| 1. |
- Bassinet, C., et al.
(författare)
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Retrospective radiation dosimetry using OSL of electronic components: Results of an inter-laboratory comparison
- 2014
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Ingår i: Radiation Measurements. - : Elsevier BV. - 1879-0925 .- 1350-4487. ; 71, s. 475-479
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Tidskriftsartikel (refereegranskat)abstract
- In the framework of the EU-FP7 MULTIBIODOSE project, two protocols using OSL of resistors removed from the circuit board of mobile phones were developed with the aim to use the resistors as fortuitous dosimeters in the event of a large scale radiological accident. This paper presents the results of an inter-laboratory comparison carried out under the umbrella of EURADOS. The two aims of this exercise were the validation of the MULTIBIODOSE protocols by a large number of laboratories and the dissemination of the method with the objective of preparing the basis for a network that could increase Europe's response capacity in the case of a mass casualty radiological emergency. Twelve institutes from eleven European countries and one institute from the USA, with various degrees of expertise in OSL dosimetry, took part in the OSL inter-laboratory comparison. Generally, a good agreement within uncertainties was observed between estimated and nominal doses. (C) 2014 Elsevier Ltd. All rights reserved.
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| 2. |
- Bernhardsson, Christian, et al.
(författare)
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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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Ingår i: 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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Konferensbidrag (refereegranskat)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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| 3. |
- Christiansson, Maria, et al.
(författare)
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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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Ingår i: Radiation and Environmental Biophysics. - : Springer Science and Business Media LLC. - 1432-2099 .- 0301-634X. ; 53:3, s. 559-569
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Tidskriftsartikel (refereegranskat)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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| 4. |
- Christiansson, Maria, et al.
(författare)
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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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Ingår i: Radiation Measurements. - : Elsevier BV. - 1350-4487. ; 112, s. 11-15
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Tidskriftsartikel (refereegranskat)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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| 5. |
- Geber-Bergstrand, Therése
(författare)
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Optically Stimulated Luminescence for Retrospective Radiation Dosimetry. The Use of Materials Close to Man in Emergency Situations
- 2017
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- If an accident or attack involving radiological or nuclear material were to happen, people from the general public would be at risk of exposure to ionising radiation. Unlike people working with ionising radiation, for whom level of exposure to radiation is constantly monitored with dosemeters, people from the general population do not wear dosemeters; thus, the dose estimations for these individuals must be performed using alternative methods. This field of research is called retrospective dosimetry (or emergency dosimetry) and includes both biological and physical techniques. Following an accident or attack, dose estimations of potentially exposed individuals have to be performed as soon as possible, to give the proper medical care promptly and, especially in the case of a large-scale incident, to use the available resources in the best and most effective manner.In contrast to developing conventional dosemeter material, the approach for research into retrospective dosemeter materials is somewhat reversed. Instead of involving identification (or development) of a material that meets the set requirements, the work needs to conform to the properties of the materials found near or on people. This necessity often means that several materials/techniques are needed to fulfil the same requirements. In addition, exactly which materials will be present in a given situation is never certain, and the addition of new materials/methods that could be used for retrospective dosimetry thus is always a valuable contribution.In this thesis, a number of materials found in the immediate vicinity of people have been investigated with regard to their potential to act as retrospective radiation dosemeters using optically stimulated luminescence (OSL). The materials include human teeth and dental repair materials, components from electronic devices, desiccants, and common household salt (NaCl). The aim is both to increase the number of materials that could be used with OSL and to further develop methods for the materials already known to have some dosimetric properties.The overall conclusion of this work is that several materials found on or in the immediate vicinity of people can be used in retrospective dosimetry using OSL. Also, initial estimations of conversion factors for the transition between the dose to the retrospective dosemeter material and the dose to an individual have been obtained using an anthropomorphic phantom.
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| 6. |
- Geber-Bergstrand, Therése, et al.
(författare)
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Optically stimulated luminescence (OSL) dosimetry in irradiated alumina substrates from mobile phone resistors
- 2018
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Ingår i: Radiation and Environmental Biophysics. - : Springer Science and Business Media LLC. - 0301-634X .- 1432-2099. ; 57:1, s. 69-75
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Tidskriftsartikel (refereegranskat)abstract
- In this study the dosimetric properties of alumina (Al2O3) substrates found in resistors retrieved from mobile phones were investigated. Measurements of the decline of optically stimulated luminescence (OSL) generated following exposure of these substrates to ionising radiation showed that 16% of the signal could still be detected after 2 years (735 days). Further, the magnitude of the regenerative dose (calibration dose; Di) had no impact on the accuracy of dose estimates. Therefore, it is recommended that the Di be set as low as is practicable, so as to accelerate data retrieval. The critical dose, DCL, and dose limit of detection, DDL, taking into account the uncertainty in the dose–response relation as well as the uncertainty in the background signal, was estimated to be 7 and 13 mGy, respectively, 1 h after exposure. It is concluded that given the significant long-term component of fading, an absorbed dose of 0.5 Gy might still be detectable up to 6 years after the exposure. Thus, OSL from alumina substrates can be used for dosimetry for time periods far in excess of those previously thought.
