| 1. |
- Ainsbury, Elizabeth, et al.
(author)
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Integration of new biological and physical retrospective dosimetry methods into EU emergency response plans - joint RENEB and EURADOS inter-laboratory comparisons
- 2017
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In: International Journal of Radiation Biology. - : Informa UK Limited. - 0955-3002 .- 1362-3095. ; 93:1, s. 99-109
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Journal article (peer-reviewed)abstract
- Purpose: RENEB, 'Realising the European Network of Biodosimetry and Physical Retrospective Dosimetry,' is a network for research and emergency response mutual assistance in biodosimetry within the EU. Within this extremely active network, a number of new dosimetry methods have recently been proposed or developed. There is a requirement to test and/or validate these candidate techniques and inter-comparison exercises are a well-established method for such validation. Materials and methods: The authors present details of inter-comparisons of four such new methods: dicentric chromosome analysis including telomere and centromere staining; the gene expression assay carried out in whole blood; Raman spectroscopy on blood lymphocytes, and detection of radiation induced thermoluminescent signals in glass screens taken from mobile phones. Results: In general the results show good agreement between the laboratories and methods within the expected levels of uncertainty, and thus demonstrate that there is a lot of potential for each of the candidate techniques. Conclusions: Further work is required before the new methods can be included within the suite of reliable dosimetry methods for use by RENEB partners and others in routine and emergency response scenarios.
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| 2. |
- Ask, Maria, et al.
(author)
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Detection of borehole breakouts at the Forsmark site, Sweden
- 2006
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In: In-situ rock stress. - London : Taylor and Francis Group. - 041540097X ; , s. 79-86
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Conference paper (peer-reviewed)abstract
- The objective of this paper was to investigate if borehole breakouts exist at the Forsmark investigation site of the Swedish Nuclear Fuel and Waste Management Co. Breakouts generally form when the stress concentration around the borehole exceeds the rock strength of the borehole wall, and result in borehole failure in the direction parallel to the minimum horizontal stress in vertical boreholes. Borehole televiewer and borehole image processing system data in boreholes KFM01A and KFM01B have been analyzed. The analyzes reveal that breakouts appear over 30-40% of the length of the investigated boreholes. The breakouts appear with both shallow- and deep-failure depths, where the overwhelming majority is of the shallow failure type. The scope of this initial study does not include the full characterization of identified breakouts and it is not clear at this stage as to the origin of the breakouts, i.e. if they are stress and/or drilling induced
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| 3. |
- Bernhardsson, Christian, et al.
(author)
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Assessment of effective dose to an individual carrying materials useful for radiation dosimetry by optically stimulated luminescence
- 2015
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In: Medical Physics in the Baltic States : Proceedings of the 12th International Conference on Medical Physics - Proceedings of the 12th International Conference on Medical Physics. - 1822-5721. ; , s. 48-51
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Conference paper (peer-reviewed)abstract
- Optically stimulated luminescence (OSL) from ordinary household salt has proven high potential for very low dose retrospective dosimetry. In the present paper other common place materials are considered and their dosimetric OSL-properties compared with household salt. The potential for assessment of the effective dose to an individual carrying such materials is investigated.
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| 4. |
- Bernhardsson, Christian, et al.
(author)
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Household salt as a retrospective dosemeter using optically stimulated luminescence.
- 2009
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In: Radiation and Environmental Biophysics. - : Springer Science and Business Media LLC. - 1432-2099 .- 0301-634X. ; 48, s. 21-28
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Journal article (peer-reviewed)abstract
- The aim of this work was to investigate the potential of a selection of household salts (NaCl) as a retrospective dosemeter for ionising radiation using optically stimulated luminescence (OSL). The OSL-response of five brands of salt to an absorbed dose in the range from 1 mGy to 9 Gy was investigated using a Risø TL/OSL-15 reader and a (60)Co beam, allowing low dose-rate irradiations. The salt was optically stimulated with blue light (lambda = 470 +/- 30 nm) at a constant stimulation power (CW-OSL) of 20 mW cm(-2). A linear dose response relationship was found in the dose range from 1 mGy to about 100 mGy and above that level, the relationship becomes moderately supra-linear, at least up to 9 Gy. Depending on the sensitivity and background signal, the minimum detectable absorbed dose (MDD) for the household salt when kept at sealed conditions varied from 0.2 to 1.0 mGy, for the household salts investigated. In addition to its widespread abundance and availability, the low MDD suggests that household salt should seriously be considered as an emergency dosemeter. However, the OSL-properties of NaCl under normal household usage need to be more properly investigated as well as the variation in sensitivity by the quality of the radiation. A further optimisation of the read-out sequence for various brands of commercially available salt may further improve the sensitivity, in terms of luminescence yield, and the signal reproducibility.
