| The ICRP 78 iodine model (base model) was assessed using the concepts of Akaike Information
Criterion (AIC). AIC was used to identify transfer coefficients and compartments in the base model
that are greatly affected by optimization and to evaluate the reliability of these model parameters.
The initial assumption is that the base model is an adequate representation of iodine metabolism
in the body. Optimizing the transfer coefficients should not cause large differences between the
base and optimized transfer coefficient values. However, the study found that optimization causes
large changes in the transfer coefficient values. The optimization of transfer rates describing iodine
translocation from “rest of the body” to “blood”, “blood” to “thyroid”, “thyroid” to the “rest of the
body”, and “blood” to “urine” produced pseudo-models with weighted relative likelihoods
consistently greater than the base model. There is weak evidence to support that the ICRP 78 iodine
model is the best approximation of the iodine dataset used in the study. Further efforts in internal
dosimetry modeling might benefit from looking at methods to identify transfer coefficients and
compartments a priori to create more reliable models.
Key Words: AIC, iodine, compartmental biokinetic models, internal dosimetry, model assessment |