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M.U. Bug

Other affiliations: University of Wollongong
Bio: M.U. Bug is an academic researcher from German National Metrology Institute. The author has contributed to research in topics: Monte Carlo method & Ionization. The author has an hindex of 11, co-authored 33 publications receiving 430 citations. Previous affiliations of M.U. Bug include University of Wollongong.

Papers
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Journal ArticleDOI
TL;DR: A multiscale approach is needed to lay the foundation for the aforementioned new physical quantities relating track structure to relative biological effectiveness in proton and ion beam therapy and the European metrology project, Biologically Weighted Quantities in Radiotherapy, is introduced.
Abstract: Proton and ion beams are radiotherapy modalities of increasing importance and interest. Because of the different biological dose response of these radiations as compared with high-energy photon beams, the current approach of treatment prescription is based on the product of the absorbed dose to water and a biological weighting factor, but this is found to be insufficient for providing a generic method to quantify the biological outcome of radiation. It is therefore suggested to define new dosimetric quantities that allow a transparent separation of the physical processes from the biological ones. Given the complexity of the initiation and occurrence of biological processes on various time and length scales, and given that neither microdosimetry nor nanodosimetry on their own can fully describe the biological effects as a function of the distribution of energy deposition or ionization, a multiscale approach is needed to lay the foundation for the aforementioned new physical quantities relating track struct...

65 citations

Journal ArticleDOI
TL;DR: In this article, the experimental differential scattering cross sections of tetrahydrofuran for the elastic scattering of electrons were calculated in the energy range between 60 eV and 1 keV by applying the modified independent-atom model.
Abstract: Differential elastic scattering cross sections of tetrahydrofuran for electrons were measured absolutely in the energy range from 20 eV to 1 keV at scattering angles between 5\ifmmode^\circ\else\textdegree\fi{} and 135\ifmmode^\circ\else\textdegree\fi{}. The measurements were carried out using a crossed-beam arrangement without the application of the widely used relative flow technique. The experimental differential scattering cross sections could be put on an absolute scale by means of the total electron scattering cross sections of tetrahydrofuran and of the current loss of the primary electron beam in the forward direction arising due to the scattering by the molecular beam. The total scattering cross sections were determined for electron energies between 6 eV and 1 keV using a separate linear transmission experiment. The differential cross sections of tetrahydrofuran for the elastic scattering of electrons were also calculated in the energy range between 60 eV and 1 keV by applying the modified independent-atom model. A comparison with the experimental results showed a satisfactory agreement, indicating that the selected theoretical model is adequate for these calculations.

58 citations

Journal ArticleDOI
TL;DR: The Geant4-DNA toolkit as mentioned in this paper provides the first cross section data set of DNA constituents for an impact of electrons in the energy range between about 10 eV and 1 eV on a DNA target.

56 citations

Journal ArticleDOI
TL;DR: In this article, a comparison of the two codes was made for incident electrons of energy in the range between 50 eV and 10 keV, for protons of energy between 300 keV and10 MeV, and for alpha particles of energy 1 and 10 MeV as these were the energy ranges available in both codes at the time this investigation was carried out.
Abstract: The concept of nanodosimetry is based on the assumption that initial damage to cells is related to the number of ionizations (the ionization cluster size) directly produced by single particles within, or in the close vicinity of, short segments of DNA. The ionization cluster-size distribution and other nanodosimetric quantities, however, are not directly measurable in biological targets and our current knowledge is mostly based on numerical simulations of particle tracks in water, calculating track structure parameters for nanometric target volumes. The assessment of nanodosimetric quantities derived from particle-track calculations using different Monte Carlo codes plays, therefore, an important role for a more accurate evaluation of the initial damage to cells and, as a consequence, of the biological effectiveness of ionizing radiation. The aim of this work is to assess the differences in the calculated nanodosimetric quantities obtained with Geant4-DNA as compared to those of the ad hoc particle-track Monte Carlo code 'PTra' developed at Physikalisch-Technische Bundesanstalt (PTB), Germany. The comparison of the two codes was made for incident electrons of energy in the range between 50 eV and 10 keV, for protons of energy between 300 keV and 10 MeV, and for alpha particles of energy between 1 and 10 MeV as these were the energy ranges available in both codes at the time this investigation was carried out. Good agreement was found for nanodosimetric characteristics of track structure calculated in the high-energy range of each particle type. For lower energies, significant differences were observed, most notably in the estimates of the biological effectiveness. The largest relative differences obtained were over 50%; however, generally the order of magnitude was between 10% and 20%.

