A mesh type model for a Chinese indigenous dog applied to radiation dosimetry in uranium mining areas

The International Commission on Radiological Protection (ICRP) Reference Animals and Plants (RAPs) framework employs highly simplified geometries and limited size categories, introducing uncertainties in dose assessments for medium-sized terrestrial mammals in complex environments. To address this gap, a high-fidelity mesh type model of an adult male Chinese indigenous dog (15 kg) was developed based on contrast-enhanced CT imaging. The model comprises 18 major organs and tissues and was implemented in the PHITS Monte Carlo code for direct tetrahedral mesh transport. Absorbed fractions (AFs) and specific absorbed fractions (SAFs) for monoenergetic photons (0.01–4 MeV) and electrons (0.015–4 MeV) were calculated for all organs under internal irradiation—including both self-irradiation and cross-irradiation. External dose coefficients (DCs) were derived for key uranium-series radionuclides ( 226 Ra, 214 Pb, 214 Bi, and 214 Po) along with the naturally occurring radionuclide 40 K under three representative exposure scenarios in uranium mining areas: ground surface contamination with the animal in standing and prone postures, and lateral irradiation from a vertical mine wall. Results demonstrated significant influences of organ geometry, body posture, and source configuration on organ-level doses. Prone posture increased DCs for high-energy gamma emitters by up to ∼4% compared to standing, while lateral irradiation revealed strong position-dependent dose distributions—organs facing the source received doses comparable to or higher than those under ground contamination, whereas contralateral organs were substantially shielded. Organ-level doses varied considerably with posture and source geometry: superficial and small organs received higher DCs under ground contamination, while cephalic organs facing the source received the highest DCs under lateral wall irradiation. This anatomically realistic dog model fills a critical size gap in the ICRP RAPs and provides robust tools for site-specific radiation risk assessment of free-ranging canids (Canidae, e.g., dogs, wolves, foxes, and jackals) in contaminated uranium mining environments. The developed datasets support more accurate ecological protection under heterogeneous exposure conditions.