| 1. |
- Grindborg, J.-E., et al.
(författare)
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Nanodosimetric measurements and calculations in a neutron therapy beam
- 2007
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Ingår i: Radiation Protection Dosimetry. - : Oxford University Press (OUP). - 0144-8420 .- 1742-3406. ; 126:1-4, s. 463-466
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Tidskriftsartikel (refereegranskat)abstract
- A comparison of calculated and measured values of the dose mean lineal energy (yD) for the former neutron therapy beam at Louvain-la-Neuve is reported. The measurements were made with wall-less tissue-equivalent proportional counters using the variance-covariance method and simulating spheres with diameters between 10 nm and 15 µm. The calculated yD-values were obtained from simulated energy distributions of neutrons and charged particles inside an A-150 phantom and from published yD-values for mono-energetic ions. The energy distributions of charged particles up to oxygen were determined with the SHIELD-HIT code using an MCNPX simulated neutron spectrum as an input. The mono-energetic ion yD-values in the range 3-100 nm were taken from track-structure simulations in water vapour done with PITS/KURBUC. The large influence on the dose mean lineal energy from the light ion (A > 4) absorbed dose fraction, may explain an observed difference between experiment and calculation. The latter being larger than earlier reported result. Below 50 nm, the experimental values increase while the calculated decrease. © The Author 2007. Published by Oxford University Press. All rights reserved.
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| 5. |
- Ersmark, T., et al.
(författare)
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Influence of geometry model approximations on Geant4 simulation results of the Columbus/ISS radiation environment
- 2007
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Ingår i: Radiation Measurements. - : Elsevier BV. - 1350-4487 .- 1879-0925. ; 42, s. 1342-1350
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Tidskriftsartikel (refereegranskat)abstract
- The influence of geometry model approximations on Geant4 Monte Carlo simulation results of the radiation environment on-board the Columbus module of the International Space Station (ISS) has been investigated. Three geometry models of Columbus with different levels of detail and a geometry model of ISS have been developed. These geometries have been used for Geant4 simulations of the radiation environment inside Columbus induced by trapped protons and Galactic Cosmic Ray protons. Simulated dose rates and particle spectra on-board Columbus for each of the three Columbus models, with or without the ISS geometry model included, are presented and compared. From comparisons of simulated dose rates and particle spectra for the three different geometry models it was found that the most detailed geometry model (750 volumes) produced results similar to a much less detailed model (23 volumes). The most detailed geometry model was concluded to be a sufficiently detailed approximation of the physical Columbus for the purpose of proton induced space radiation studies. The simulated dose rates are compatible with measurements on-board the ISS. The simulation results also show that an increase in shielding thickness decreases the simulated dose rate induced by trapped protons. For Galactic Cosmic Ray protons the dose rate remains unchanged or is slightly increased.
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| 6. |
- Ersmark, Tore, et al.
(författare)
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Status of the DESIRE project : Geant4 physics validation studies and first results from columbus/ISS radiation simulations
- 2004
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Ingår i: IEEE NUCLEAR SCIENCE SYMPOSIUM, CONFERENCE RECORD. ; , s. 1540-1544
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The DESIRE (Dose Estimation by Simulation of the ISS Radiation Environment) project aimes to accurately calculate radiation fluxes and doses to astronauts inside the European Columbus module of the International Space Station using Geant4. Firstly physics benchmark studies have been performed and comparisons made to experimental data and other particle transport programs. This will be followed by a detailed evaluation of the incident radiation fields on the ISS and culminate with the geometry modelling and full-scale flux and dose simulations for the Columbus. Geant4 validation studies are presented here. These concern the angle and energy distribution of particles leaving irradiated targets and of energy depositions in the targets. Comparisons are made between simulations using different Geant4 physics models, experimental data and other particle transport programs. Geant4 using the "Binary Cascade" model for inelastic nucleon reactions performs very well in these comparisons but some issues with other models remain to be resolved if these models are to be used for space radiation shielding applications. Results of Geant4 simulations of the transport of relevant radiation field components through the hull of the Columbus/ISS are also presented.
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| 7. |
- Ersmark, Tore, et al.
(författare)
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Status of the DESIRE project : Geant4 physics validation studies and first results from columbus/ISS radiation simulations
- 2004
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Ingår i: IEEE Transactions on Nuclear Science. - 0018-9499 .- 1558-1578. ; 51:4, s. 1378-1384
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Tidskriftsartikel (refereegranskat)abstract
- The Dose Estimation by Simulation of the ISS Radiation Environment (DESIRE) project aims to accurately calculate radiation fluxes and doses to astronauts inside the European Columbus module of the International Space Station using Geant4. Since Geant4 has not been previously used for this type of application it needs to be validated. This will be followed by a detailed evaluation of the incident radiation fields on ISS and culminate with the geometry modeling and full-scale flux and dose simulations for Columbus. Geant4 validation studies and comparisons to other tools are presented. These concern the angle and energy distributions of particles leaving irradiated targets and of energy depositions in the targets. Comparisons are made between simulations using different Geant4 physics models, experimental data, and other particle transport programs. Geant4 using the Binary Cascade model for inelastic nucleon reactions performs very well in these comparisons, but some issues with other models remain to be resolved if they are to be used for space radiation shielding applications. Results of Geant4 simulations of the transport of some relevant radiation field components through the hull of a simplified model of Columbus are also presented.
