Internal dose assessments - Concepts, models and uncertainties

In contrast to external dosimetry, which can be based on measurement of operational quantities directly related to the effective dose (mSv), the assessment of doses due to intakes of radionuclides relies on the measurement of activities (Bq) and subsequent modelling. The methodology and the models are published by the International Commission on Radiological Protection (ICRP) and are later implemented in national regulations. This paper describes the general concepts for assessment of internal occupational exposure and diagnostic nuclear medicine applications using biokinetic and dosimetric models. The current changes in the models which are presented in the OIR series (Occupational Intakes of Radionucldes) of ICRP are outlined and information on the uncertainties in internal dose assessment are presented.