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Thallium-201 for medical use

Description: From 20th annual meeting of the Society of Nuclear Medicine; Miami Beach, Florida, USA (12 Jun 1973). The advantages of using /sup 201/Tl as an analog for K in diagnostic tracer studies are discussed. It is pointed out that the photons of /sup 201/Tl are detected with high efficiency and resolution in a lowenergy collimator gamma camera system. Tissue distribution studies in goats show that /sup 201/Tl concentrates in the renal medulla and would be of value in kidney function studies, has a differential uptake in melanomas, and concentrates in the myocardium, making it advantageous for myocardial visualization and function studies. (CH)
Date: January 1, 1973
Creator: Lebowitz, E.; Greene, M.W.; Bradley-Moore, P.; Atkins, H.; Ansari, A.; Richards, P. et al.
Partner: UNT Libraries Government Documents Department

COUPP - a search for dark matter with a continuously sensitive bubble chamber

Description: We propose to construct and operate a 60-kg room temperature CF{sub 3}I bubble chamber as a prototype dark matter (WIMP) detector. Operating in weakly-superheated mode, the chamber will be sensitive to WIMP induced nuclear recoils above 10 keV, while rejecting background electron recoils at a level approaching 10{sup 10}. We would first commission and operate this chamber in the MINOS near detector hall with the goal to demonstrate stable operation and measure internal contamination and any other backgrounds. This chamber, or an improved version, would then be relocated to an appropriate deep underground site such as the Soudan Mine. This detector will have unique sensitivity to spin-dependent WIMP-nucleon couplings, and even in this early stage of development will attain competitive sensitivity to spin-independent couplings.
Date: January 1, 2007
Creator: Collar, Juan,; Crum, Keith; Mishra, Smriti; Nakazawa, Dante; Odom, Brian; Rasmussen, Julia et al.
Partner: UNT Libraries Government Documents Department

Reliability of Current Biokinetic and Dosimetric Models for Radionuclides: A Pilot Study

Description: This report describes the results of a pilot study of the reliability of the biokinetic and dosimetric models currently used by the U.S. Nuclear Regulatory Commission (NRC) as predictors of dose per unit internal or external exposure to radionuclides. The study examines the feasibility of critically evaluating the accuracy of these models for a comprehensive set of radionuclides of concern to the NRC. Each critical evaluation would include: identification of discrepancies between the models and current databases; characterization of uncertainties in model predictions of dose per unit intake or unit external exposure; characterization of variability in dose per unit intake or unit external exposure; and evaluation of prospects for development of more accurate models. Uncertainty refers here to the level of knowledge of a central value for a population, and variability refers to quantitative differences between different members of a population. This pilot study provides a critical assessment of models for selected radionuclides representing different levels of knowledge of dose per unit exposure. The main conclusions of this study are as follows: (1) To optimize the use of available NRC resources, the full study should focus on radionuclides most frequently encountered in the workplace or environment. A list of 50 radionuclides is proposed. (2) The reliability of a dose coefficient for inhalation or ingestion of a radionuclide (i.e., an estimate of dose per unit intake) may depend strongly on the specific application. Multiple characterizations of the uncertainty in a dose coefficient for inhalation or ingestion of a radionuclide may be needed for different forms of the radionuclide and different levels of information of that form available to the dose analyst. (3) A meaningful characterization of variability in dose per unit intake of a radionuclide requires detailed information on the biokinetics of the radionuclide and hence is not feasible for many ...
Date: October 1, 2008
Creator: Leggett, Richard Wayne; Eckerman, Keith F & Meck, Robert A.
Partner: UNT Libraries Government Documents Department

Bayesian methods for interpreting plutonium urinalysis data

Description: The authors discuss an internal dosimetry problem, where measurements of plutonium in urine are used to calculate radiation doses. The authors have developed an algorithm using the MAXENT method. The method gives reasonable results, however the role of the entropy prior distribution is to effectively fit the urine data using intakes occurring close in time to each measured urine result, which is unrealistic. A better approximation for the actual prior is the log-normal distribution; however, with the log-normal distribution another calculational approach must be used. Instead of calculating the most probable values, they turn to calculating expectation values directly from the posterior probability, which is feasible for a small number of intakes.
Date: September 1, 1995
Creator: Miller, G. & Inkret, W.C.
Partner: UNT Libraries Government Documents Department

