Comprehensive track-structure based evaluation of DNA damage by light ions from radiotherapy-relevant energies down to stopping

Track structures and resulting DNA damage in human cells have been simulated for hydrogen, helium, carbon, nitrogen, oxygen and neon ions with 0.25–256 MeV/u energy. The needed ion interaction cross sections have been scaled from those of hydrogen; Barkas scaling formula has been refined, extending...

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Bibliographic Details
Published in:Scientific reports 2017-03, Vol.7 (1), p.45161-45161, Article 45161
Main Authors: Friedland, W., Schmitt, E., Kundrát, P., Dingfelder, M., Baiocco, G., Barbieri, S., Ottolenghi, A.
Format: Article
Language:English
Subjects:
631/114/2397
631/1647/767
Carbon - chemistry
Carbon - pharmacology
Cell survival
Computer Simulation
Deoxyribonucleic acid
DNA
DNA - radiation effects
DNA Breaks, Double-Stranded
DNA damage
DNA structure
Double-strand break repair
Helium
Helium - chemistry
Helium - pharmacology
Humanities and Social Sciences
Humans
Ions
Light
Linear Energy Transfer
multidisciplinary
Neon - chemistry
Nuclei
Oxygen - chemistry
Oxygen - pharmacology
Phototherapy - adverse effects
Protons
Radiation therapy
Radiotherapy - adverse effects
Scaling
Science
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Summary:Track structures and resulting DNA damage in human cells have been simulated for hydrogen, helium, carbon, nitrogen, oxygen and neon ions with 0.25–256 MeV/u energy. The needed ion interaction cross sections have been scaled from those of hydrogen; Barkas scaling formula has been refined, extending its applicability down to about 10 keV/u, and validated against established stopping power data. Linear energy transfer (LET) has been scored from energy deposits in a cell nucleus; for very low-energy ions, it has been defined locally within thin slabs. The simulations show that protons and helium ions induce more DNA damage than heavier ions do at the same LET. With increasing LET, less DNA strand breaks are formed per unit dose, but due to their clustering the yields of double-strand breaks (DSB) increase, up to saturation around 300 keV/μm. Also individual DSB tend to cluster; DSB clusters peak around 500 keV/μm, while DSB multiplicities per cluster steadily increase with LET. Remarkably similar to patterns known from cell survival studies, LET-dependencies with pronounced maxima around 100–200 keV/μm occur on nanometre scale for sites that contain one or more DSB, and on micrometre scale for megabasepair-sized DNA fragments.
ISSN:2045-2322
2045-2322
DOI:10.1038/srep45161