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Dose Conversion Coefficients

External Photon1

We calculated dose coefficients for the International Commission on Radiological Protection (ICRP) reference pediatric phantoms externally exposed to mono-energetic photon radiation (x- and gamma-rays). Calculations were performed using Monte Carlo radiation transport techniques. Dose coefficients, i.e., organ absorbed dose per unit air kerma (mGy/mGy), were calculated for 28 organs and tissues including the active marrow (or red bone marrow) for 10 phantoms (newborn, 1-year, 5-year, 10-year, and 15-year-old male and female). Radiation exposure was simulated for 33 photon mono-energies (0.01 – 20 MeV) in six irradiation geometries: Antero-Posterior (AP), Postero-Anterior (PA), Right-Lateral (RLAT), Left-Lateral (LLAT), Rotational (ROT), and Isotropic (ISO).

Four charts of data

External organ and effective dose coefficients for age-dependent phantoms exposed to idealized photon beams in different irradiation geometries. 

External Neutron2

The ICRP Publication 116 includes adult male and female neutron fluence-to-dose coefficients for external exposures for the six idealized irradiation geometries (AP, PA, LLAT, RLAT, ROT, and ISO). These dose coefficients are not appropriate for children due to their smaller body weight and stature. We calculated neutron dose coefficients for pediatric phantoms (newborn, 1-, 5-, 10-, and 15-year-old) from the PHANTOMS library. Calculations were performed using the MCNP6 code for neutron energies between 0.001 eV and 10 GeV, including 28 organs, two bone tissues, and the overall whole-body effective dose.

Four charts showing dose coefficients

Neutron effective dose coefficients as a function of age for the (a) antero-posterior (AP) and (b) fully isotropic (ISO) geometries, and neutron organ dose coefficients for the six irradiation geometries for (c) active bone marrow and (d) stomach wall for the 10-year-old female and male phantoms, respectively.

Neutron effective dose coefficients as a function of age for the (a) antero-posterior (AP) and (b) fully isotropic (ISO) geometries, and neutron organ dose coefficients for the six irradiation geometries for (c) active bone marrow and (d) stomach wall for the 10-year-old female and male phantoms, respectively.

Selected References
  1. Chang LA, Simon SL, Jorgensen TJ, Schauer DA, Lee C. Dose coefficients for ICRP reference pediatric phantoms exposed to idealised external gamma fields. J Radiol Prot. 2017.

    [PubMed Abstract]
  2. Griffin K, Mille M, Lee C. Dose coefficients for children and young adolescents exposed to external neutron fields. J Radiol Prot Off J Soc Radiol Prot. 2018.

    [PubMed Abstract]
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