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A -- RESEARCH TO VALIDATE THE ELECTRON PARAMAGNETIC RESONANCE (EPR) METHOD FOR BONE AND TOOTH ENAMEL DOSIMETRY SOL 52SBNB8C1100 POC Joan M. Smith, (301) 975-6458 WEB: NIST Contracts Homepage, http://www.nist.gov/admin/od/contract/contract.htm. E-MAIL: NIST Contracts Office, Contract@nist.gov. The National Institute of Standards and Technology (NIST) has a requirement for research to validate the EPR method for bone and tooth enamel dosimetry. This work involves the establishment, through rigorous evaluation, testing and analysis, of a standardized protocol for the retrospective assessment of the absorbed dose to tooth enamel using EPR spectrometry. The establishment of the standard protocol requires a concerted effort on three fronts: validation of all aspects of the EPR method for biodosimetry; creation of NIST-quality standard reference materials for the calibration and use of EPR spectrometers employed in the analysis; and, assessment of the performance characteristics of alanine dosimetry as a primary method for high-precision calibration of radiation sources used in EPR biodosimetry. Validation of the EPR method for tooth dosimetry has not been demonstrated in the scientific literature. The quality of the results derived from EPR determinations is of critical importance to epidemiological studies from which recommendations are made for occupational exposures. Validation of the chemical, physical and computational steps which comprise the EPR method for biodosimetry necessitates an exhaustive study of all technical aspects, which include (but is not limited to): sample particle size, sample preparation, sample chemical and physical treatment, EPR spectral data anipulation and analysis, interferences (e.g., x-rays, sunlight), additive reirradiation, uncertainty analysis. EPR spectrometer calibration and use must be linked to national standards via a suitable standard reference material. A primary reference material and transfer reference materials must be fabricated, evaluated, and calibrated. The EPR reference material shall be based on nitroxide radicals as the active component. Prototype standard reference materials must be fabricated, performance characteristics must be evaluated, and a protocol for the use of the reference material must be prepared. Radiation source calibration and use must be linked to national standards via a suitable standard reference material. The long-term reliability of the transfer material is critical for the traceability of radiation measurements to national standards. The transfer dosimetry system shall be alanine dosimetry. The long-term performance characteristics of the alanine system must continue to be monitored in order to assess effects of environmental influences and modify the system appropriately. The technical staff performing the research are required to have their PhD in a Physical Science, have at least five years experience in EPR spectrometry and radiation dosimetry, and shall have as a resource, expertise in the health effects of ionizing radiation and epidemiology. The work necessitates the use of NIST technical facilities. Execution of these tasks requires a full working knowledge of three Bruker EPR spectrometers, models ESP300E, ECS106 & EMS104, and a demonstrated competency in the proper use of free-standing, pool-based and therapy-type Cobalt-60 radiation sources. Demonstrated skills in analytical chemistry are also necessary to complete the tasks. Tasks required for the first year are as follows: 1. Acquire equipment and materials needed for enamel grain size study. 2. Set up equipment and ensure its proper operation. 3. Investigate the dependence of the background signal on the tooth enamel grain preparation method. 4. Investigate the dependence of the radiation-induced signal on the tooth enamel grain preparation method. 5. Investigate the effect of grain size on the EPR microwave field stability. 6.Analyze the dependence of the measured EPR signals on the chemical method used in tooth enamel grain preparation procedure. 7. Devise a rational basis for the observed tooth enamel grain preparation effects. 8. Formulate recommendations regarding the grain size. 9. Formulate the optimum chemical procedure for tooth enamel grain preparation. 10. Explore possibilities for further improvement of the performance characteristics of alanine dosimetry. 11. Conduct long-term monitoring of the alanine system to ensure its reliability. 12. Explore possibilities for further improvement of the performance characteristics of alanine dosimetry. 13. Recommend appropriate tests of the alanine system to ensure its long-term reliability. 14. Develop a standardized procedure for precise determination of nitroxide radicals two independent (non-EPR) methods. -- The period of performance for this requirement is for twelve months with four twelve month options to renew. -- See Number Note 22 and 26. -- It is the Government's intent to negotiate with John Hopkins University, Baltimore, Maryland, the only responsible source that can satisfy the agency's requirements. (0154)

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