Monte Carlo simulation of energy-deposit clustering for ions of the same LET in liquid water

This work presents a Monte Carlo study of energy depositions due to protons, alpha particles and carbon ions of the same linear-energy-transfer (LET) in liquid water. The corresponding track structures were generated using the Geant4-DNA toolkit, and the energy deposition spatial distributions were analyzed using an adapted version of the DBSCAN clustering algorithm. Combining the Geant4 simulations and the clustering algorithm it was possible to compare the quality of the different radiation types. The ratios of clustered and single energy depositions are shown versus particle LET and frequencymean lineal energies. The estimated effect of these types of radiation on biological tissues is then discussed by comparing the results obtained for different particles with the same LET

Monte Carlo simulation of energy-deposit clustering for ions of the same LET in liquid water

This work presents a Monte Carlo study of energy depositions due to protons, alpha particles and carbon ions of the same linear-energy-transfer (LET) in liquid water. The corresponding track structures were generated using the Geant4-DNA toolkit, and the energy deposition spatial distributions were analyzed using an adapted version of the DBSCAN clustering algorithm. Combining the Geant4 simulations and the clustering algorithm it was possible to compare the quality of the different radiation types. The ratios of clustered and single energy depositions are shown versus particle LET and frequency-mean lineal energies. The estimated effect of these types of radiation on biological tissues is then discussed by comparing the results obtained for different particles with the same LET.571209224Open University in Milton Keynes in the UKFrench CNRS [PICS 5873]Saint Joseph University in Beirut (Lebanon) [PICS 5873]French Agence Nationale de la Recherche [ANR-09-BLAN-0135-01]European Space Agency [AO6041-22712/09/NL/AT]FAEPEX foundation at UNICAMP, BrazilFrench CNRS [PICS 5873]Saint Joseph University in Beirut (Lebanon) [PICS 5873]French Agence Nationale de la Recherche [ANR-09-BLAN-0135-01]European Space Agency [AO6041-22712/09/NL/AT

Proton transport in water and DNA components: A Geant4 Monte Carlo simulation

Accurate modeling of DNA damages resulting from ionizing radiation remains a challenge of today's radiobiology research. An original set of physics processes has been recently developed for modeling the detailed transport of protons and neutral hydrogen atoms in liquid water and in DNA nucleobases using the Geant4-DNA extension of the open source Geant4 Monte Carlo simulation toolkit. The theoretical cross sections as well as the mean energy transfers during the different ionizing processes were taken from recent works based on classical as well as quantum mechanical predictions. Furthermore, in order to compare energy deposition patterns in liquid water and DNA material, we here propose a simplified cellular nucleus model made of spherical voxels, each containing randomly oriented nanometer-size cylindrical targets filled with either liquid water or DNA material (DNA nucleobases) both with a density of 1 g/cm3. These cylindrical volumes have dimensions comparable to genetic material units of mammalian cells, namely, 25 nm (diameter) 25 nm (height) for chromatin fiber segments, 10 nm (d) 5 nm (h) for nucleosomes and 2 nm (d) 2 nm (h) for DNA segments. Frequencies of energy deposition in the cylindrical targets are presented and discusse

Combination of electromagnetic physics processes for microdosimetry in liquid water with the Geant4 Monte Carlo simulation toolkit

The Geant4 Monte Carlo simulation toolkit provides a set of electromagnetic physics processes adapted to the detailed simulation of particle interactions in liquid water for microdosimetry applications, such as single-cell irradiation with light ion beams. These processes, developed within the framework of the Geant4-DNA project, adopt a software design allowing their combination with other electromagnetic physics processes available in the Geant4 toolkit. This work describes the combination of Geant4-DNA electron processes with Geant4 photon processes

