Personal dose equivalent conversion coefficients for neutron fluence over the energy range of 20 to 250 MeV

Journal Article · Thu Jan 01 04:00:00 EST 2009 · Radiation Protection Dosimetry

OSTI ID:956589

Mclean, Thomas D ^[1]; Justus, Alan L ^[1]; Gadd, S Milan ^[1]; Olsher, Richard H ^[2]; Devine, Robert T ^[2]

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1. Los Alamos National Laboratory
2. RP-2

Monte Carlo simulations were performed to extend existing neutron personal dose equivalent fluence-to-dose conversion coefficients to an energy of 250 MeV. Presently, conversion coefficients, H(p,slab)(10,alpha)/Phi, are given by ICRP-74 and ICRU-57 for a range of angles of radiation incidence (alpha = 0, 15, 30, 45, 60 and 75 degrees ) in the energy range from thermal to 20 MeV. Standard practice has been to base operational dose quantity calculations <20 MeV on the kerma approximation, which assumes that charged particle secondaries are locally deposited, or at least that charged particle equilibrium exists within the tally cell volume. However, with increasing neutron energy the kerma approximation may no longer be valid for some energetic secondaries such as protons. The Los Alamos Monte Carlo radiation transport code MCNPX was used for all absorbed dose calculations. Transport models and collision-based energy deposition tallies were used for neutron energies >20 MeV. Both light and heavy ions (HIs) (carbon, nitrogen and oxygen recoil nuclei) were transported down to a lower energy limit (1 keV for light ions and 5 MeV for HIs). Track energy below the limit was assumed to be locally deposited. For neutron tracks <20 MeV, kerma factors were used to obtain absorbed dose. Results are presented for a discrete set of angles of incidence on an ICRU tissue slab phantom.

• Research Organization: Los Alamos National Laboratory (LANL)
• Sponsoring Organization: DOE
• DOE Contract Number: AC52-06NA25396
• OSTI ID: 956589
• Report Number(s): LA-UR-09-01539; LA-UR-09-1539
• Journal Information: Radiation Protection Dosimetry, Journal Name: Radiation Protection Dosimetry; ISSN RPDODE; ISSN 0144-8420
• Country of Publication: United States
• Language: English

Related Subjects

61 RADIATION PROTECTION AND DOSIMETRY
APPROXIMATIONS
CARBON
CHARGED PARTICLES
CONVERSION
DOSE EQUIVALENTS
DOSES
ENERGY ABSORPTION
ENERGY RANGE
EQUILIBRIUM
HEAVY IONS
ICRU
KERMA
LIGHT IONS
MONTE CARLO METHOD
NEUTRON FLUENCE
NEUTRONS
NITROGEN
NUCLEI
OXYGEN
PARTICLE TRACKS
PROTONS
RADIATION DOSES
RADIATION TRANSPORT
RADIATIONS
RANGE
RECOILS
TRANSPORT