A rapid method for modeling the kinetics of radioactive progeny applied to thorium in the lungs

A general method for solving first-order compartmental models (recycling and nonrecycling) with any number of radioactive progeny is described and a heuristic proof of the method is provided. The method can be applied to any system where the progeny are assumed to behave isokinetically with the parent, as is the case with the biokinetic models currently recommended by the ICRP. The method is simple to apply, and its application to the modeling of radioactive progeny in the lungs following inhalation of thorium oxides is illustrated. The new ICRP respiratory tract model is used for this illustration.