oalib

Publish in OALib Journal

ISSN: 2333-9721

APC: Only $99

Submit

Any time

2019 ( 17 )

2018 ( 10 )

2017 ( 14 )

2016 ( 18 )

Custom range...

Search Results: 1 - 10 of 5746 matches for " Igor Pshenichnov "
All listed articles are free for downloading (OA Articles)
Page 1 /5746
Display every page Item
MCHIT - Monte Carlo model for proton and heavy-ion therapy
Igor Pshenichnov,Igor Mishustin,Walter Greiner
Physics , 2007, DOI: 10.1051/ndata:07214
Abstract: We study the propagation of nucleons and nuclei in tissue-like media within a Monte Carlo Model for Heavy-ion Therapy (MCHIT) based on the GEANT4 toolkit (version 8.2). The model takes into account fragmentation of projectile nuclei and secondary interactions of produced nuclear fragments. Model predictions are validated with available experimental data obtained for water and PMMA phantoms irradiated by monoenergetic carbon-ion beams. The MCHIT model describes well (1) the depth-dose distributions in water and PMMA, (2) the doses measured for fragments of certain charge, (3) the distributions of positron emitting nuclear fragments produced by carbon-ion beams, and (4) the energy spectra of secondary neutrons measured at different angles to the beam direction. Radial dose profiles for primary nuclei and for different projectile fragments are calculated and discussed as possible input for evaluation of biological dose distributions. It is shown that at the periphery of the transverse dose profile close to the Bragg peak the dose from secondary nuclear fragments is comparable to the dose from primary nuclei.
Neutrons from fragmentation of light nuclei in tissue-like media: a study with GEANT4 toolkit
Igor Pshenichnov,Igor Mishustin,Walter Greiner
Physics , 2005, DOI: 10.1088/0031-9155/50/23/005
Abstract: We study energy deposition by light nuclei in tissue-like media taking into account nuclear fragmentation reactions, in particular, production of secondary neutrons. The calculations are carried out within a Monte Carlo model for Heavy-Ion Therapy (MCHIT) based on the GEANT4 toolkit. Experimental data on depth-dose distributions for 135A-400A MeV C-12 and O-18 beams are described very well without any adjustment of the model parameters. This gives confidence in successful use of the GEANT4 toolkit for MC simulations of cancer therapy with beams of light nuclei. The energy deposition due to secondary neutrons produced by C-12 and Ne-20 beams in a (40-50 cm)^3 water phantom is estimated to 1-2% of the total dose, that is only slightly above the neutron contribution (~1%) induced by a 200 MeV proton beam.
Comparative study of depth-dose distributions for beams of light and heavy nuclei in tissue-like media
Igor Pshenichnov,Igor Mishustin,Walter Greiner
Physics , 2007, DOI: 10.1016/j.nimb.2008.02.025
Abstract: We study the energy deposition by light and heavy nuclei in tissue-like media as used for cancer therapy. The depth-dose distributions for protons, $^{3}$He, $^{12}$C, $^{20}$Ne, and $^{58}$Ni nuclei are calculated within a Monte Carlo model based on the GEANT4 toolkit. These distributions are compared with each other and with available experimental data. It is demonstrated that nuclear fragmentation reactions essentially reduce the peak-to-plateau ratio of the dose profiles for deeply penetrating energetic ions heavier than $^{3}$He. On the other hand, all projectiles up to $^{20}$Ne were found equally suitable for therapeutic use at low penetration depths.
Distributions of positron-emitting nuclei in proton and carbon-ion therapy studied with GEANT4
Igor Pshenichnov,Igor Mishustin,Walter Greiner
Physics , 2006, DOI: 10.1088/0031-9155/51/23/011
Abstract: Depth distributions of positron-emitting nuclei in PMMA phantoms are calculated within a Monte Carlo model for Heavy-Ion Therapy (MCHIT) based on the GEANT4 toolkit (version 8.0). The calculated total production rates of $^{11}$C, $^{10}$C and $^{15}$O nuclei are compared with experimental data and with corresponding results of the FLUKA and POSGEN codes. The distributions of e$^+$ annihilation points are obtained by simulating radioactive decay of unstable nuclei and transporting positrons in surrounding medium. A finite spatial resolution of the Positron Emission Tomography (PET) is taken into account in a simplified way. Depth distributions of $\beta^+$-activity as seen by a PET scanner are calculated and compared to available data for PMMA phantoms. The calculated $\beta^+$-activity profiles are in good agreement with PET data for proton and $^{12}$C beams at energies suitable for particle therapy. The MCHIT capability to predict the $\beta^+$-activity and dose distributions in tissue-like materials of different chemical composition is demonstrated.