36 citations

Journal ArticleDOI
TL;DR: In this paper, the effects of a magnetic field on the pattern of ionizations at nanometric level by means of Monte Carlo simulations using the Geant4-DNA toolkit were investigated.
Abstract: The increasing use of MRI-guided radiation therapy evokes the necessity to investigate the potential impact of a magnetic field on the biological effectiveness of therapeutic radiation beams. While it is known that a magnetic field, applied during irradiation, can improve the macroscopic absorbed dose distribution of electrons in the tumor region, effects on the microscopic distribution of energy depositions and ionizations have not yet been investigated. An effect on the number of ionizations in a DNA segment, which is related to initial DNA damage in form of complex strand breaks, could be beneficial in radiation therapy. In this work we studied the effects of a magnetic field on the pattern of ionizations at nanometric level by means of Monte Carlo simulations using the Geant4-DNA toolkit. The track structure of low-energy electrons in the presence of a uniform static magnetic field of strength up to 14 T was calculated for a simplified DNA segment model in form of a water cylinder. In the case that no magnetic field is applied, nanodosimetric results obtained with Geant4-DNA were compared with those from the PTB track structure code. The obtained results suggest that any potential enhancement of complexity of DNA strand breaks induced by irradiation in a magnetic field is not related to modifications of the low-energy secondary electrons track structure.

36 citations


Cited by
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Journal ArticleDOI
John Allison1, K. Amako2, John Apostolakis3, Pedro Arce4, Makoto Asai5, Tsukasa Aso6, Enrico Bagli, Alexander Bagulya7, Sw. Banerjee8, G. Barrand9, B. R. Beck10, Alexey Bogdanov11, D. Brandt, Jeremy M. C. Brown12, Helmut Burkhardt3, Ph Canal8, D. Cano-Ott4, Stephane Chauvie, Kyung-Suk Cho13, G.A.P. Cirrone14, Gene Cooperman15, M. A. Cortés-Giraldo16, G. Cosmo3, Giacomo Cuttone14, G.O. Depaola17, Laurent Desorgher, X. Dong15, Andrea Dotti5, Victor Daniel Elvira8, Gunter Folger3, Ziad Francis18, A. Galoyan19, L. Garnier9, M. Gayer3, K. Genser8, Vladimir Grichine7, Vladimir Grichine3, Susanna Guatelli20, Susanna Guatelli21, Paul Gueye22, P. Gumplinger23, Alexander Howard24, Ivana Hřivnáčová9, S. Hwang13, Sebastien Incerti25, Sebastien Incerti26, A. Ivanchenko3, Vladimir Ivanchenko3, F.W. Jones23, S. Y. Jun8, Pekka Kaitaniemi27, Nicolas A. Karakatsanis28, Nicolas A. Karakatsanis29, M. Karamitrosi30, M.H. Kelsey5, Akinori Kimura31, Tatsumi Koi5, Hisaya Kurashige32, A. Lechner3, S. B. Lee33, Francesco Longo34, M. Maire, Davide Mancusi, A. Mantero, E. Mendoza4, B. Morgan35, K. Murakami2, T. Nikitina3, Luciano Pandola14, P. Paprocki3, J Perl5, Ivan Petrović36, Maria Grazia Pia, W. Pokorski3, J. M. Quesada16, M. Raine, Maria A.M. Reis37, Alberto Ribon3, A. Ristic Fira36, Francesco Romano14, Giorgio Ivan Russo14, Giovanni Santin38, Takashi Sasaki2, D. Sawkey39, J. I. Shin33, Igor Strakovsky40, A. Taborda37, Satoshi Tanaka41, B. Tome, Toshiyuki Toshito, H.N. Tran42, Pete Truscott, L. Urbán, V. V. Uzhinsky19, Jerome Verbeke10, M. Verderi43, B. Wendt44, H. Wenzel8, D. H. Wright5, Douglas Wright10, T. Yamashita, J. Yarba8, H. Yoshida45 
TL;DR: Geant4 as discussed by the authors is a software toolkit for the simulation of the passage of particles through matter, which is used by a large number of experiments and projects in a variety of application domains, including high energy physics, astrophysics and space science, medical physics and radiation protection.
Abstract: Geant4 is a software toolkit for the simulation of the passage of particles through matter. It is used by a large number of experiments and projects in a variety of application domains, including high energy physics, astrophysics and space science, medical physics and radiation protection. Over the past several years, major changes have been made to the toolkit in order to accommodate the needs of these user communities, and to efficiently exploit the growth of computing power made available by advances in technology. The adaptation of Geant4 to multithreading, advances in physics, detector modeling and visualization, extensions to the toolkit, including biasing and reverse Monte Carlo, and tools for physics and release validation are discussed here.

2,260 citations

Journal ArticleDOI
TL;DR: This paper presents the most recent review of the Geant4-DNA extension, as available to Geant 4 users since June 2015 (release 10.2 Beta), and includes the description of new physical models for thedescription of electron elastic and inelastic interactions in liquid water, as well as new examples dedicated to the simulation of physicochemical and chemical stages of water radiolysis.

