Highlights • A review of the current status of Geant4-DNA is presented. • New physical models describing the interactions of electrons in water are described. • Physicochemical and chemical stages of ...water radiolysis can be simulated. • Several approaches are available for modeling geometries of biological targets. • Dedicated examples are proposed to demonstrate such capabilities.
Purpose:
TheGEANT4 general-purpose Monte Carlo simulation toolkit is able to simulate physical interaction processes of electrons, hydrogen and helium atoms with charge states (
H
0
,
H
+
) and (
He
...0
,
He
+
,
He
2
+
), respectively, in liquid water, the main component of biological systems, down to the electron volt regime and the submicrometer scale, providing GEANT4 users with the so-called “GEANT4-DNA” physics models suitable for microdosimetry simulation applications. The corresponding software has been recently re-engineered in order to provide GEANT4 users with a coherent and unique approach to the simulation of electromagnetic interactions within the GEANT4 toolkit framework (since GEANT4 version 9.3 beta). This work presents a quantitative comparison of these physics models with a collection of experimental data in water collected from the literature.
Methods:
An evaluation of the closeness between the total and differential cross section models available in theGEANT4 toolkit for microdosimetry and experimental reference data is performed using a dedicated statistical toolkit that includes the Kolmogorov–Smirnov statistical test. The authors used experimental data acquired in water vapor as direct measurements in the liquid phase are not yet available in the literature. Comparisons with several recommendations are also presented.
Results:
The authors have assessed the compatibility of experimental data withGEANT4 microdosimetry models by means of quantitative methods. The results show that microdosimetric measurements in liquid water are necessary to assess quantitatively the validity of the software implementation for the liquid water phase. Nevertheless, a comparison with existing experimental data in water vapor provides a qualitative appreciation of the plausibility of the simulation models. The existing reference data themselves should undergo a critical interpretation and selection, as some of the series exhibit significant deviations from each other.
Conclusions:
TheGEANT4-DNA physics models available in the GEANT4 toolkit have been compared in this article to available experimental data in the water vapor phase as well as to several published recommendations on the mass stopping power. These models represent a first step in the extension of the GEANT4 Monte Carlo toolkit to the simulation of biological effects of ionizing radiation.
Gold nanoparticles have been reported as a possible radio-sensitizer agent in radiation therapy due to their ability to increase energy deposition and subsequent direct damage to cells and DNA within ...their local vicinity. Moreover, this increase in energy deposition also results in an increase of the radiochemical yields. In this work we present, for the first time, an in silico investigation, based on the general purpose Monte Carlo simulation toolkit Geant4, into energy deposition and radical species production around a spherical gold nanoparticle 50nm in diameter via proton irradiation. Simulations were preformed for incident proton energies ranging from 2 to 170MeV, which are of interest for clinical proton therapy.
The first green biorefinery of larch wood based on the fractionation of biomass into dihydroquercetin (DHQ), arabinogalactan (AG), microcrystalline cellulose (MCC) and soluble lignin (SL) is ...reported. The new green method of one-step isolation of DHQ and AG from larch wood by ethanol–water solution was developed. The first results of kinetic studies and optimization of the process of extracted larch wood peroxide fractionation into MCC and SL in acetic acid–water medium in the presence of green TiO
2
catalyst are described. The products obtained from larch wood were characterized by FTIR, NMR, XRD, AFM and chemical methods. The scheme of larch wood biorefinery is suggested which integrates the developed processes of woody biomass fractionation into DHQ, AG, MCC and SL. All developed methods use non-toxic and less-toxic reagents, such as water, ethanol, hydrogen peroxide and acetic acid.
Cancer treatment with energetic carbon ions has distinct advantages over proton or photon irradiation. In this paper we present a simulation model integrated into the Geant4 Monte Carlo toolkit ...(version 9.3) which enables the use of ICRU 73 stopping powers for ion transport calculations. For a few materials, revised ICRU 73 stopping power tables recently published by ICRU (P. Sigmund, A. Schinner, H. Paul, Errata and Addenda: ICRU Report 73 (Stopping of Ions Heavier than Helium), International Commission on Radiation Units and Measurements, 2009) were incorporated into Geant4, also covering media like water which are of importance in radiotherapeutical applications. We examine, with particular attention paid to the recent developments, the accuracy of current Geant4 models for simulating Bragg peak profiles of
12C ions incident on water and polyethylene targets. Simulated dose distributions are validated against experimental data available in the literature, where the focus is on beam energies relevant to ion therapy applications (90–400
MeV/u). A quantitative analysis is performed which addresses the precision of the Bragg peak position and proportional features of the dose distribution. It is shown that experimental peak positions can be reproduced within 0.2% of the particle range in the case of water, and within 0.9% in the case of polyethylene. The comparisons also demonstrate that the simulations accurately render the full width at half maximum (FWHM) of the measured Bragg peaks in water. For polyethylene slight deviations from experimental peak widths are partly attributed to systematic effects due to a simplified geometry model adopted in the simulation setup.
Results of the study on green valorization of hardwood biomass into valuable chemicals with the use of solid catalysts were described. The heterogeneous catalytic processes of hemicelluloses and ...cellulose hydrolysis, wood oxidative fractionation and lignin depolymerization in supercritical spirits are suggested to employ for the green biorefinery of hardwood to xylose, pure cellulose, glucose, alcohols and liquid hydrocarbons.
The structure, principle of operation, and metrological performance of the rubidium atomic fountain developed at VNIIFTRI are presented. The aim of the present work is to assess the preliminary ...uncertainty budget of this standard. The physical effects that cause the largest shifts of the measured frequency, namely, the quadratic Zeeman effect, blackbody radiation effect, gravitational redshift, and cavity pulling effect are considered. The frequency stability of the rubidium fountain is given by σ
y
(τ) = 1.43·10
–13
τ
–1/2
at an evaluated frequency uncertainty of less than 2·10
–16
. Such performances are at the level of the best rubidium fountain standards developed worldwide. These results are relevant for the time and frequency metrology and for timescales.
The Geant4 Simulation Toolkit provides an ample set of physics models describing electromagnetic interactions of particles with matter. This paper presents the results of a series of comparisons for ...the evaluation of Geant4 electromagnetic processes with respect to United States National Institute of Standards and Technologies (NIST) reference data. A statistical analysis was performed to estimate quantitatively the compatibility of Geant4 electromagnetic models with NIST data; the statistical analysis also highlighted the respective strengths of the different Geant4 models.
The Binary Cascade Folger, G.; Ivanchenko, V. N.; Wellisch, J. P.
The European physical journal. A, Hadrons and nuclei,
09/2004, Letnik:
21, Številka:
3
Journal Article
Recent progress in development of single and multiple scattering models within the Geant4 toolkit is presented. Different options available to users are discussed. The comparisons with the data are ...shown. The trade of precision versus CPU performance is discussed with the focus on LHC detectors simulation.
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