Modeling proton and alpha elastic scattering in liquid water In Geant4-DNA

FAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULOElastic scattering of protons and alpha (a) particles by water molecules cannot be neglected at low incident energies. However, this physical process is currently not available in the "Geant4-DNA" extension of the Geant4 Monte Carlo simulation toolkit. In this work, we report on theoretical differential and integral cross sections of the elastic scattering process for 100 eV-1 MeV incident protons and for 100 eV-10 MeV incident a particles in liquid water. The calculations are performed within the classical framework described by Everhart et al., Ziegler et al. and by the ICRU 49 Report. Then, we propose an implementation of the corresponding classes into the Geant4-DNA toolkit for modeling the elastic scattering of protons and a particles. Stopping powers as well as ranges are also reported. Then, it clearly appears that the account of the elastic scattering process in the slowing-down of the charged particle improves the agreement with the existing data in particular with the ICRU recommendations.Elastic scattering of protons and alpha (a) particles by water molecules cannot be neglected at low incident energies. However, this physical process is currently not available in the "Geant4-DNA" extension of the Geant4 Monte Carlo simulation toolkit. In this work, we report on theoretical differential and integral cross sections of the elastic scattering process for 100 eV-1 MeV incident protons and for 100 eV-10 MeV incident a particles in liquid water. The calculations are performed within the classical framework described by Everhart et al., Ziegler et al. and by the ICRU 49 Report. Then, we propose an implementation of the corresponding classes into the Geant4-DNA toolkit for modeling the elastic scattering of protons and a particles. Stopping powers as well as ranges are also reported. Then, it clearly appears that the account of the elastic scattering process in the slowing-down of the charged particle improves the agreement with the existing data in particular with the ICRU recommendations.343132137FAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULOFAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO2011/51594-2Agências de fomento estrangeiras apoiaram essa pesquisa, mais informações acesse artig

Performance of a new atomistic geometrical model of the B-DNA configuration for DNA-radiation interaction simulations

We have recently developed an atomistic model of the B-DNA configuration, up to the 30-nm chromatin fiber. This model is intended to be used in Monte Carlo simulations of the DNA-radiation interaction, specifically in conjunction with the Geant4-DNA extension of the Geant4 Monte Carlo toolkit. In this work, 11449 parallel chromatin fibers have been arranged within a cube mimicking a cell nucleus containing about 6.5×109 base pairs. Each atom in the model is represented by a sphere with the corresponding van der Waals radius. Direct single, double and total DNA strand break yields due to the impact of protons and alpha particles with LET ranging from 4.57 to 207.1 keV/μm have been determined. Also, the corresponding site-hit probabilities have been calculated

Carbon Ion Fragmentation Effects On The Nanometric Level Behind The Bragg Peak Depth

