Modeling of internal dose from an insoluble cesium

Manabe, Kentaro   ; Matsumoto, Masaki*

If an insoluble particle bearing radioactive cesium is incorporated into the human body, the radioactive nuclei included in the particle will move as a single particulate material without being distributed throughout the body by dissolving to blood or tissue fluid like soluble cesium. Because commonly applied methods for estimation of the numbers of decays are designed for the average behavior of large number of nuclei, the existing methods cannot be applied for insoluble cesium particles. In this study, we developed a method simulating a stochastic movement of a single particle in the body, and constructed an improved biokinetic model for insoluble particles. This method enables to estimate the numbers of decays considering the stochastic movement of the particle, and organ absorbed doses by combining the numbers of decays and corresponding S values. Repetitive execution of this procedure makes it possible to evaluate a probability density function of exposure dose.