Characterisation, implementation and quality assurance of biokinetic models. The experience of the CONRAD Task Group 5.2.

CONRAD (Coordinated Network on Radiation Dosimetry) was an action funded by the European Commission within the 6 Framework Programme in order to link groups undertaking research relating to radiation dosimetry at workplaces. Workpackage 5 of CONRAD was dedicated to internal dosimetry. Task Group 5.2 "Research Studies on Biokinetic Models" dealt with the development, implementation, characterization and quality assurance of biokinetic models. The new ICRP model of the human alimentary tract (HATM), the new NCRP model for contaminated wounds, new systemic recycling models of the biokinetics of radioisotopes of polonium and plutonium presented in the scientific literature were implemented into the computer codes of five different institutions. Also new systemic biokinetic models for zirconium and molybdenum, developed on the basis of own results from stable tracer studies, were implemented. The excellent agreement among the results obtained by the different groups indicate that all the present models can be easily implemented into available software codes and that the outputs are independent of the computational approach used. It was also possible to better characterize the systemic models of plutonium by use of a partition factor expressing the relative distribution of material between skeleton and liver, and the NCRP wound model, by derivation of the exact analytical solutions for the wound retention resulting from the model formulation.