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| 12. |
- Gudowska, I, et al.
(författare)
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Low and high LET dose components in carbon beam
- 2006
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Ingår i: Radiation protection dosimetry. - : Oxford University Press (OUP). - 0144-8420 .- 1742-3406. ; 122:1-4, s. 483-484
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Tidskriftsartikel (refereegranskat)
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| 14. |
- Gudowska, I, et al.
(författare)
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NEUTRON PRODUCTION IN TISSUE-LIKE MEDIA AND SHIELDING MATERIALS IRRADIATED WITH HIGH-ENERGY ION BEAMS.
- 2007
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Ingår i: Radiat Prot Dosimetry. - : Oxford University Press (OUP). - 0144-8420 .- 1742-3406.
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Secondary neutrons produced in high-energy therapeutic ion beams require special attention since they contribute to the dose delivered to patient, both to tumour and to the healthy tissues. Moreover, monitoring of neutron production in the beam line elements and the patient is of importance for radiation protection aspects around ion therapy facility. Monte Carlo simulations of light ion transport in the tissue-like media (water, A-150, PMMA) and materials of interest for shielding devices (graphite, steel and Pb) were performed using the SHIELD-HIT and MCNPX codes. The capability of the codes to reproduce the experimental data on neutron spectra differential both in energy and angle is demonstrated for neutron yield from the thick targets. Both codes show satisfactory agreement with the experimental data. The absorbed dose due to neutrons produced in the water and A-150 phantoms is calculated for proton (200 MeV) and carbon (390 MeV/u) beams. Secondary neutron dose contribution is 0.6% of the total dose delivered to the phantoms by proton beam and at the similar level for both materials. For carbon beam the neutron dose contribution is 1.0 and 1.2% for the water and A-150 phantoms, respectively. The neutron ambient dose equivalent, H*(10), was determined for neutrons leaving different shielding materials after irradiation with ions of various energies.
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| 20. |
- Hollmark, M, 1975-, et al.
(författare)
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Influence of multiple scattering and energy loss straggling on the absorbed dose distributions of therapeutic light ion beams : I. Analytical pencil beam model.
- 2004
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Ingår i: Phys Med Biol. - : IOP Publishing. - 0031-9155 .- 1361-6560. ; 49:14, s. 3247-3265
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- The lateral and longitudinal distributions of absorbed dose of broad and narrowlight ion beams in water are investigated. An analytical algorithm based on thegeneralized Fermi–Eyges theory is developed and used to calculate the effectsof multiple scattering and range straggling on the dose distribution of light ionbeams in water. A first-order Gaussian multiple scattering and energy lossstraggling approach is generally sufficiently accurate for describing the lateraland longitudinal spread of the Bragg peak and the associated energy depositiondistribution of therapeutic light ion beams at ranges of clinical interest. Nuclearreactions are not taken into account in this study. The analytical algorithmgiven in the present study allows an accurate description of the radial spreadand the range straggling of light ions traversing matter. A verification of thisapproach by comparing with experimental data, Monte Carlo methods andother analytical techniques will be presented in a forthcoming paper.
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| 28. |
- Waligórski, M P R, et al.
(författare)
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Cellular parameters for track structure modeling of radiation hazard in space.
- 2004
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Ingår i: Adv Space Res. - : Elsevier BV. - 0273-1177 .- 1879-1948. ; 34:6, s. 1378-82
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Tidskriftsartikel (refereegranskat)abstract
- Based on irradiation with 45 MeV/u N and B ions and with Co-60 c rays, cellular parameters of Katz’s track structure modelhave been fitted for the survival of V79-379A Chinese hamster lung fibroblasts. Cellular parameters representing neoplastictransformations in C3H10T/1/2 cells after their irradiation with heavy ion beams, taken from earlier work, were also used to modelthe radiation hazard in deep space, following the system for evaluating, summing and reporting occupational exposures proposed in1967 by a subcommittee of NCRP. We have performed model calculations of the number of transformations in surviving cells, aftera given fluence of heavy charged particles of initial energy 500 MeV/u, penetrating thick layers of cells. We take the product of celltransformation and survival probabilities, calculated along the path lengths of charged particles using cellular survival and transformationparameters, to represent a quantity proportional to the ‘‘radiation risk factor’’ discussed in the NCRP document. The‘‘synergistic’’ effect of simultaneous charged particle transfers is accounted for by the ‘‘track overlap’’ mode inherent in the model ofKatz.
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