Health Physics Society Meeting, Pittsburgh, PA, July 13-17, 2008
Stacey McCord described the USTUR’s newly designed internal dosimetry database at the 53rd Annual Meeting of the Health Physics Society, Pittsburgh, PA, July 13-17, 2008. The database will be used to organize information from USTUR Registrant files (paper) in a format that is easily searchable. Additionally, three students from the Idaho State University (ISU)/USTUR Internal Dosimetry Research Team presented their graduate research: Naz Fallahian, George Tabatadze, and Liesl Germann
Upgrading the United States Transuranium and Uranium Registries’ health physics database
Stacey L. McCord (USTUR), Anthony C. James (USTUR)
The U.S. Transuranium and Uranium Registries (USTUR) has developed a newly structured database to provide fully searchable and comprehensive health physics data histories in each individual registrant case. The previous health physics database has been expanded from one ‘flat’ table – consisting of 12 fields – to eight specialized tables containing 179 individually searchable fields. These new tables divide all health physics observations into eight primary data types (each associated with a specific database form): air monitoring, in vivo bioassay, in vitro bioassay, contamination events, work site (intake/dose) assessments, external exposures, medical treatments, and narrative incident descriptions. Key design features are:
- Avoiding data entry ‘typos’ and unit conversion errors by utilizing dropdown menus and pre-programmed unit conversion factors.
- Optimizing data accessibility by storing principal information in individual ‘searchable’ fields, and
- Compatibility with searchable web publication of ‘de-identified’ case health physics data and linkage with USTUR’s other case information (case narratives, tissue radiochemistry results and pathology data).
The health physics database forms and steps taken to ensure quality data entry are presented, and broader application of these concepts is discussed. [USTUR-0243-08A]
Distributions of actinide tissue concentrations and dose rates in USTUR donors
Naz Fallahian (ISU), Anthony C. James (USTUR), Richard R. Brey (ISU)
The objective of this study is to evaluate the frequency distributions of actinide concentrations and internal dose rates measured in the tissues of the U.S. Transuranium & Uranium Registries’ (USTUR) deceased volunteer donors, for comparison with the generally much higher concentrations measured in the Russian MAYAK study cohort. These donors were radiation workers of the United States Department of Energy (DOE) facilities and were mainly exposed to actinide elements during their careers as a result of accidents. Frequency distributions of the wet concentrations of plutonium (239Pu) and americium (241Am) in the lungs, liver and skeleton of 285 voluntary tissue donors have been analyzed and their log-Gaussian statistical characteristics evaluated. Corresponding estimates of the log-normal frequency distributions of lung, liver and bone surface dose rates at the time of death have also been derived for this volunteer population. Their application to group individual donors into ‘high’ and ‘low’ categories of cumulative weighted external dose equivalent for the purpose of statistical analysis of proportionate cancer mortality in this population is discussed. [USTUR-0240-08A]
USTUR Case 0102 voxel phantom for external radiation detector response simulation
George Tabatadze (ISU), Richard R. Brey (ISU), Anthony C. James (USTUR), Neba Robinson Neba
The United States Transuranium and Uranium Registries (USTUR) is a resource of human tissue voluntarily donated by past workers with documented occupational actinide exposures. This research focuses on case 102 (a substantial accidental intake of 241AmO2) which was the first whole body donation to USTUR (in 1979). Half of this skeleton is encased in tissue equivalent plastic and serves as a unique “human phantom” for the calibration of whole body counting systems at United States Department of Energy (USDOE) and other laboratories (link). This paper reports progress in building a 3D voxel model of the case 0102 241Am phantom in order to simulate the experimental response of external planar germanium detectors variously positioned over the extremities (head, knee, ankle, and wrist). Segmentation of sequential CT-scan images and generation of surface rendered images of these parts of the case 0102 phantom are achieved using the 3D Doctor® Software package. The 3D surface model (Non-Uniformal Rational B-Spline, NURBS) is then voxelized using a MATLAB® code into a final computational phantom. This can be imported into a Monte Carlo code for radiation transport and detector response simulation. [USTUR-0241-08P]
Evaluation of the NCRP wound model using USTUR plutonium-contaminated wound cases
Liesl K. Germann (ISU), Richard R. Brey (ISU), Anthony C. James (USTUR)
In 2007, the National Council on Radiation Protection (NCRP) published report No. 156 titled, “Development of a Biokinetic Model for Radionuclide-Contaminated Wounds for Their Assessment, Dosimetry and Treatment.” This wound model represents the first attempt to develop a conceptual dosimetric model for radionuclide transport in the human body; however its retention coefficients, based heavily on animal experimental data, require specific testing to determine whether the NCRP wound model is a good predictor of plutonium behavior in human wound cases. In a poster study presented at the 2007 Annual Meeting Health Physics Society, we showed that the NCRP wound model retention coefficients yielded a highly significant statistical fit to the plutonium-contaminated U.S. Transuranium and Uranium Registry (USTUR) wound Case 0262 urinary and whole body data when no prior assumptions were made about the absorption category of the plutonium and IMBA combined the six absorption categories to find the best solution. This study builds on the 2007 study by testing the NCRP wound model’s retention coefficients’ ability to find a statistically significant dosimetric solution to additional USTUR plutonium-contaminated wound cases. The absorption categories were narrowed to those recommended by the NCRP for plutonium solution chemistry (strong, avid, particle, fragment) in order to obtain the ‘best’ maximum likelihood solution to the bioassay data. [USTUR-0242-08P]