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| 7. |
- Geber, Therese, et al.
(författare)
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Desiccants for retrospective dosimetry using optically stimulated luminescence (OSL)
- 2015
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Ingår i: Radiation Measurements. - : Elsevier BV. - 1879-0925 .- 1350-4487. ; 78, s. 17-22
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Tidskriftsartikel (refereegranskat)abstract
- Optically stimulated luminescence (OSL) was used to test different kinds of desiccants for their potential use in retrospective dosimetry. Desiccants are used for the purpose of absorbing liquids and can be found in a number of items which may be found in the immediate environment of a person, including hand bags, drug packages, and the vehicles of rescue service teams. Any material exhibiting OSL properties suitable for retrospective dosimetry is a useful addition to the existing dosimetry system available in emergency preparedness. Eleven kinds of desiccants were investigated in order to obtain an overview of the fundamental OSL properties necessary for retrospective dosimetry. Measurements were made using a Rise TL/OSL reader and irradiations were achieved with the Sr-90/Y-90 source incorporated in the reader. Several of the desiccants exhibited promising properties as retrospective dosemeters. Some of the materials exhibited a strong as-received signal, i.e. without any laboratory irradiation, but the origin of this signal has not yet been established. The minimum detectable dose ranged from 8 to 450 mGy for ten of the materials and for one material (consisting of natural clay) the minimum detectable dose was 1.8 Gy.
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| 8. |
- Geber, Therese, et al.
(författare)
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Eye lens dosimetry for interventional procedures - Relation between the absorbed dose to the lens and dose at measurement positions
- 2011
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Ingår i: Radiation Measurements. - : Elsevier BV. - 1350-4487 .- 1879-0925. ; 46:11, s. 1248-1251
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Konferensbidrag (refereegranskat)abstract
- This study investigated the relationship between the absorbed dose to the lens of the eye and the absorbed dose at different measurement positions near the eye of interventional radiologists. It also visualised the dose distribution inside the head, both when protective eyewear were used and without such protection. The best position for an eye lens dosimeter was found to be at the side of the head nearest to the radiation source, close to the eye. Positioning the dosimeter at the eyebrow could lead to an underestimation of the lens dose of as much as 45%. The measured dose distribution showed that the absorbed dose to the eye lenses was high compared to the other parts of the head, which stresses the importance of wearing protective eyewear. However, many models of eyewear were found to be deficient as the radiation could slip through at several places, e.g. at the cheek. The relationship between the absorbed dose to the lens and the kerma-area-product (P-KA) delivered to the patient was also studied. (C) 2011 Elsevier Ltd. All rights reserved.
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| 9. |
- Geber, Therese, et al.
(författare)
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Retrospective dosimetry using OSL of tooth enamel and dental repair materials irradiated under wet and dry conditions.
- 2012
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Ingår i: Radiation and Environmental Biophysics. - : Springer Science and Business Media LLC. - 1432-2099 .- 0301-634X. ; 51:4, s. 443-449
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Tidskriftsartikel (refereegranskat)abstract
- Following a radiological or nuclear emergency event, there is a need for quick and reliable dose estimations of potentially exposed people. In situations where dosimeters are not readily available, the dose estimations must be carried out using alternative methods. In the present study, the optically stimulated luminescence (OSL) properties of tooth enamel and different dental repair materials have been examined. Specimens of the materials were exposed to gamma and beta radiation in different types of liquid environments to mimic the actual irradiation situation in the mouth. Measurements were taken using a Risø TL/OSL reader, and irradiations were made using a (90)Sr/(90)Y source and a linear accelerator (6 MV photons). Results show that the OSL signal from tooth enamel decreases substantially when the enamel is kept in a wet environment. Thus, tooth enamel is not reliable for retrospective dose assessment without further studies of the phenomenon. Dental repair materials, on the other hand, do not exhibit the same effect when exposed to liquids. In addition, dose-response and fading measurements of the dental repair materials show promising results, making these materials highly interesting for retrospective dosimetry. The minimum detectable dose for the dental repair materials has been estimated to be 20-185 mGy.
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