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Air kerma length product and air kerma area product are special quantities used in diagnostic radiology. They are measured using special measurement devices – CT-chambers and KAP-meters, in order to calculate quantities related to patient exposure. Appropriate calibration of all measurement devices is of vital importance, and comparisons between calibration laboratories are necessary to prove competence. It is usually considered adequate to participate in air kerma comparisons to prove capabilities for special quantities, but the literature shows that some problems in calibration procedure can remain unknown. The comparisons directly in terms of special quantities provide additional burden to laboratories, and require special transfer instruments, but they allow checking the whole calibration procedures. This paper describes a comparison between two calibration laboratories in terms of both air kerma length product and air kerma area product. Both laboratories achieved good results for all radiation qualities, considering the measurement uncertainty. Transfer instruments’ linearity, field size dependence and energy dependence were investigated. Even though the metrological properties of the transfer instruments are worse than the ionization chambers, they can be taken into account by introducing additional measurement uncertainty, performing appropriate corrections or choosing calibration points for the comparison for the values of influence quantities where the transfer instrument response is relatively flat. These comparisons provide additional value to calibration laboratories, but there are still several challenges related to their organization and execution.

Quality control and assurance of mammography X-ray generators include usage of solid-state detectors and/or ionization chambers which are calibrated in standard reference radiation fields. IEC 61267:2005 standard defines reference mammography radiation fields for Mo/Mo anode/filtration, while various anode/filtration combinations are encountered in clinical mammography X-ray units. Not all Secondary Standard Dosimetry Laboratories have an X-ray generator with Mo/Mo radiation setup, thus traceability can be established only for the available anode/filter combinations which is commonly limited to W/Al. In this study, W/Al radiation fields were established under laboratory conditions by performing half-value layer measurements, and characterization of four solid-state detectors was performed. X-ray multimeter performance was evaluated in terms of energy response in the W/Al radiation fields. In the laboratory conditions the energy response of the dosimeters had larger deviation from unity for dosimeters without appropriate anode/filter combination selected in the software settings, even though most of the dosimeters had uniform relative response. Discrepancy in the response was further investigated by examining its variation induced by available detector software settings, and it was determined that the dosimeter response can vary up to 20 %. In clinical setup, half-value layer was determined, and detector performance was examined. Dosimeters were tested in clinical fields with Mo/Mo, Mo/Rh, W/Rh, W/Ag anode/filter combinations in the X-ray tube voltage range from 25 kV to 35 kV. For most clinical radiation fields, multi-element detectors had energy response deviation within ±5 %. The single-element detector had one software setting available and has exhibited strong energy dependence. Extensive testing of detector response such as presented in this paper allows for correction factor interpolation based on half-value layer.

According to standard delocalized kinetic models of thermoluminescence (TL), when an irradiated sample is held at a high temperature T, the isothermal TL signal will decay with a characteristic thermal decay constant A which depends strongly on the temperature T. This prediction of standard delocalized kinetic theory is investigated in this paper by studying two TL dosimeters, MgB4O7:Dy, Na and LiB4O7:Cu, In (hereafter MBO and LBO correspondingly). In the case of LBO it was found that the thermal decay constant A of the main dosimetric TL peak follows exactly the predictions of standard delocalized kinetic theory. Furthermore, the thermal activation energy of the main peak evaluated by the isothermal decay method is in full agreement with values obtained from initial rise and glow curve fitting methods. However, in the case of MBO it was found that the thermal decay constant A varies little with the isothermal decay temperature T. In order to explain these unusual results for MBO, the TL glow curves and isothermal decay curves were analyzed using analytical expressions derived recently from a radiative tunneling recombination model. Based on the different behavior of the two TL dosimeters, it is suggested that the isothermal decay of TL at high temperatures can be used to discriminate between radiative delocalized recombination and radiative localized recombination processes. (C) 2015 Elsevier Ltd. All rights reserved.

According to standard delocalized kinetic models of thermoluminescence (TL), when an irradiated sample is held at a high temperature T, the isothermal TL signal will decay with a characteristic thermal decay constant A which depends strongly on the temperature T. This prediction of standard delocalized kinetic theory is investigated in this paper by studying two TL dosimeters, MgB4O7:Dy, Na and LiB4O7:Cu, In (hereafter MBO and LBO correspondingly). In the case of LBO it was found that the thermal decay constant A of the main dosimetric TL peak follows exactly the predictions of standard delocalized kinetic theory. Furthermore, the thermal activation energy of the main peak evaluated by the isothermal decay method is in full agreement with values obtained from initial rise and glow curve fitting methods. However, in the case of MBO it was found that the thermal decay constant A varies little with the isothermal decay temperature T. In order to explain these unusual results for MBO, the TL glow curves and isothermal decay curves were analyzed using analytical expressions derived recently from a radiative tunneling recombination model. Based on the different behavior of the two TL dosimeters, it is suggested that the isothermal decay of TL at high temperatures can be used to discriminate between radiative delocalized recombination and radiative localized recombination processes. (C) 2015 Elsevier Ltd. All rights reserved.

