First international intercomparison of luminescence techniques using samples from the Techa River Valley.

GSF-National Research Centre for Environment and Health, Germany.
Health Physics (Impact Factor: 0.77). 02/2002; 82(1):94-101. DOI: 10.1097/00004032-200201000-00012
Source: PubMed

ABSTRACT Bricks collected from a contaminated village (Muslyumovo) of the lower Techa river valley, Southern Urals, Russia, were measured using thermoluminescence and optically stimulated luminescence by four European laboratories and a U.S. laboratory to establish and compare the applied dose reconstruction methodologies. The bricks, collected from 60-100-year-old buildings, had accumulated a relatively high dose due to natural sources of radiation in the brick and from the surrounding environment. This work represents the results of a first international intercomparison of luminescence measurements for bricks from the Southern Urals. The luminescence measurements of absorbed dose in bricks collected from the most shielded locations of the same buildings were used to determine the background dose due to natural sources of radiation and to validate the age of the bricks. The absorbed dose in different bricks measured by four laboratories using thermoluminescence and optically stimulated luminescence at a depth of 10 +/- 2.5 mm from the exposed brick surface agreed within +/-21%. After subtraction of the natural background dose, the absorbed dose in brick due to contaminated river sediments and banks was calculated and found to range between 150 and 200 mGy. The cumulative doses in brick due to man-made sources of radiation at 100 and 130 mm depths in the bricks were also measured and found to be consistent with depth dose profiles calculated by Monte Carlo simulations of photon transport for possible source distributions.

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    ABSTRACT: The potential of the 210°C Thermoluminescence (TL) peak in quartz for accurate dose reconstruction is studied by comparative TL and optically simulated luminescence (OSL) measurements on quartz extracted from bricks from a mill in a contaminated village of the Techa River valley, Southern Urals, Russia. The cumulative doses measured with TL were found to be continuously lower (on average 10–20%) than the ones measured with OSL for the same sample and using the same luminescence reader. From dose recovery tests, laboratory kinetic analysis and available meteorological parameters of the sample site for the past 100 years, it is concluded that the most likely reason for the discrepancy is thermal fading of the 210°C TL peak. By applying a suitable model, an effective lifetime of the electron trap of the 210°C TL peak of 200–700 years is estimated for the moderate continental climate at the sample site. It is concluded that for samples in regions of continental climate and directly exposed to sunlight, dose measurements using the 210°C TL peak should be restricted to the last 50–60 years. Applications to older samples should only be considered if bricks are not directly exposed to sunlight or if the background dose is small compared to the anthropogenic dose, as the latter will have been acquired during shorter times and will thus not have been subjected to significant thermal fading.
    Radiation Measurements 05/2011; 46(5):485-493. DOI:10.1016/j.radmeas.2011.03.019 · 1.14 Impact Factor
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    ABSTRACT: The requirements for biodosimetric techniques used at long times after exposure, i.e., 6 months to more than 50 years, are unique compared to the requirements for methods used for immediate dose estimation. In addition to the fundamental requirement that the assay measures a physical or biologic change that is proportional to the energy absorbed, the signal must be highly stable over time to enable reasonably precise determinations of the absorbed dose decades later. The primary uses of these biodosimetric methods have been to support long-term health risk (epidemiologic) studies or to support compensation (damage) claims. For these reasons, the methods must be capable of estimating individual doses, rather than group mean doses. Even when individual dose estimates can be obtained, inter-individual variability remains as one of the most difficult problems in using biodosimetry measurements to rigorously quantify individual exposures. Other important criteria for biodosimetry methods include obtaining samples with minimal invasiveness, low detection limits, and high precision. Cost and other practical limitations generally prohibit biodosimetry measurements on a large enough sample to replace analytical dose reconstruction in epidemiologic investigations. However, these measurements can be extremely valuable as a means to corroborate analytical or model-based dose estimates, to help reduce uncertainty in individual doses estimated by other methods and techniques, and to assess bias in dose reconstruction models. There has been extensive use of three biodosimetric techniques in irradiated populations: EPR (using tooth enamel), FISH (using blood lymphocytes), and GPA (also using blood); these methods have been supplemented with luminescent methods applied to building materials and artifacts. A large number of investigations have used biodosimetric methods many years after external and, to a lesser extent, internal exposure to reconstruct doses received from accidents, from occupational exposures, from environmental releases of radioactive materials, and from medical exposures. In most applications, the intent has been to either identify highly exposed persons or confirmed suspected exposures. Improvements in methodology, however, have led many investigators to attempt quantification of whole-body doses received, or in a few instances, to estimate organ doses. There will be a continued need for new and improved biodosimetric techniques not only to assist in future epidemiologic investigations but to help evaluate the long-term consequences following nuclear accidents or events of radiologic terrorism.
    Radiation Measurements 07/2007; DOI:10.1016/j.radmeas.2007.05.036 · 1.14 Impact Factor
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    ABSTRACT: Optically stimulated luminescence (OSL) dosimetry is applied to quartz extracted from bricks from a mill in a contaminated village (Muslyumovo) of the Techa River valley, Southern Urals, Russia, for the purpose of dose reconstruction. Previous works [Göksu et al., 2002. First international intercomparison of luminescence techniques using samples from the Techa river valley. Health Phys. 82, 94–101] have shown that the expected dose due to man-made sources of radiation in the bricks is in the same range as the background dose due to natural sources of radiation, therefore a precise estimate of the cumulative and background dose is of utmost importance. Cumulative doses could be assessed with OSL with a precision of around 4% and lie between 450 and 600 mGy. The background dose was carefully determined by a combination of laboratory measurements, in-situ gamma spectrometry and Monte Carlo modelling. The results show that the gamma-dose rate of the soil was overestimated and the fractional brick gamma-dose rate underestimated in previous studies, but that the overall gamma-dose rate was nearly correct, due to mutual compensation. The obtained anthropogenic doses in brick measured with OSL lie between 200 and 300 mGy, show variability between adjacent bricks within error limits for one spot but a significant difference for two samples is observed for another spot. A distinct dependency of measured dose upon sample height is observed, which is an indication of a source distribution, which extends over a large area and up to a certain depth into the soil and in which higher contaminated areas are located at a greater distance to the mill than lower contaminated areas. A measured dose–depth profile is compared with previously published Monte Carlo calculations to verify the source energy.
    Radiation Measurements 03/2011; 46(3):277-285. DOI:10.1016/j.radmeas.2010.06.028 · 1.14 Impact Factor

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