Power Functions Relating Excretion to Body Burden

Description: Formulae necessary to relate the quantity of radionuclides excreted to that assimilated in exposures that are acute and those that are multiple or continuous are derived from power function relationships. Particular attention is given to providing equations having variables for which the bioassayer can easily derive numerical values. This paper presents this data.
Date: February 21, 2003
Creator: Sanders, S.M. Jr.
Partner: UNT Libraries Government Documents Department

Distribution of environmental plutonium in the Trinity Site ecosystem after 27 years

Description: From 3rd international congress of the International Radiation Protection Association meeting; Washington, District of Columbia, USA (9 Sep 1973). Results are presented for a radioecological survey of the Trinity Site environs, where the world's first (July 1945) atomic bomb was detonated. The temporal behavior of the low environmental levels of the plutonium produced by this detonation are discussed. The data from this study were compared with similar data obtained in the Trinity Site environs nearly 20 years ago. The major change which was observed was an increased migration of Pu into the soils. Concentrations of Pu in vegetation and rodents were too low to make valid comparisons. (auth)
Date: January 1, 1973
Creator: Hakonson, T.E. & Johnson, L.J.
Partner: UNT Libraries Government Documents Department

Distribution of plutonium in liquid waste disposal areas at Los Alamos

Description: From third international congress of the International Radiation Protection Association meeting; Washington, District of Columbia, USA (9 Sep 1973). An ecological investigation is described of plutonium in the Los Alamos Scientific Laboratory environs. Data are presented on the distribution of plutonium in the alluvial sediments, water, vegetation, and rodents from Mortandad Canyon, an area which has been used for liquid waste disposal for 10 years. (auth)
Date: January 1, 1973
Creator: Hakonson, T.E.; Johnson, L.J. & Purtymun, W.D.
Partner: UNT Libraries Government Documents Department

Comparison of LaBr3:Ce and NaI(Tl) Scintillators for Radio-Isotope Identification Devices

Description: Lanthanum halide (LaBr3:Ce) scintillators offer significantly better resolution (<3 percent at 662 kilo-electron volt [keV]) relative to sodium iodide (NaI(Tl)) and have recently become commercially available in sizes large enough for the hand-held radio-isotope identification device (RIID) market. There are drawbacks to lanthanum halide detectors, however. These include internal radioactivity that contributes to spectral counts and a low-energy response that can cause detector resolution to be lower than that of NaI(Tl) below 100 keV. To study the potential of this new material for RIIDs, we performed a series of measurements comparing a 1.5?1.5 inch LaBr?3:Ce detector with an Exploranium GR 135 RIID, which contains a 1.5-2.2 inch NaI(Tl) detector. Measurements were taken for short time frames, as typifies RIID usage. Measurements included examples of naturally occurring radioactive material (NORM), typically found in cargo, and special nuclear materials. Some measurements were noncontact, involving short distances or cargo shielding scenarios. To facilitate direct comparison, spectra from the different detectors were analyzed with the same isotope identification software (ORTEC ScintiVision TM). In general, the LaBr3:Ce detector was able to find more peaks and find them faster than the NaI(Tl) detector. To the same level of significance, the LaBr3:Ce detector was usually two to three times faster. The notable exception was for 40K containing NORM where interfering internal contamination in the LaBr3:Ce detector exist. NaI(Tl) consistently outperformed LaBr3:Ce for this important isotope. LaBr3:Ce currently costs much more than NaI(Tl), though this cost-difference is expected to diminish (but not completely) with time. As is true of all detectors, LaBr3:Ce will need to be gain-stabilized for RIID applications. This could possibly be done using the internal contaminants themselves. It is the experience of the authors that peak finding software in RIIDs needs to be improved, regardless of the detector material.
Date: July 31, 2006
Creator: Milbrath, Brian D.; Choate, Bethany J.; Fast, Jim E.; Hensley, Walter K.; Kouzes, Richard T. & Schweppe, John E.
Partner: UNT Libraries Government Documents Department