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Monte Carlo method used to determine scatter fractions for estimating secondary gamma-ray and X-ray photon dose equivalent rates

Published online by Cambridge University Press:  23 January 2014

L. Bourgois  and
N. Comte
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Abstract

The Monte Carlo MCNPX code is used to calculate the scatter fraction, making it possible to assess the scattered dose equivalent rate. Two materials are considered for the phantom: water and steel. The calculations are performed by considering beams of monoenergetic photons (in the range 10 keV to 10 MeV) and bremsstrahlung photons resulting from the interaction of electrons (30–900 keV) on a tungsten target. The variation of the scatter fraction is investigated as a function of the primary photon energy, the beam area at the phantom surface, the scattering angle, and filtration of the bremsstrahlung radiation. We note the shortcomings of the ISO standard issued in 2011, which does not take into account the beam area at the phantom surface, the scattering angle or the scattering materials, thus producing inconsistencies with the computed values given in this study and in the literature. Our values for the scatter fraction are comparable with those given in the literature (e.g. NCRP). As regards the bremsstrahlung radiation, we note the influence of filtration, in particular at low energies. The scatter fractions given here are compatible with the calculation of the ambient dose equivalent, whereas in the literature, they are systematically used for the calculation of air kerma rates. We also obtain scatter fractions for water that are higher by a factor of 5 compared with steel.

Keywords

scatteringX-rayMonte Carlo
Type
Article
Information
Radioprotection , Volume 49 , Issue 2 , April 2014 , pp. 107 - 113
Copyright
© EDP Sciences, 2014

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References

Antoni R., Bourgois L. (2013a) Principes généraux de protection contre l’exposition externe. In: Physique appliquée à l’exposition externe : dosimétrie et radioprotection. Springer, Paris.
Antoni R., Bourgois L. (2013b) Grandeurs et unités fondamentales de la dosimétrie externe. In: Physique appliquée à l’exposition externe : dosimétrie et radioprotection. Springer, Paris.
ICRU Report 57 (1998) Conversion coefficients for use in radiological protection against external radiation. Pergamon Press, Oxford.
ISO Norme NF C 15-160 (2011) Installation pour la production et l’utilisation de rayonnements X – Exigences de radioprotection.
NCRP Report 49 (1976) National Council on Radiation Protection and Measurements Structural Shielding Design and evaluation for Medical use of X-Rays and Gamma-Rays up to 10 MeV.
NCRP Report 147 (2005) National Council on Radiation Protection and Measurements Structural Shielding Design for Medical X-Ray Imaging Facilities.
Noto, K., Koshida, K., Iida, H., Yamamoto, T., Kobayashi, I., Kawabata, C. (2009) Investigation of scatter fractions for estimating leakage dose in medical X-ray imaging facilities, Radiol. Phys. Technol. 2, 138-144. Google ScholarPubMed
Pelowitz D.B. (2005) MCNPX user’s manual LA-CP-05-369.
Simpkin, D.J., Dixon, R.L. (1998) Secondary shielding barriers for diagnostic X-Ray facilities : scatter and leakage revisited, Health Phys. 74 (3), 350-365. Google ScholarPubMed
White M.C. (2002) Photoatomic data library MCPLIB04: a new photoatomic library based on data from ENDF/B-VI release 8. Los Alamos National Laboratory Memorandum No. X-5:MCW-02-111.