Intake and Dose Assessment

DOE-HDBK-1184-2004

5 INTAKE AND DOSE ASSESSMENT

5.1 Biokinetic and Dosimetric Models

A biokinetic model describes in quantitative terms the retention and transport of a material

in the body. A dosimetric model prescribes how to use the biokinetic and radiation

transport models to quantify the dose to specific organs and tissues and how to calculate

effective dose. The biokinetic model used in ICRP 78 is recommended to evaluate intakes

of STC. The dosimetric models for STC are described primarily in ICRP 67 and 71. The

STC biokinetic and dosimetric models will be briefly reviewed in this section and a detailed

benchmark calculation is provided in Appendix B. The relevant ICRP publications should

be consulted for a more detailed discussion of the models and their application.

The STC biokinetic model may be broken down into three major components:

The respiratory tract model from ICRP 66;

The systemic retention and excretion model from ICRP 67 and 78; and

The gastrointestinal (GI) tract model from ICRP 30 and 78.

An example of how these models are coupled is shown in Figure 5- 1. Inhaled aerosols of

insoluble metal tritides (IMTs) that are initially deposited in the respiratory tract are:

mechanically cleared from the body (e.g., by blowing the nose);

dissolved and absorbed into the bloodstream; or

mechanically cleared to the GI tract.

Figure 5-1. Simplified Overview of How the Major Components of the ICRP 78 Biokinetic

Model for Insoluble Metal Tritides are Connected.