Modeling spallation reactions in tungsten and uranium targets with the Geant4 toolkit*
Malyshkin Yury,Pshenichnov Igor,Mishustin Igor,Greiner Walter
EPJ Web of Conferences , 2012, DOI: 10.1051/epjconf/20122110006
Abstract: We study primary and secondary reactions induced by 600 MeV proton beams in monolithic cylindrical targets made of natural tungsten and uranium by using Monte Carlo simulations with the Geant4 toolkit [1–3]. Bertini intranuclear cascade model, Binary cascade model and IntraNuclear Cascade Liège (INCL) with ABLA model [4] were used as calculational options to describe nuclear reactions. Fission cross sections, neutron multiplicity and mass distributions of fragments for 238U fission induced by 25.6 and 62.9 MeV protons are calculated and compared to recent experimental data [5]. Time distributions of neutron leakage from the targets and heat depositions are calculated.
Nuclear fragmentation reactions in extended media studied with Geant4 toolkit
Igor Pshenichnov,Alexander Botvina,Igor Mishustin,Walter Greiner
Physics , 2009, DOI: 10.1016/j.nimb.2009.12.023
Abstract: It is well known from numerous experiments that nuclear multifragmentation is a dominating mechanism for production of intermediate-mass fragments in nucleus-nucleus collisions at energies above 100 A MeV. In this paper we investigate the validity and performance of the Fermi break-up model and the statistical multifragmentation model implemented as parts of the Geant4 toolkit. We study the impact of violent nuclear disintegration reactions on the depth-dose profiles and yields of secondary fragments for beams of light and medium-weight nuclei propagating in extended media. Implications for ion-beam cancer therapy and shielding from cosmic radiation are discussed.
PET monitoring of cancer therapy with He-3 and C-12 beams: a study with the GEANT4 toolkit
Igor Pshenichnov,Alexei Larionov,Igor Mishustin,Walter Greiner
Physics , 2007, DOI: 10.1088/0031-9155/52/24/007
Abstract: We study the spatial distributions of $\beta^+$-activity produced by therapeutic beams of $^3$He and $^{12}$C ions in various tissue-like materials. The calculations were performed within a Monte Carlo model for Heavy-Ion Therapy (MCHIT) based on the GEANT4 toolkit. The contributions from $^{10,11}$C, $^{13}$N, $^{14,15}$O, $^{17,18}$F and $^{30}$P positron-emitting nuclei were calculated and compared with experimental data obtained during and after irradiation. Positron emitting nuclei are created by $^{12}$C beam in fragmentation reactions of projectile and target nuclei. This leads to a $\beta^+$-activity profile characterised by a noticeable peak located close to the Bragg peak in the corresponding depth-dose distribution. On the contrary, as the most of positron-emitting nuclei are produced by $^3$He beam in target fragmentation reactions, the calculated total $\beta^+$-activity during or soon after the irradiation period is evenly distributed within the projectile range. However, we predict also the presence of $^{13}$N, $^{14}$O, $^{17,18}$F created in charge-transfer reactions by low-energy $^3$He ions close to the end of their range in several tissue-like media. The time evolution of $\beta^+$-activity profiles was investigated for both kinds of beams. Due to the production of $^{18}$F nuclide the $\beta^+$-activity profile measured 2 or 3 hours after irradiation with $^{3}$He ions will have a distinct peak correlated with the maximum of depth-dose distribution. We found certain advantages of low-energy $^{3}$He beams over low-energy proton beams for reliable PET monitoring during particle therapy of shallow located tumours. In this case the distal edge of $\beta^+$-activity distribution from $^{17}$F nuclei clearly marks the range of $^{3}$He in tissues.
