Interpretation of Whole-Body Monitoring and Bioassay Data

Abstract

The intake of radioactivity into the body presents many challenges for the dosimetrist who seeks to determine the intake and hence the dose received by the person. Investigation and other levels can be set by using the human biokinetic models proposed by the International Commission on Radiological Protection (ICRP). Measurement of radioactivity in air can be related to uptake and dose based upon these models but with large uncertainties due to the wide spatial variations in activity in the workplace. The use of in vivo monitoring, including body monitoring and bioassay measurements, is necessary if a significant intake is anticipated or occurs. The measurement of particle size, chemical form and radioactivity has to be interpreted using the ICRP models initially. However, individuals vary anatomically and in other ways which affect the metabolism of radionuclides and it is important to obtain the best estimate of intake which is consistent with all the measurements made, taking into account any uncertainties. The assessment of intakes for a wide variety of radionuclides, including tritium, fission products, uranium, thorium, plutonium and higher actinides, will be examined against a changing background of biokinetic models produced by ICRP. Comparisons between techniques used in different European laboratories will be considered as the basis for a unified approach to internal dose assessment.