2016
Pater, Piotr; Bäckstöm, Gloria; Villegas, Fernanda; Ahnesjö, Anders; Enger, Shirin A.; Seuntjens, Jan; Naqa, Issam El
Proton and light ion RBE for the induction of direct DNA double strand breaks Journal Article
In: Medical Physics, vol. 43, no. 5, pp. 2131–2140, 2016, ISSN: 2473-4209, (_eprint: https://aapm.onlinelibrary.wiley.com/doi/pdf/10.1118/1.4944870).
Abstract | Links | BibTeX | Tags: biological effects of ionising particles, biomolecular effects of radiation, Cell Nucleus, cell nucleus model, cellular effects of radiation, DNA, DNA double-strand breaks, Dosimetry, Dosimetry/exposure assessment, Energy transfer, Genomics, Ion beams, Ion radiation effects, Monte Carlo calculations, Monte Carlo methods, Monte Carlo simulations, Monte Carlo track structure, Protons, RBE, Schottky barriers, Scintigraphy
@article{pater_proton_2016b,
title = {Proton and light ion RBE for the induction of direct DNA double strand breaks},
author = {Piotr Pater and Gloria Bäckstöm and Fernanda Villegas and Anders Ahnesjö and Shirin A. Enger and Jan Seuntjens and Issam El Naqa},
url = {https://aapm.onlinelibrary.wiley.com/doi/abs/10.1118/1.4944870},
doi = {10.1118/1.4944870},
issn = {2473-4209},
year = {2016},
date = {2016-01-01},
urldate = {2021-09-07},
journal = {Medical Physics},
volume = {43},
number = {5},
pages = {2131--2140},
abstract = {Purpose: To present and characterize a Monte Carlo (MC) tool for the simulation of the relative biological effectiveness for the induction of direct DNA double strand breaks () for protons and light ions. Methods: The MC tool uses a pregenerated event-by-event tracks library of protons and light ions that are overlaid on a cell nucleus model. The cell nucleus model is a cylindrical arrangement of nucleosome structures consisting of 198 DNA base pairs. An algorithm relying on k-dimensional trees and cylindrical symmetries is used to search coincidences of energy deposition sites with volumes corresponding to the sugar–phosphate backbone of the DNA molecule. Strand breaks (SBs) are scored when energy higher than a threshold is reached in these volumes. Based on the number of affected strands, they are categorized into either single strand break (SSB) or double strand break (DSB) lesions. The number of SBs composing each lesion (i.e., its size) is also recorded. is obtained by taking the ratio of DSB yields of a given radiation field to a 60Co field. The MC tool was used to obtain SSB yields, DSB yields, and as a function of linear energy transfer (LET) for protons (1H+), 4He2+, 7Li3+, and 12C6+ ions. Results: For protons, the SSB yields decreased and the DSB yields increased with LET. At ≈24.5 keV μm−1, protons generated 15% more DSBs than 12C6+ ions. The varied between 1.24 and 1.77 for proton fields between 8.5 and 30.2 keV μm−1, and it was higher for iso-LET ions with lowest atomic number. The SSB and DSB lesion sizes showed significant differences for all radiation fields. Generally, the yields of SSB lesions of sizes ≥2 and the yields of DSB lesions of sizes ≥3 increased with LET and increased for iso-LET ions of lower atomic number. On the other hand, the ratios of SSB to DSB lesions of sizes 2–4 did not show variability with LET nor projectile atomic number, suggesting that these metrics are independent of the radiation quality. Finally, a variance of up to 8% in the DSB yields was observed as a function of the particle incidence angle on the cell nucleus. This simulation effect is due to the preferential alignment of ion tracks with the DNA nucleosomes at specific angles. Conclusions: The MC tool can predict SSB and DSB yields for light ions of various LET and estimate . In addition, it can calculate the frequencies of different DNA lesion sizes, which is of interest in the context of biologically relevant absolute dosimetry of particle beams.},
note = {_eprint: https://aapm.onlinelibrary.wiley.com/doi/pdf/10.1118/1.4944870},
keywords = {biological effects of ionising particles, biomolecular effects of radiation, Cell Nucleus, cell nucleus model, cellular effects of radiation, DNA, DNA double-strand breaks, Dosimetry, Dosimetry/exposure assessment, Energy transfer, Genomics, Ion beams, Ion radiation effects, Monte Carlo calculations, Monte Carlo methods, Monte Carlo simulations, Monte Carlo track structure, Protons, RBE, Schottky barriers, Scintigraphy},
pubstate = {published},
tppubtype = {article}
}
Purpose: To present and characterize a Monte Carlo (MC) tool for the simulation of the relative biological effectiveness for the induction of direct DNA double strand breaks () for protons and light ions. Methods: The MC tool uses a pregenerated event-by-event tracks library of protons and light ions that are overlaid on a cell nucleus model. The cell nucleus model is a cylindrical arrangement of nucleosome structures consisting of 198 DNA base pairs. An algorithm relying on k-dimensional trees and cylindrical symmetries is used to search coincidences of energy deposition sites with volumes corresponding to the sugar–phosphate backbone of the DNA molecule. Strand breaks (SBs) are scored when energy higher than a threshold is reached in these volumes. Based on the number of affected strands, they are categorized into either single strand break (SSB) or double strand break (DSB) lesions. The number of SBs composing each lesion (i.e., its size) is also recorded. is obtained by taking the ratio of DSB yields of a given radiation field to a 60Co field. The MC tool was used to obtain SSB yields, DSB yields, and as a function of linear energy transfer (LET) for protons (1H+), 4He2+, 7Li3+, and 12C6+ ions. Results: For protons, the SSB yields decreased and the DSB yields increased with LET. At ≈24.5 keV μm−1, protons generated 15% more DSBs than 12C6+ ions. The varied between 1.24 and 1.77 for proton fields between 8.5 and 30.2 keV μm−1, and it was higher for iso-LET ions with lowest atomic number. The SSB and DSB lesion sizes showed significant differences for all radiation fields. Generally, the yields of SSB lesions of sizes ≥2 and the yields of DSB lesions of sizes ≥3 increased with LET and increased for iso-LET ions of lower atomic number. On the other hand, the ratios of SSB to DSB lesions of sizes 2–4 did not show variability with LET nor projectile atomic number, suggesting that these metrics are independent of the radiation quality. Finally, a variance of up to 8% in the DSB yields was observed as a function of the particle incidence angle on the cell nucleus. This simulation effect is due to the preferential alignment of ion tracks with the DNA nucleosomes at specific angles. Conclusions: The MC tool can predict SSB and DSB yields for light ions of various LET and estimate . In addition, it can calculate the frequencies of different DNA lesion sizes, which is of interest in the context of biologically relevant absolute dosimetry of particle beams.