ABSTRACT
As seen in Chapter 4, estimation of absorbed dose requires integration of each organ’s time-activity curve out to infinity (or at least to many times the physical half-life of the radiolabel). Prior to such integration, a mathematical method is required to allow interpolation and extrapolation of necessarily sparse animal and human data sets such as a(t), u(t), or A(t). A number of different types of mathematical pictures exist, and several software packages are available from universities and other resources. This chapter describes various model types and several of these resources. Examples of some of the model styles are included. It is important to mention that any model, no matter how well justified conceptually, can be criticized for being limited or overly specific. Thus, the particular choice may be difficult to make.
