IMBA-Expert: Concepts and capabilities for the interpretation of
bioassay data
Alan Birchall, NRPB
Abstract:
IMBA-Expert: Concepts and Capabilities for the Interpretation of Bioassay Data
A Birchall1, A C James2, J W Marsh1, F M G Smith1, M D Dorrian1, N S Jarvis3,
M S Peace4, and M R B Puncher1
1 National Radiological Protection Board, Chilton, Didcot, Oxon. OX11 0RQ. UK
2 ACJ & Associates, Inc. 129 Patton Street, Richland, WA 99352, USA
3 1096 Covington Place, Allison Park, PA 15101-1607, USA
4 British Nuclear Fuels plc. Sellafield, Seascale, Cumbria CA20 1PG. UK
In recent years, ICRP has produced a new set of biokinetic models that are more realistic and scientifically justifiable than their predecessors. Since January 2000, legislation within the UK has resulted in ADS's (Approved Dosimetry Services for Internal Dosimetry) using these new models to assess the dose received by a worker. In 1997, a collaboration between British Nuclear Fuels, Westlakes Research Institute, and the National Radiological Protection Board started with the aim of producing a suite of modules (IMBA: Integrated Modules for Bioassay Analysis) to aid the interpretation of bioassay data. These modules work together to implement the latest ICRP models in order to (a) estimate intakes from bioassay measurements and (b) calculate the resulting internal dose. The modules have since been completed, tested extensively for quality assurance, and are currently in use by the UK ADSs.
While the modules themselves are very powerful and flexible, they do require significant knowledge and expertise to implement them correctly. Many organisations do not have sufficient time or resources to allocate to this task, and so recent effort has been directed towards the development of user-friendly software that uses the IMBA modules to obtain the appropriate results. Such an approach has the advantage that the software is easy to use, and can be customised directly to meet a particular need, while still retaining the reliability of the IMBA modules themselves. This approach has been used to develop a general dosimetry program for one organisation which implements 5 radionuclides (IMBA-DERA), and a package specifically designed to deal with mixtures of uranium isotopes (IMBA-URAN).
More recently, interest in the IMBA approach has spread beyond the UK. In May 2001, following extensive scientific discussions with internal dosimetrists at many of its nuclear sites, the United States Department of Energy undertook to finance a major implementation of the IMBA modules (IMBA EXPERTTM USDOE Edition). This project is ambitious and requires major extension and development of previous techniques e.g. enhanced flexibility and ease of use; the ability to deal with incomplete bioassay samples; graphical and statistical output; intake via wound calculations and the calculation of doses from up to 30 associated radionuclides automatically. It is also planned to extend the program further to deal with the estimation of intakes from different types of bioassay data simultaneously (e.g. urine and faecal excretion data) and introduce Bayesian techniques for interpretation of data. One of the main advantages of the IMBA approach is the flexibility in which the modules can be customised for different purposes. One example involved collaboration with the Centres for Disease Control and Prevention (US) to customise the IMBA modules for use in the assessment of risk for the US Worker Compensation Scheme. It is also planned to work with Ontario Power Generation Nuclear (Canada) on a version of IMBA ExpertTM for specific application to CANDU reactor operation.
The aim of this talk is to illustrate the concepts and capabilities of the IMBA methodology, describe the progress made to date with its implementation; and outline plans for its future development.
