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The purpose of this work is to assess accuracy and compare the performance of radionuclide calibrators (RNCs) used in nuclear medicine departments in Serbia. Testing of the RNCs included verification of measurement accuracy, as well as analysis of routinely used quality control protocols, by using the certified radioactivity standards (57Co, 137Cs). RNCs performances were assessed with 99mTc through comparison of reference value for radionuclide activity and RNC measurements. Results of the intercomparison revealed that RNCs, 15 in total, are accurate within 10% in vial geometry and within 15% in syringe geometry. Most of them showed similar performance. The results revealed that container geometry is an important influencing parameter in the accuracy of activity measurement. Obtained results indicate a need for regular calibration and implementation of Quality Control program in order to achieve and maintain the accuracy of activity measurements in nuclear medicine.

The probabilities of locating peaks with a high relative peak-area uncertainty were determined empirically with nine types of peak-location software used in laboratories engaged in gamma-ray spectrometry measurements. It was found that it is not possible to locate peaks with a probability of 0.95, when they have a relative peak-area uncertainty in excess of 50%. Locating peaks at these relatively high peak-area uncertainties with a probability greater than 0.95 is only possible in the library-driven mode, where the peak positions are supposed a-priori. The deficiencies of the library-driven mode and the possibilities to improve the probabilities of locating peaks are briefly discussed. © 2019 Elsevier Ltd

Open-faced charcoal canisters have been used for radon measurements for over 40 years. This method is sensitive to temperature, changing radon concentrations, humidity and other parameters, but a comprehensive study dealing with the influence quantities and measurement uncertainty was not available in literature. In this paper, all the identified influence quantities are discussed in detail, uncertainty budget is developed, good practice and bad practice examples are introduced and new recommendations are proposed to optimize the method and reduce uncertainty.

An internal consistency test of the calculation of coincidence-summing correction factors FC for volume sources is presented. The test is based on exact equations relating the values of FC calculated for three ideal measurement configurations. The test is applied to a number of 33 sets of FC values sent by 21 teams. Most sets passed the test, but not the results obtained using the quasi-point source approximation; in the latter case the test qualitatively indicated the magnitude of the bias of FC. © 2019 Elsevier Ltd

A method is presented for calculating the expected number of counts in peaks that have a large relative peak area uncertainty and appear in measured gamma-ray spectra. The method was applied to calculations of the correction factors for peaks occurring in the spectra of radon daughters. It was shown that the factors used for correcting the calculated peak areas to their expected values decrease with an increasing relative peak-area uncertainty. The accuracy of taking the systematic influence inducing the correction factors into account is given by the dispersion of the correction factors corresponding to specific peaks. It was shown that the highest accuracy is obtained in the peak analyses with the GammaVision and Gamma-W software.

In this article, the X-ray and gamma-ray coincidence summing effect in Eu-152 is studied. Coincidence summing corrections and peak and total efficiencies of point and volume sources were determined using the direct matrices multiplication (DMM) method. The theoretically evaluated peak count rates were found to be in good agreement with the experimentally obtained values. Validation was performed by comparing the calculated efficiency curves and the corresponding correction factors with the results obtained using GESPECOR 4.2 software. (C) 2015 Elsevier Ltd. All rights reserved.

Coal as fossil fuel mainly contains naturally occurring radionuclides from the uranium and thorium series and K-40. Use of coal, primarily in industry, as a result has dispersion of radioactive material from coal in and through air and water. The aim of this study was to determine the activity concentrations of natural radionuclides in coal samples from open pit mines Kolubara and to evaluate its effect on population health. The results showed that all measured and calculated values were below the limits recommended in international legislation. (c) 2013 Elsevier Ltd. All rights reserved.

In order to assure Quality Control in accordance with ISO/IEC 17025, it was important, from metrological point of view, to examine the long-term stability of calibration standards previously prepared. Comprehensive reconsideration on efficiency curves with respect to the ageing of calibration standards is presented in this paper. The calibration standards were re-used after a period of 5 years and analysis of the results showed discrepancies in efficiency values. (C) 2012 Elsevier Ltd. All rights reserved.

A study of coincidence summing of X- and gamma rays of Se-75 has been presented in this paper. The computation of the Se-75 spectra was performed by application of the previously published theory by Novkovi et al. The method enables the treatment of all possible single and sum peaks of Se-75. The calculation gave the 419 decay path outcomes, resulting in 84 peak count rate equations and also the total count rate equation. By HPGe spectrometers with 15% and 18% relative efficiency, 20 and 30 peaks were recorded, respectively. Some simplification of the decay scheme was introduced and existing metastable level had to be treated separately. Nevertheless, the experimental values of the peak count rates were in good agreement with the theoretical evaluation. (C) 2011 Elsevier Ltd. All rights reserved.

The direct measurement of the activities of Co-57 sources by application of the sum-peak method recently developed by Novkovic et al., is described in this paper. The comprehensive assessment of the uncertainty budget of the activity of the measured sources has been analyzed. The presented method is successfully tested using an HPGe spectrometer with efficiencies of 50%. The accuracy of this method is confirmed to be comparable with the commonly used methods of the activity measurement of Co-57. (C) 2012 Elsevier Ltd. All rights reserved.

The second part of an intercomparison of the coincidence summing correction methods is presented. This exercise concerned three volume sources, filled with liquid radioactive solution. The same experimental spectra, decay scheme and photon emission intensities were used by all the participants. The results were expressed as coincidence summing corrective factors for several energies of Eu-152 and Cs-134, and different source-to-detector distances. They are presented and discussed. (C) 2012 Elsevier Ltd. All rights reserved.

A simple and efficient method for determination of uranium content in surface soil samples contaminated with depleted uranium, by gamma ray spectrometry is presented. The content of natural uranium and depleted uranium, as well as the activity ratio (235)U/(238)U of depleted uranium, were determined in contaminated surface soil samples by application of this method (C) 2009 Elsevier Ltd All rights reserved

The main scope of this paper is to point out the importance of introducing radon and thoron exhalation measurements from building materials in the regulating frame. Currently (2009), such a regulation of this kind of exposure is not explicitly included in the Serbian regulating network. To this end, this work reports concentration measurements of Ra-226, Th-232 and K-40 and radon and thoron exhalation rates from building materials used in Serbia. Following detailed analysis, it was noticed that both internal exposures to radon and/or thoron exhaling from building materials may exceed external exposures to their precursors contained therein. (C) 2009 Elsevier Ltd. All rights reserved.

A review of the calibration procedures of the semiconductor HPGe spectrometer is presented in this paper. Calibration standards were prepared using the standardized radioactive solution of the common monoenergetic radionuclides mixture and standardized multigamma Eu-152 solution. The matrix materials were spiked using the activated carbon, and homogenized mechanically or by suspension in C2H5OH. Experimentally determined efficiency curves were compared with those obtained by Monte Carlo simulation. (C) 2008 Elsevier Ltd. All rights reserved.

The surface air activity concentration of Pu-241 for the period May 01-15, 1986, for a monitoring site in Vin a, Belgrade was retrospectively estimated. The results were obtained by re-measurement of plutonium fraction alpha-spectrometric sources, with 236 Pu as a tracer, used almost 13 years earlier for the determination of Pu-239,Pu-240 concentration in surface air immediately after the Chernobyl accident. The estimated Pu-241 concentration, based on the Am-241 in-growth method for air samples, ranged from 240 to 7800 mu Bq/m(3). The average activity ratio Pu-241/Pu-239.240 originating from the Chernobyl accident at Belgrade site was approximately 100 at the collection time. (c) 2006 Elsevier Ltd. All rights reserved.