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Estimation of Neutron Dose Conversion Coefficients for a Voxel Phantom with MCNPX. Valery Taranenko and Maria Zankl, GSF—Research Center for Environment and Health, Germany. Voxel Phantom. Voxel dimensions X-Y-Z 3D array of organ IDs ~ 10 MB in binary Organ ID => Material
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Estimation of Neutron Dose Conversion Coefficientsfor a Voxel Phantom with MCNPX Valery Taranenko and Maria Zankl,GSF—Research Center for Environment and Health, Germany
Voxel Phantom • Voxel dimensions X-Y-Z • 3D array of organ IDs ~ 10 MB in binary • Organ ID => Material • Material definitions density,isotopes
MCNPX and Voxels • Done via repeated structures (v2.5.0) • Easy conversion • Successfully tested for photon-electron transport with EGSnrc and PENELOPE • Refer to Taranenko et al. in MC2005 Proceedings voxel 3D lattice
Transport parameters • MCNP “low” energy transport ≤ 20 MeV(table-based) • Neutron-photon mode • Cutoff energies: • Neutron default (0) • Photon 1 keV • Scoring via +F6 tally (track-length flux + heating numbers)
MCNPX XS libraries • Explicit isotope composition for 27 materials • DLC-0205/004 package: • LA150N (ENDF/B-VI.6) 1H, natC, 14N, 16O, 31P, natCa, 56Fe • ENDF60 (ENDF/B-VI)23Na; natural Mg, S, Cl and K;127I • RMCCSA (ENDL 85)natAr • S(α,β) thermal scattering treatment for 1H in light water @ 300 K from table LWTR.01T(Improved S(α,β) thermal treatment in MCNPX) • Photoatomic: EL03 + EPDL97-based
Adjusted Voxel Phantoms: Klara and Godwin • Based on CT data: woman and man • Adjusted to ICRP 89 Reference Man (V, m, h) • Refer toZankl et al.in ICMP 2005presentation:T 5.3 at 10:35
Results 1 10 million of primary neutrons
Summary • Godwin/MCNPX vs VIP-Man/MCNP vs ICRP74 • Typical difference 10-20% • Up to 50-70% at 0.1-3 MeV • Acceptable speed (3-GHz Pentium 4) ~100,000 showers per min • Memory requirements (problem dependent)< 500 MB • TO DO: • Sensitivity to phantom geometry • RBM dose • > 20 MeV