Improving bioassay monitoring of excreta for selected radionuclides
Bioassay techniques are widely used for individual monitoring of incorporated radionuclides without sufficient photon emissions. Thereby, the uptake of radionuclides into the systemic parts of the body is measured by preferentially using urine samples. Currently applied methods, such as alpha spectrometry are often not very sensitive in detecting several radionuclides of high radiotoxicity. Alternatively, the ICP-MS methodology can be applied for selected radionuclides including uranium, thorium and actinides. Urged by this the IDEA project funded within the Euratom Research and Training Programme focused on exploring and validating the ICP-MS methodology in bio-assay monitoring. This study resulted into the development of guidelines for the improved performance of ICP-MS, whose adoption may allow rapid monitoring at lower limits of detection. Thereby, special recommendations were made related to the sampling of urine, the sample preparation, and implementation of the ICP-MS technique. One key issue that was also addressed involved the reliability of the biokinetic models used for internal dosimetry calculations. Since these models have been considered inconsistent particularly for radiologically important elements such as uranium, thorium, radium or lead, they were further investigated and improved. The formulated recommendations are expected to result in more reliable monitoring of incorporated radionuclides and the further development of realistic dose coefficients for uranium and thorium in internal dosimetry.