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| 5. |
- Bernhardsson, Christian, et al.
(author)
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OSL in Household Salt (NaCl) for Environmental, Occupational and Medical Dosimetry
- 2009
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In: Medical Physics In The Baltic States: Proceedings Of The 7th International Conference On Medical Physics. - 1822-5721. ; , s. 65-68
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Conference paper (peer-reviewed)abstract
- The recent progress in our work to implement salt (NaCl) as a dosemeter is presented. Laboratory investigations have indicated a linear dose response from 1 mGy to about 100 mGy and detection limits down to 0.1 mGy. Investigations in the clinic comparing TL-dosimetry in LiF and OSL in NaCl have indicated a similar dose response for the two dosemeters at different photon energies. Field studies with stationary dosemeter kits containing TLDs (LiF) and NaCl suggests that salt is also a good candidate for environmental monitoring of radiation.
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| 6. |
- Christiansson, Maria
(author)
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Household salt as an emergency radiation dosemeter for retrospective dose assessments using optically stimulated luminescence
- 2014
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Doctoral thesis (other academic/artistic)abstract
- In the event of a radiation accident, it is crucial to make rapid estimates of the absorbed dose received by both emergency workers, so-called first responders, and members of the public. Today, only personnel in rescue teams responding to nuclear emergencies have access to individual dosemeters. To make accurate assessments of the radiological consequences of an emergency situation, methods of retrospectively determining the absorbed dose to individuals and groups of people are needed. The use of optically stimulated luminescence (OSL) in crystalline materials has been considered for retrospective dose assessment after radiation accidents during the past decade. The purpose of this work was to investigate the potential of household salt as a retrospective dosemeter for ionizing radiation using OSL. Measurements of the OSL output as a function of stimulation power, powering mode, preheating temperature, etc., have been performed, and the OSL readout sequence was optimized for salt. Furthermore, the possibility of developing a low-dose (<100 mGy) OSL readout protocol, to be employed with household salt, has been investigated, as have the signal stability and signal preservation in salt in the original salt containers. The OSL response of household salt to different photon energies has also been studied, and compared with the response in tissue-equivalent material. The investigated kinds of household salt, both sea-salt, recrystallized mine salt and non dissolved mine salt, exhibited promising dosimetric properties for low-dose applications, showing a linear dose response in the interval 1-100 mGy, and detection limits down to about 0.2 mGy. A standard SAR protocol for measuring household salt using a Risø TL/OSL-DA-15 reader for low doses was developed. This protocol was found to recover the administered dose within 10% for doses between 1 and 250 mGy for the kind of household salt most extensively studied here, and within 20% for the other three kinds. The OSL signal in household salt when stimulated with blue LEDs did not fade during storage for up to 142 days, but increased slowly during storage. Studies of different packages showed that salt in white plastic packages (although appearing opaque) showed almost complete signal loss due to optical bleaching, both in the laboratory and during field trials in a village contaminated by the Chernobyl accident. The signal appeared to be preserved for several months in salt in other types of packages, e.g. cardboard. The results of measurements using salt as a personal dosemeter in Fukushima, Japan, following the nuclear power plant accident, and in small salt containers in a village contaminated by the Chernobyl accident showed that doses as low as 100 μGy can be assessed. However, measurements of the OSL in NaCl gave a higher absorbed dose than the more tissue-equivalent TL-LiF dosemeter at lower photon energies (<300 keV). The absorbed doses obtain from OSL in NaCl require an energy-dependent conversion factor for photon energies below 600 keV. Hence, knowledge on the average photon energy at the accident site will improve the accuracy of dose estimates when using NaCl as a retrospective dosemeter.
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| 7. |
- Christiansson, Maria, et al.
(author)
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Household salt for retrospective dose assessments using OSL: signal integrity and its dependence on containment, sample collection, and signal readout.
- 2014
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In: Radiation and Environmental Biophysics. - : Springer Science and Business Media LLC. - 1432-2099 .- 0301-634X. ; 53:3, s. 559-569
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Journal article (peer-reviewed)abstract
- The aim of this work was to determine how a latent optically stimulated luminescence (OSL) signal in irradiated household salt is preserved under various ambient conditions, from the time of exposure to the time of signal readout. The following parameters were examined: optical fading in fluorescent light and under darkroom conditions (red light), thermal stability of the OSL signal during storage in a light-tight container, optical fading in representative container types, and sensitization effects of the OSL signal in exposed household salt. Furthermore, the influence of grain mixing within the saltshaker or salt container was studied by determining the dose gradient within typical salt packages. Finally, the signal integrity of salt irradiated under field conditions in a village in Belarus contaminated by Chernobyl fallout was investigated. The results show that the OSL signal in household salt is preserved in large cardboard box containers, but not in white plastic salt containers or in small portion bags used in, e.g., fast food restaurants. Furthermore, the continuous wave blue OSL signal in household salt does not fade significantly during storage up to 140 days. On the contrary, the signal appears to slowly increase during storage ("inverse fading"). Field tests of two different salt containers (with and without black tape to block light) located in Belarussian households confirmed that the signal is preserved in white plastic salt containers when they are covered with extra light-shielding material.
