Integration of ICRP OIR Models Into the iDose 2 Dosimetry System

Introduction: The iDose 2 dosimetry system is a tool for assessing the doses of internal irradiation of workers under the current individual dosimetry control (IDC). In this system, according to a series of measurements of the activity of radionuclides in biological objects (including those not exceeding the detection limit of the measurement technique) and information on contact times and types of compounds, estimates of the committed effective dose equivalent (CEDE) of internal irradiation, as well as their uncertainties, are made based on the Bayesian approach. It is possible to integrate practically any biokinetic models of the behavior of radionuclides in the human body, presented in the form of a system of ordinary differential equations (ODEs) with constant transition coefficients between compartments, into the iDose 2 dosimetry system without changing the source code.

Purpose: Integration of new combined biokinetic models for the list of radionuclides: H-3, Sr-90, Cs-137, Pu-238, Pu-239 and Am-241 from Publications 100, 130, 134, 137 and 141 of the ICRP (conventionally called the series Occupational Intakes of Radionuclides (OIR)), for ingestion and inhalation routes of intake with AMAD = 1 and 5 microns.

Material and methods: For each variant of the biokinetic model, the functions of retention/removal of radionuclides were found through the eigenvectors and eigenvalues of the matrix describing the ODE system.

Results: A total of 65 new biokinetic models and 180 functions of radionuclide retention/removal in the form of a sum of exponents were integrated and quality control was carried out.