In this study, fragmentation yields of carbon therapy beams are estimated using the Geant4 simulation toolkit version 9.5. Simulations are carried out in a step-by-step mode using the Geant4-DNA processes for each of the major contributing fragments. The energy of the initial beam is taken 400 MeV amu-1 as this is the highest energy, which is used for medical accelerators and this would show the integral role of secondary contributions in radiotherapy irradiations. The obtained results showed that 64% of the global dose deposition is initiated by carbon ions, while up to 36% is initiated by the produced fragments including all their isotopes. The energy deposition clustering yields of each of the simulated fragments are then estimated using the DBSCAN clustering algorithm and they are compared to the yields of the incident primary beam.592476917702Agostinelli, S., Geant4 - A simulation toolkit (2003) Nucl. Instrum. Methods Phys. Res., 506, pp. 250-303Allison, J., Geant4 developments and applications (2006) IEEE Trans. Nucl. Sci., 53, pp. 270-278Bohlen, T., Cerutti, F., Dosanjh, M., Ferrari, A., Gudowska, I., Mairani, A., Quesada, J.M., Benchmarking nuclear models of FLUKA and GEANT4 for carbon ion therapy (2010) Phys. Med. Biol., 55 (19), pp. 5833-5847Endo, S., Takada, M., Onizuka, Y., Tanaka, K., Maeda, N., Ishikawa, M., Miyahara, N., Hoshi, M., Microdosimetric evaluation of secondary particles in a phantom produced by carbon 290 MeV/nucleon ions at HIMAC (2007) J. Radiat. Res. (Tokyo), 48, pp. 397-406Francis, Z., Incerti, S., Ivanchenko, V., Champion, C., Karamitros, M., Bernal, M.A., El Bitar, Z., Monte Carlo simulation of energy-deposit clustering for ions of the same LET in liquid water (2012) Phys. Med. Biol., 57 (1), pp. 209-224Francis, Z., Villagrasa, C., Clairand, I., Simulation of DNA damage clustering after proton irradiation using an adapted DBSCAN algorithm (2011) Comput. Methods Programs Biomed., 101, pp. 265-270Friedland, W., Dingfelder, M., Kundrat, P., Jacob, P., Track structures, DNA targets and radiation effects in the biophysical Monte Carlo simulation code PARTRAC (2011) Mutat. Res., 711, pp. 28-40Gudowska, I., Sobolevsky, N., Andreo, P., Belkic, D., Brahme, A., Ion beam transport in tissue-like media using the Monte Carlo code SHIELD-HIT (2004) Phys. Med. Biol., 49 (10), pp. 1933-1958Haettner, E., (2006) ThesisHaettner, E., Iwase, H., Kramer, M., Kraft, G., Schardt, D., Experimental study of nuclear fragmentation of 200 and 400 MeV/u 12C ions in water for applications in particle therapy (2013) Phys. Med. Biol., 58 (23), pp. 8265-8279Haettner, E., Iwase, H., Schardt, D., Experimental fragmentation studies with 12C therapy beams (2006) Radiat. Prot. Dosim., 122, pp. 485-487Hollmark, M., Gudowska, I., Belkic, D., Brahme, A., Sobolevsky, N., An analytical model for light ion pencil beam dose distributions: Multiple scattering of primary and secondary ions (2008) Phys. Med. Biol., 53 (13), pp. 3477-3491Hollmark, M., Uhrdin, J., Belkic, D., Gudowska, I., Brahme, A., Influence of multiple scattering and energy loss straggling on the absorbed dose distributions of therapeutic light ion beams: I. Analytical pencil beam model (2004) Phys. Med. Biol., 49 (14), pp. 3247-3265Hultqvist, M., Lazzeroni, M., Botvina, A., Gudowska, I., Sobolevsky, N., Brahme, A., Evaluation of nuclear reaction cross-sections and fragment yields in carbon beams using the SHIELD-HIT Monte Carlo code. Comparison with experiments (2012) Phys. Med. Biol., 57 (13), pp. 4369-4385Hunniford, C.A., Timson, D.J., Davies, R.J.H., McCullough, R.W., Damage to plasmid DNA induced by low energy carbon ions (2007) Phys. Med. 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Geant4 electromagnetic physics: improving simulation performance and accuracy

The most recent upgrades of the electromagnetic (EM) physics "standard" and "low energy" sub-libraries of the general purpose Geant4 Monte Carlo simulation toolkit are described. These upgrades are relevant to different application domains including high energy physics, medical physics and space science. Validation results are presented and discussed

Geant4 electromagnetic physics: improving simulation performance and accuracy

The most recent upgrades of the electromagnetic (EM) physics "standard" and "low energy" sub-libraries of the general purpose Geant4 Monte Carlo simulation toolkit are described. These upgrades are relevant to different application domains including high energy physics, medical physics and space science. Validation results are presented and discussed

Modeling Radiation Chemistry and Biology in the Geant4 Toolkit

International audienceSimulation of biological effects of ionizing radiation at the DNA scale requires not only the modeling of direct damages induced on DNA by the incident radiation and by secondary particles but also the modeling of indirect effects of radiolytic products resulting from water radiolysis. They can provoke single and double strand breaks by reacting with DNA. The Geant4 Monte Carlo toolkit is currently being extended for the simulation of biological damages of ionizing radiation at the DNA scale in the framework of the "Geant4-DNA" project. Physics models for the modeling of direct effects are already available in Geant4. In the present paper, an approach for the modeling of radiation chemistry in pure liquid water within Geant4 is presented. In particular, this modeling includes Brownian motion and chemical reactions between molecules following water radiolysis. First results on time-dependent radiochemical yields1 from 1 picosecond up to 1 microsecond after irradiation are compared to published data and discussed