370 citations

Journal ArticleDOI
TL;DR: This Special Report presents a description of Geant4-DNA user applications dedicated to the simulation of track structures (TS) in liquid water and associated physical quantities (e.g., range, stopping power, mean free path…) and shows that the most recent sets of physics models available in Geant 4-DNA enable more accurate simulation of stopping powers, dose point kernels, and W-values in liquidWater.
Abstract: This Special Report presents a description of Geant4-DNA user applications dedicated to the simulation of track structures (TS) in liquid water and associated physical quantities (e.g., range, stopping power, mean free path…). These example applications are included in the Geant4 Monte Carlo toolkit and are available in open access. Each application is described and comparisons to recent international recommendations are shown (e.g., ICRU, MIRD), when available. The influence of physics models available in Geant4-DNA for the simulation of electron interactions in liquid water is discussed. Thanks to these applications, the authors show that the most recent sets of physics models available in Geant4-DNA (the so-called "option4" and "option 6" sets) enable more accurate simulation of stopping powers, dose point kernels, and W-values in liquid water, than the default set of models ("option 2") initially provided in Geant4-DNA. They also serve as reference applications for Geant4-DNA users interested in TS simulations.

244 citations

Journal ArticleDOI
TL;DR: The TOPAS-nBio extension to the TOPAS MC application offers access to accurate and detailed multiscale simulations, from a macroscopic description of the radiation field to microscopic description of biological outcome for selected cells.
Abstract: The TOPAS Monte Carlo (MC) system is used in radiation therapy and medical imaging research, having played a significant role in making Monte Carlo simulations widely available for proton therapy related research. While TOPAS provides detailed simulations of patient scale properties, the fundamental unit of the biological response to radiation is a cell. Thus, our goal was to develop TOPAS-nBio, an extension of TOPAS dedicated to advance understanding of radiobiological effects at the (sub-)cellular, (i.e., the cellular and sub-cellular) scale. TOPAS-nBio was designed as a set of open source classes that extends TOPAS to model radiobiological experiments. TOPAS-nBio is based on and extends Geant4-DNA, which extends the Geant4 toolkit, the basis of TOPAS, to include very low-energy interactions of particles down to vibrational energies, explicitly simulates every particle interaction (i.e., without using condensed histories) and propagates radiolysis products. To further facilitate the use of TOPAS-nBio, a graphical user interface was developed. TOPAS-nBio offers full track-structure Monte Carlo simulations, integration of chemical reactions within the first millisecond, an extensive catalogue of specialized cell geometries as well as sub-cellular structures such as DNA and mitochondria, and interfaces to mechanistic models of DNA repair kinetics. We compared TOPAS-nBio simulations to measured and published data of energy deposition patterns and chemical reaction rates (G values). Our simulations agreed well within the experimental uncertainties. Additionally, we expanded the chemical reactions and species provided in Geant4-DNA and developed a new method based on independent reaction times (IRT), including a total of 72 reactions classified into 6 types between neutral and charged species. Chemical stage simulations using IRT were a factor of 145 faster than with step-by-step tracking. Finally, we applied the geometric/chemical modeling to obtain initial yields of double-strand breaks (DSBs) in DNA fibers for proton irradiations of 3 and 50 MeV and compared the effect of including chemical reactions on the number and complexity of DSB induction. Over half of the DSBs were found to include chemical reactions with approximately 5% of DSBs caused only by chemical reactions. In conclusion, the TOPAS-nBio extension to the TOPAS MC application offers access to accurate and detailed multiscale simulations, from a macroscopic description of the radiation field to microscopic description of biological outcome for selected cells. TOPAS-nBio offers detailed physics and chemistry simulations of radiobiological experiments on cells simulating the initially induced damage and links to models of DNA repair kinetics.

110 citations

Journal ArticleDOI
TL;DR: In this paper, a multiscale approach to the assessment of biodamage resulting upon irradiation of biological media with ions is reviewed, explained and compared to other approaches, and a recipe for application of the multiscales approach is formulated.
Abstract: The multiscale approach to the assessment of biodamage resulting upon irradiation of biological media with ions is reviewed, explained and compared to other approaches. The processes of ion propagation in the medium concurrent with ionization and excitation of molecules, transport of secondary products, dynamics of the medium, and biological damage take place on a number of different temporal, spatial and energy scales. The multiscale approach, a physical phenomenon-based analysis of the scenario that leads to radiation damage, has been designed to consider all relevant effects on a variety of scales and develop an approach to the quantitative assessment of biological damage as a result of irradiation with ions. Presently, physical and chemical effects are included in the scenario while the biological effects such as DNA repair are only mentioned. This paper explains the scenario of radiation damage with ions, overviews its major parts, and applies the multiscale approach to different experimental conditions. On the basis of this experience, the recipe for application of the multiscale approach is formulated. The recipe leads to the calculation of relative biological effectiveness.

106 citations