Techniques to monitor radionuclides in the general public
Radionuclides can enter the human body through a number of different pathways, including, but not limited to, inhalation and ingestion. Only periodic monitoring can ensure that exposure to radiation from such sources does not pose a threat to human health. This is particularly relevant for members of the nuclear industry workforce. Four research centres spread throughout Europe gathered forces during the IDEA project to investigate new techniques in internal dosimetry. Support was provided by the EURATOM Programme. The findings have been summarised by the KFKI Atomic Energy Research Institute associated with the Hungarian Academy of Sciences. With respect to in vivo monitoring, High purity germanium (HPGe) detectors were the best solution for low photon energy emitters like plutonium-239 (239Pu). Use of silicon-based detectors helped overcome temperature limitations. To keep costs to a minimum, it is possible to substitute thallium-activated sodium iodide (NaI(Tl)) scintillation detectors when spectral resolution requirements can be relaxed. Numerical calibration of these instruments is strongly recommended since several distinct advantages over calibration with physical phantoms were identified during IDEA. In vivo monitoring can also be complemented by bioassay methods. In this domain, Inductively coupled plasma mass spectroscopy (ICP-MS) has emerged to take the place of older techniques like beta counting. In the context of IDEA, guidance was established for the application of ICP-MS to measure uranium, thorium and other elements. In fact, by employing high resolution sector field ICP-MS, it was possible to reduce time and cost requirements without sacrificing accuracy. This approach is therefore advocated for use with the general public.