The paper deals with the results of the investigations of indoor radon measurements in more than 300 rural and urban dwellings in Kosovo and Metohija. All measurements were carried out using CR-39 solid State nuclear track detectors by similar protocols and within two series in 1990-s and in 2000-s, in 34 settlements divided by 9 regions, thus covering significant part of Kosovo. For most of measured points the adjustment for seasonal variation was necessary and had been conducted. Highest average values of indoor radon concentrations were found in rural settlements of Lipljan and Vitina regions, 512 and 452 Bq/m(3), respectively. Combined analysis allows indoor radon concentration of 220 Bq/m(3) to be suggested as representative estimate for Kosovo, while additional data appear. Observed pattern of indoor radon seasonal variation and difference of radon levels between ground and upper floors suggest soil radon as primary source of indoor radon and significance of convection type radon entry. (C) 2010 Elsevier Ltd. All rights reserved.

This paper presents the results of the seasonal indoor radon concentration measurements in dwellings in all regions of the Former Yugoslav Republic (FYR) of Macedonia. The measurements were made in 437 dwellings using CR-39 track detectors over four successive three-month periods (winter, spring, summer and autumn) throughout 2009. The results of analysis of variance showed statistically significant differences between indoor radon concentrations in different seasons. The geometric mean values and geometric standard deviations of indoor radon concentrations in winter, spring, summer and autumn were obtained to be: 115 Bq m(-3) (2.02), 72 Bq m(-3) (1.97), 46 Bq m(-3) (1.95), 92 Bq m(-3) (2.02), respectively. The geometric mean values of spring, summer and autumn to winter ratios were found to be: 0.63 (1.50), 0.40 (1.81), and 0.80 (1.58), respectively. The results of the analysis of the variance showed statistically significant differences among the indoor radon measurements for the regions in different seasons. The influence of the factors linked to building characteristics in relation to radon measurements in different seasons was examined. The factors which enable a differentiation into subgroups (significance level p LT 0.05) are the floor level, basement and building materials. (C) 2011 Elsevier Ltd. All rights reserved.

The paper deals with the results of the investigations of indoor radon measurements in more than 300 rural and urban dwellings in Kosovo and Metohija. All measurements were carried out using CR-39 solid State nuclear track detectors by similar protocols and within two series in 1990-s and in 2000-s, in 34 settlements divided by 9 regions, thus covering significant part of Kosovo. For most of measured points the adjustment for seasonal variation was necessary and had been conducted. Highest average values of indoor radon concentrations were found in rural settlements of Lipljan and Vitina regions, 512 and 452 Bq/m(3), respectively. Combined analysis allows indoor radon concentration of 220 Bq/m(3) to be suggested as representative estimate for Kosovo, while additional data appear. Observed pattern of indoor radon seasonal variation and difference of radon levels between ground and upper floors suggest soil radon as primary source of indoor radon and significance of convection type radon entry. (C) 2010 Elsevier Ltd. All rights reserved.

This paper presents the results of the seasonal indoor radon concentration measurements in dwellings in all regions of the Former Yugoslav Republic (FYR) of Macedonia. The measurements were made in 437 dwellings using CR-39 track detectors over four successive three-month periods (winter, spring, summer and autumn) throughout 2009. The results of analysis of variance showed statistically significant differences between indoor radon concentrations in different seasons. The geometric mean values and geometric standard deviations of indoor radon concentrations in winter, spring, summer and autumn were obtained to be: 115 Bq m(-3) (2.02), 72 Bq m(-3) (1.97), 46 Bq m(-3) (1.95), 92 Bq m(-3) (2.02), respectively. The geometric mean values of spring, summer and autumn to winter ratios were found to be: 0.63 (1.50), 0.40 (1.81), and 0.80 (1.58), respectively. The results of the analysis of the variance showed statistically significant differences among the indoor radon measurements for the regions in different seasons. The influence of the factors linked to building characteristics in relation to radon measurements in different seasons was examined. The factors which enable a differentiation into subgroups (significance level p LT 0.05) are the floor level, basement and building materials. (C) 2011 Elsevier Ltd. All rights reserved.

This paper deals with the results of indoor radon and thoron concentrations and exposure doses obtained for 63 dwellings out of the 14 rural communities of Central Kosovo, North Kosovo and Prizren region. These research activities are part of overall radiological research that has systematically been carried out since 1986, particularly in Kosovo and Metohija regions. Passive radon/thoron discriminative detectors, exposed for three months, were used. The arithmetic mean concentrations of indoor radon and thoron are C(Rn) = 429 Bq m(-3) C(Tn) = 85 Bq m(-3). (C) 2009 Elsevier Ltd. All rights reserved.

This paper deals with the results of indoor radon and thoron concentrations and exposure doses obtained for 63 dwellings out of the 14 rural communities of Central Kosovo, North Kosovo and Prizren region. These research activities are part of overall radiological research that has systematically been carried out since 1986, particularly in Kosovo and Metohija regions. Passive radon/thoron discriminative detectors, exposed for three months, were used. The arithmetic mean concentrations of indoor radon and thoron are C(Rn) = 429 Bq m(-3) C(Tn) = 85 Bq m(-3). (C) 2009 Elsevier Ltd. All rights reserved.

This paper presents the main dosimetric characteristics of newly prepared, complete tissue-equivalent thermoluminescent detectors, Li2B4O7 :Cu,In,Ag and Li2B4O7:Cu,In in form of sintered pellets, developed at the Institute of Nuclear Sciences, Vinca. (C) 2001 Elsevier Science Ltd. All rights reserved.

This paper presents the main dosimetric characteristics of newly prepared, complete tissue-equivalent thermoluminescent detectors, Li2B4O7 :Cu,In,Ag and Li2B4O7:Cu,In in form of sintered pellets, developed at the Institute of Nuclear Sciences, Vinca. (C) 2001 Elsevier Science Ltd. All rights reserved.