Synthesis of neutron-rich transuranic nuclei in fissile spallation targets
Igor Mishustin,Yury Malyshkin,Igor Pshenichnov,Walter Greiner
Physics , 2014, DOI: 10.1016/j.nimb.2015.02.051
Abstract: A possibility of synthesizing neutron-reach super-heavy elements in spallation targets of Accelerator Driven Systems (ADS) is considered. A dedicated software called Nuclide Composition Dynamics (NuCoD) was developed to model the evolution of isotope composition in the targets during a long-time irradiation by intense proton and deuteron beams. Simulation results show that transuranic elements up to Bk-249 can be produced in multiple neutron capture reactions in macroscopic quantities. However, the neutron flux achievable in a spallation target is still insufficient to overcome the so-called fermium gap. Further optimization of the target design, in particular, by including moderating material and covering it by a reflector will turn ADS into an alternative source of transuranic elements in addition to nuclear fission reactors.
Comparative study of RBE and cell survival fractions for $^{1}$H, $^{4}$He, $^{12}$C and $^{16}$O beams using Geant4 and Microdosimetric Kinetic model
Lucas Burigo,Igor Pshenichnov,Igor Mishustin,Marcus Bleicher
Physics , 2014, DOI: 10.1088/0031-9155/60/8/3313
Abstract: Beams of $^{4}$He and $^{16}$O nuclei are considered for ion-beam cancer therapy as alternative options to protons and $^{12}$C nuclei. Spread-out Bragg peak (SOBP) distributions of physical dose and relative biological effectiveness for 10% survival are calculated by means of our Geant4-based Monte Carlo model for Heavy Ion Therapy (MCHIT) and the modified microdosimetric kinetic model. The depth distributions of cell survival fractions are calculated for $^{1}$H, $^{4}$He, $^{12}$C and $^{16}$O for tissues with normal (HSG cells), low and high radiosensitivity. In each case the cell survival fractions were compared separately for the target volume, behind and in front of it. In the case of normal radiosensitivity $^{4}$He and $^{12}$C better spare tissues in the entrance channel compared to protons and $^{16}$O. The cell survival fractions calculated, respectively, for the entrance channel and target volume are similar for $^{4}$He and $^{12}$C. When it is important to spare healthy tissues located after the distal edge of the SOBP plateau, $^{4}$He can be recommended due to reduced nuclear fragmentation of these projectiles. No definite advantages of $^{16}$O with respect to $^{12}$C were found, with the except of an enhanced impact of these heavier projectiles on radioresistant tumors.
Microdosimetry of radiation field from therapeutic C-12 beam in water: a study with Geant4 toolkit
Lucas Burigo,Igor Pshenichnov,Igor Mishustin,Marcus Bleicher
Physics , 2012, DOI: 10.1016/j.nimb.2013.05.021
Abstract: We model the responses of Tissue-Equivalent Proportional Counters (TEPC) to radiation fields of therapeutic C-12 beams in a water phantom and to quasi-monoenergetic neutrons in a PMMA phantom. Simulations are performed with the Monte Carlo model for Heavy Ion Therapy (MCHIT) based on the Geant4 toolkit. The shapes of the calculated lineal energy spectra agree well with measurements in both cases. The influence of fragmentation reactions on the TEPC response to a narrow pencil-like beam with its width smaller than the TEPC diameter is investigated by Monte Carlo modeling. It is found that total lineal energy spectra are not very sensitive to the choice of the nuclear fragmentation model used. The calculated frequency-mean lineal energy y_f differs from the data on the axis of a therapeutic beam by less than 10% and by 10-20% at other TEPC positions. The validation of MCHIT with neutron beams gives us confidence in estimating the contributions to lineal energy spectra due to secondary neutrons produced in water by C-12 nuclei. As found, the neutron contribution at 10 cm distance from the beam axis amounts to ~ 50% close the entrance to the phantom and decreases to ~ 25% at the depth of the Bragg peak and beyond it. The presented results can help in evaluating biological out-of-field doses in carbon-ion therapy.
Page 1 /5746
Display every page Item


Home
Copyright © 2008-2017 Open Access Library. All rights reserved.