications in proton and charged-particle therapy, radiation protection, and space research. We describe an ion-counting nanodosimeter developed for measuring radiation-induced ionization clusters in small, wall-less low-pressure gas volumes, simulating short DNA segments. It measures individual radiation-induced ions, deposited in 1 Torr propane within a tissue-equivalent cylindrical volume of 2-4 nm diameter and up to 100 nm length. We present ionization cluster size distributions obtained with 13.6 MeV protons, 4.25 MeV alpha particles and 24.8 MeV carbon nuclei in propane; they correspond to a wide LET range of 4-500 keV/micron. We are currently developing plasmid-based assays to characterize the local clustering of DNA damage with biological methods. Systematic comparison of biological and nanodosimetric data will help us to validate biophysical models predicting radiation quality based on nanodosimetric spectra. Possible applications for charged particle radiation therapy planning are discussed.

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“…The number of past studies and endpoints used are limited if viewed as surrogate endpoints for human carcinogenesis. Track structure models suggest that each ion species would have distinct RBE curves of similar shape, however with curves for lower charge ions peaking at a lower LET than higher charged ions (Katz et al, 1971;Cucinotta et al, 1996;Nikjoo et al, 1999). Furthermore, above about 1-MeV/u, lower charged ions have a higher biological effectiveness than higher charged ions of identical LET.…”

Section: Uncertainties Due To Radiation Quality Effectsmentioning

confidence: 99%

Evaluating shielding effectiveness for reducing space radiation cancer risks

Cucinotta

Kim

Ren³

2006

Radiation Measurements

127

118

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Abstract:We discuss calculations of probability distribution functions (PDF) representing uncertainties in projecting fatal cancer risk from galactic cosmic rays (GCR) and solar particle events (SPE). The PDF's are used in significance tests of the effectiveness of potential radiation shielding approaches. Uncertainties in risk coefficients determined from epidemiology data, dose and dose-rate reduction factors, quality factors, and physics models of radiation environments are considered in models of cancer risk PDF's. Competing mortality risks and functional correlations in radiation quality factor uncertainties are treated in the calculations. We show that the cancer risk uncertainty, defined as the ratio of the 95% confidence level (CL) to the point estimate is about 4-fold for lunar and Mars mission risk projections. For short-stay lunar missions (<180 d), SPE's present the most significant risk, however one that is mitigated effectively by shielding, especially for carbon composites structures with high hydrogen content. In contrast, for long duration lunar (>180 d) or Mars missions, GCR risks may exceed radiation risk limits, with 95% CL's exceeding 10% fatal risk for males and females on a Mars mission. For reducing GCR cancer risks, shielding materials are marginally effective because of the penetrating nature of GCR and secondary radiation produced in tissue by relativistic particles. At the present time, polyethylene or carbon composite shielding can not be shown to significantly reduce risk compared to aluminum shielding based on a significance test that accounts for radiobiology uncertainties in GCR risk projection.

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Quantitative modelling of DNA damage using Monte Carlo track structure method

Cited by 296 publications

References 52 publications

Communication: Electron ionization of DNA bases

Communication: Electron ionization of DNA bases

Ion-counting nanodosimetry: current status and future applications

Evaluating shielding effectiveness for reducing space radiation cancer risks

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