Energy deposition in small cylindrical targets by ultrasoft X-rays

Nikjoo, Hooshang; Goodhead, Dudley T.; Charlton, D.E.; Paretzke, H. G.

doi:10.1088/0031-9155/34/6/005

Cited by 86 publications

(48 citation statements)

References 23 publications

(11 reference statements)

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“…The starting point of these and similar calculations [21] is simulating the track of the ionising particle, molecular interaction by interaction in DNA and water at 10 -15 s and establishing the initial distribution of water radicals at 10 -12 s. Currently, there are a number of computer codes available for the simulation of particle tracks [2]. These distributions are then used to obtain information on the nature of DNA damage induced by the ionising radiation.…”

Section: Methods Of Calculationmentioning

confidence: 99%

“…The database for the frequencies of energy deposition in a small volume corresponding to the biological targets for electrons, x-photons and ions, and the methods of the calculation can be found in various publications [22,[27][28][29]. The frequencies of energy deposition can also be generated using an algorithmic method [30].…”

Section: Calculation Of Dna Strand Breakagementioning

confidence: 99%

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Quantitative modelling of DNA damage using Monte Carlo track structure method

Nikjoo

O’Neill

Terrissol

et al. 1999

Radiation and Environmental Biophysics

297

147

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This paper presents data on modelling of DNA damage induced by electrons, protons and alpha-particles to provide an insight into factors which determine the biological effectiveness of radiations of high and low linear energy transfer (LET). These data include the yield of single- and double-strand breaks (ssb, dsb) and base damage in a cellular environment. We obtain a ratio of 4-15 for ssb:dsb for solid and cellular DNA and a preliminary ratio of about 2 for base damage to strand breakage. Data are also given on specific characteristics of damage at the DNA level in the form of clustered damage of varying complexity, that challenge the repair processes and if not processed adequately could lead to the observed biological effects. It is shown that nearly 30% of dsb are of complex form for low-LET radiation, solely by virtue of additional breaks, rising to about 70% for high-LET radiation. Inclusion of base damage increases the complex proportion to about 60% and 90% for low- and high-LET radiation, respectively. The data show a twofold increase in frequencies of complex dsb from low-LET radiation when base damage is taken into account. It is shown that most ssb induced by high-LET radiation have associated base damages, and also a substantial proportion is induced by low-energy electrons.

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Section: Methods Of Calculationmentioning

confidence: 99%

Section: Calculation Of Dna Strand Breakagementioning

confidence: 99%

Quantitative modelling of DNA damage using Monte Carlo track structure method

Nikjoo

O’Neill

Terrissol

et al. 1999

Radiation and Environmental Biophysics

297

147

View full text Add to dashboard Cite

show abstract

“…Among the variety of MCTS codes [5], the strategy consists in replicating and arranging an elementary piece of DNA to form structural levels. Usually, each elementary piece of DNA is represented either by a simple geometrical shape [6][7][8][9][10][11] or by a piece of DNA double helix in atomic resolution [1,[12][13][14][15].…”

Section: Introductionmentioning

confidence: 99%

PDB4DNA: Implementation of DNA geometry from the Protein Data Bank (PDB) description for Geant4-DNA Monte-Carlo simulations

Delage

Pham

Karamitros

et al. 2015

Computer Physics Communications

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International audienceThis paper describes PDB4DNA, a new Geant4 user application, based on an independent, cross-platform, free and open source C++ library, so-called PDBlib, which enables use of atomic level description of DNA molecule in Geant4 Monte Carlo particle transport simulations. For the evaluation 15 of direct damage induced on the DNA molecule by ionizing particles, the application makes use of an algorithm able to determine the closest atom in the DNA molecule to energy depositions. Both the PDB4DNA application and the PDBlib library are available as free and open sourc

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“…[6]), but the processing time required to execute a sufficient number of histories to yield results such as the energy deposited in a small volume with an acceptable uncertainty is prohibitive, even with today's powerful hardware. However, when the quantity of interest is the structure of the charged particle tracks, in order to understand, for example, the details of the interaction of radiation with the structures in the cells of living matter, then event-by-event MC codes are an essential tool [6,7,8,68].…”

Section: Electron Transport Schemesmentioning

confidence: 99%

Condensed-history Monte-Carlo simulation for charged particles: what can it do for us?

Nahum

1999

Radiation and Environmental Biophysics

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Condensed-history (CH) Monte-Carlo (MC) groups together the vast number of individual charged-particle collisions using multiple scattering theory for elastic angular changes and stopping power for energy losses. CH codes such as EGS4 have been enormously successful in simulating the transport of electrons, for example, in radiotherapy. MC-derived values of the water-to-air stopping-power ratio, s(w/air), are used in all modern codes of practice for absolute dose determination in radiotherapy clinics. MC can also directly yield the dose ratio Dmed/Ddet for a dosimeter in a medium, and Correlated Sampling has been exploited to increase the efficiency, e. g., the central electrode in an ion chamber (aluminium vs. graphite). The extremely low density of the gas in an ion chamber poses problems for CH codes. However, multiple scattering can now be combined with single scattering and is expected to finally resolve important chamber perturbation effects. An exciting application of CH MC in radiotherapy is the computation of dose distributions in patients. Currently one can achieve an uncertainty around 1% (1 SD) in mm-sized voxels in several minutes for an electron beam and in around an hour for a photon treatment plan on hardware costing less than $20,000, and thus avoid all the various approximations conventionally used to account for inhomogeneities. In the microdosimetry/track structure field, CH codes have shown that the fluence (dPhi/dE) per unit dose at low electron energies is virtually independent of incident particle energy or depth, which simply explains the negligible RBE variation.

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Energy deposition in small cylindrical targets by ultrasoft X-rays

Cited by 86 publications

References 23 publications

Quantitative modelling of DNA damage using Monte Carlo track structure method

Quantitative modelling of DNA damage using Monte Carlo track structure method

PDB4DNA: Implementation of DNA geometry from the Protein Data Bank (PDB) description for Geant4-DNA Monte-Carlo simulations

Condensed-history Monte-Carlo simulation for charged particles: what can it do for us?

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