Initial investigation OF 222Rn in the Tbilisi urban environment.

Georgia has geological formations with high uranium content, and several buildings are built with local materials. This can create potentially high radon exposures. Consequently, studies to mitigate these exposures have been started. This study presents a preliminary investigation of radon in Tbilisi, the capital of Georgia. An independent radiological monitoring program in Georgia has been initiated by the Radiocarbon and Low-Level Counting Section of I. Javakhishvili Tbilisi State University with the cooperation of the Environmental Monitoring Laboratory of the Physics/Health Physics Department at Idaho State University. At this initial stage the E-PERM systems and GammaTRACER were used for the measurement of gamma exposure and radon concentrations in air and water. Measurements in Sololaki, a densely populated historic district of Tbilisi, revealed indoor radon (222Rn) concentrations of 1.5-2.5 times more than the U.S. Environmental Protection Agency action level of 148 Bq m(-3) (4 pCi L(-1)). Moreover, radon-in-air concentrations of 440 Bq m(-3) and 3,500 Bq m(-3) were observed at surface borehole openings within the residential district. Measurements of water from various tap water supplies displayed radon concentrations of 3-5 Bq L(-1) while radon concentrations in water from the hydrogeological and thermal water boreholes were 5-19 Bq L(-1). In addition, the background gamma absorbed dose rate in air ranged of 70-115 nGy h(-1) at the radon test locations throughout the Tbilisi urban environment.

Calculation of dose coefficients for radionuclides produced in a spallation neutron source utilizing NUBASE and the evaluated nuclear structure data file databases.

Based on a mercury spallation neutron source target, the UNLV Transmutation Research Program has identified 72 radionuclides with a half-life greater than or equal to a minute as lacking an appropriate reference for a published dose coefficient according to existing radiation safety dose coefficient databases. A method was developed to compare the nuclear data presented in the ENSDF and NUBASE databases for these 72 radionuclides. Due to conflicting or lacking nuclear data in one or more of the databases, internal and external dose coefficient values have been calculated for only 14 radionuclides, which are not currently presented in Federal Guidance Reports Nos. 11, 12, and 13 or Publications 68 and 72 of the International Commission on Radiological Protection. Internal dose coefficient values are reported for inhalation and ingestion of 1 microm and 5 microm AMAD particulates along with the f1 values and absorption types for the adult worker. Internal dose coefficient values are also reported for inhalation and ingestion of 1 microm AMAD particulates as well as the f1 values and absorption types for members of the public. Additionally, external dose coefficient values for air submersion, exposure to contaminated ground surface, and exposure to soil contaminated to an infinite depth are also presented.

Quality assurance methods and procedures used to verify consistency in calculating dose coefficients.

The development of a spallation neutron source with a mercury target will lead to the production of rare radionuclides. The dose coefficients for many of these radionuclides have not yet been published. A collaboration of universities and national labs has taken on the task of calculating dose coefficients for the rare radionuclides using the software package DCAL. The working group developed a procedure for calculating dose coefficients and a quality assurance (QA) program to verify the calculations completed. The first portion of this QA program was to verify that each participating group could independently reproduce the dose coefficients for a known set of radionuclides. The second effort was to divide the group of rare radionuclides among the independent participants in a manner that assured that each radionuclide would be redundantly and independently calculated, and the results subsequently be submitted for publication in a separate manuscript. The final aspect of this program was to resolve any discrepancies arising among the participants as a group. The output of the various software programs for six QA radionuclides, 144Nd, 201Au, 50V, 61Co, 41Ar, and 38S were compared among all members of the working group. Initially, a few differences in outputs were identified. This exercise identified weaknesses in the procedure, which has since been revised. After the revisions, dose coefficients were calculated and compared to published dose coefficients with good agreement. The present efforts involve generating dose coefficients for the rare radionuclides anticipated to be produced from the spallation neutron source should a mercury target be employed.

Are all troponin assays equivalent in the emergency department?

INTRODUCTION: Cardiac-specific troponins (cTn) are recently-introduced, sensitive and specific markers of myocardial injury, and their absence should allow to safely exclude a coronary event. Various assays are commercially available but the relative advantage of each is not clear. Our objective was to compare the reliability of the two most commonly used troponin assays (cTnI and cTnT), in the emergency department (ED) for clinical decision when myocardial infarction (MI) or acute coronary syndrome (ACS) is suspected. METHODS: This prospective study included all patients arriving at the ED over a six-month period with chest pain or symptoms suggesting MI or ACS, in which diagnosis could not be confirmed due to absence of characteristic ECG features. All patients were tested with at least one of the two troponin assays available at the ED. RESULTS: Of the 54 included patients, ten (19%) were eventually diagnosed with MI/ACS. Qualitative assays for cTnI and cTnT identified the MI/ACS patients by both assays (respective positive predictive values of 0.5 and 0.7, and negative predictive values of 1.0 and 0.9). However, these assays were only partially correlated (R equals 0.49) and differed significantly. The quantitative assay for cTnI, but not for cTnT, discerned those who had MI/ACS (group A) from those who had other condition (group B) by their troponin levels (MI/ACS - 17.2 plus or minus 23.8 ng/ml versus others - 0.37 plus or minus 0.91 ng/ml, p is less than 0.001). CONCLUSION: In the ED, bedside assays of troponins are invaluable tools for the clinician, and their use is cost-effective. However, in the recommended cutoffs levels, only troponin I but not troponin T allowed the safe discharge of patients not requiring acute hospital care.