Examples for underestimation of dose
There are some radionuclides where the old models may result in a significant underestimation of the dose. For example, the evaluation of whole-body measurements of inhaled Co-60 (type M, 5 µm AMAD) would result in an underestimation of the intake by about 40 % if the measurement is started one week after the intake. The underestimation of intake is compensated to some extent by the dose coefficient, but there would be still an underestimation of dose in the order of 15 – 20 %. The situation is similar for some other radionuclides which are measured by lung counting, such as U-235.
In the case of urinary excretion of inhaled Pu-239 (type M, 5 µm AMAD) there is a significant underestimation of intake especially in the first days after intake. So, a measured Pu-239 excretion rate of 1 mBq/d at the first day would result in an effective dose of 0.14 mSv according to the old models and 0.64 mSv according to the new models, respectively.
So, when using IDEAplus the error due to biokinetics can be reduced and thus the accuracy of dose assessment can be improved significantly.