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| 8. |
- Christiansson, Maria, et al.
(author)
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Optimizing A Readout Protocol For Low Dose Retrospective Osl-Dosimetry Using Household Salt
- 2012
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In: Health Physics. - 1538-5159. ; 102:6, s. 631-636
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Journal article (peer-reviewed)abstract
- The authors' aim has been to find a single aliquot regenerative dose (SAR) protocol that accurately recovers an unknown absorbed dose in the region between 1-250 mGy in household salt. The main investigation has been conducted on a specific mine salt (>98.5% NaCl) intended for household use, using optical stimulation by blue LED (lambda = 462 nm). The most accurate dose recovery for this brand of salt is found to be achieved when using Peak Signal Summing (PSS) of the OSL-decay and a preheat temperature of 200 degrees C after the test dose. A SAR protocol for the household salt with preset values of regenerative doses (R1-R5) and a test dose (TED) of 17 mGy is also suggested here. Under laboratory conditions, the suggested protocol recovers unknown absorbed doses in this particular brand within 5% (2 SD) in the dose range between 1-250 mGy. This is a very promising result for low dose applications of household salt as a retrospective dosimeter after a nuclear or radiological event. Health Phys. 102(6):631-636;2012
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| 9. |
- Christiansson, Maria, et al.
(author)
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OSL in NaCl vs. TL in LiF for absorbed dose measurements and radiation quality assessment in the photon energy range 20 keV to 1.3 MeV
- 2018
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In: Radiation Measurements. - : Elsevier BV. - 1350-4487. ; 112, s. 11-15
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Journal article (peer-reviewed)abstract
- The aim of this study was to determine the photon energy dependence of absorbed dose measurements, in a comparison of optically stimulated luminescence (OSL) in NaCl with thermoluminescence (TL) in LiF:Mg,Cu,P. The comparisons were made at exposure to ionizing radiation in the photon energy range 20 keV to 1.3 MeV. Specially designed dosemeter kits containing both NaCl and LiF were used under i) laboratory conditions using defined radiation fields, ii) laboratory conditions using sealed point sources mimicking unintentional exposures, and iii) field conditions in areas in Japan that were affected by the Fukushima Daiichi nuclear disaster in 2011. The dosemeter kits used in Japan showed that absorbed doses as low as 100 μGy can be assessed from the OSL signal in NaCl. The ratio of the dosemeter readings using OSL in NaCl and TL in LiF increases after irradiation at lower photon energies (less than a few hundred keV) as determined under laboratory conditions. Compensating for this energy dependence of the absorbed dose determinations obtained from OSL in NaCl would thus require an energy-dependent conversion factor for photon energies below 600 keV. On the other hand, the difference in the photon energy dependence between NaCl and LiF may be used to assess the mean effective energy of the photon field. The signal ratios between NaCl and LiF after exposure to radiation in the Fukushima Dashii contaminated areas in Japan, 1.67 ± 0.26 (2013) and 1.63 ± 0.32 (2015), indicate that the mean photon energy in this area was 300–400 keV during the years of the survey.
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| 10. |
- Christiansson, Maria, et al.
(author)
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USING AN OPTIMISED OSL SINGLE-ALIQUOT REGENERATIVE-DOSE PROTOCOL FOR LOW-DOSE RETROSPECTIVE DOSIMETRY ON HOUSEHOLD SALT.
- 2011
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In: Radiation Protection Dosimetry. - : Oxford University Press (OUP). - 1742-3406 .- 0144-8420. ; 144, s. 584-587
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Journal article (peer-reviewed)abstract
- The single-aliquot regenerative-dose (SAR) protocols used in retrospective dosimetry for optically stimulated luminescence measurements have been mainly developed for archaeological and geological dating of quartz and feldspar. The aim in this study is to find a read-out protocol that can generate the most reproducible signal for household salt (NaCl) at absorbed doses below 100 mGy. The relation between the reproducibility of the signal, in terms of the ratio between given absorbed dose and SAR-calculated dose, and parameters such as test-dose pre-heat temperature has been studied. It was found that a temperature of 200°C yielded the best reproducibility in the SAR-calculated dose, which is a somewhat higher pre-heat temperature than what is used for dating of quartz.
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