| 1. |
- Ainsbury, Elizabeth A., et al.
(författare)
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UNCERTAINTY ON RADIATION DOSES ESTIMATED BY BIOLOGICAL AND RETROSPECTIVE PHYSICAL METHODS
- 2018
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Ingår i: Radiation Protection Dosimetry. - : OXFORD UNIV PRESS. - 0144-8420 .- 1742-3406. ; 178:4, s. 382-404
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Tidskriftsartikel (refereegranskat)abstract
- Biological and physical retrospective dosimetry are recognised as key techniques to provide individual estimates of dose following unplanned exposures to ionising radiation. Whilst there has been a relatively large amount of recent development in the biological and physical procedures, development of statistical analysis techniques has failed to keep pace. The aim of this paper is to review the current state of the art in uncertainty analysis techniques across the EURADOS Working Group 10-Retrospective dosimetry members, to give concrete examples of implementation of the techniques recommended in the international standards, and to further promote the use of Monte Carlo techniques to support characterisation of uncertainties. It is concluded that sufficient techniques are available and in use by most laboratories for acute, whole body exposures to highly penetrating radiation, but further work will be required to ensure that statistical analysis is always wholly sufficient for the more complex exposure scenarios.
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| 2. |
- 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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| 3. |
- 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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| 4. |
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| 5. |
- Majgier, Renata, et al.
(författare)
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OSL PROPERTIES IN VARIOUS FORMS OF KCl AND NaCl SAMPLES AFTER EXPOSURE TO IONIZING RADIATION
- 2019
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Ingår i: Radiation Protection Dosimetry. - : Oxford University Press (OUP). - 1742-3406 .- 0144-8420. ; 184:1, s. 90-97
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this work was to investigate the optically-stimulated luminescence (OSL) properties of potassium chloride (KCl) and its potential use in radiation dosimetry. The optimal condition for OSL readout with blue light stimulation were designated using a commercially available Risø TL/OSL reader. KCl was studied in three sample forms: crystals, powder and pellets. The following OSL characteristics were determined: signal reproducibility, OSL measurement-induced sensitivity changes, temperature dependence of OSL and signal stability over time. The results show a high reproducibility of KCl samples and strong sensitivity changes, which can be corrected for by using a test-dose. The long-term OSL studies confirmed the occurrence of both inverse fading and fading phenomena in KCl. In addition, a comparison with corresponding measurements using sodium chloride (NaCl) were carried out. Although it was confirmed that NaCl is more suitable for dosimetry, there might be benefits of combining NaCl with KCl for more accurate absorbed dose determinations.
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| 6. |
- Nilsson, Jonas M.C., et al.
(författare)
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A rotating-slit-collimator-based gamma radiation mapper
- 2017
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Ingår i: Journal of Environmental Radioactivity. - : Elsevier BV. - 0265-931X. ; 177, s. 225-232
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Tidskriftsartikel (refereegranskat)abstract
- For situations with radioactive material out of control where it may be physically difficult or prohibited to access areas close to the source, measurements from distance may be the only way to assess the radiation environment. Using collimated detectors will provide means to locate the direction of the radiation from the source. To investigate the possibilities of mapping gamma emitting radioactive material in a closed non-enterable area, a tentative system for mapping radioactive materials from a distance was built. The system used a computer controlled cylindrical rotating slit collimator with a high purity germanium detector placed in the cylinder. The system could be placed on a car-towed trailer, with the centre of the detector about 1.4 m above ground. Mapping was accomplished by the use of a specially developed image reconstruction algorithm that requires measurements from two or more locations around the area to be investigated. The imaging capability of the system was tested by mapping an area, 25 by 25 m2, containing three 330 MBq 137Cs point sources. Using four locations outside the area with about 20 min measuring time in each location and applying the image reconstruction algorithm on the deconvoluted data, the system indicated the three source locations with an uncertainty of 1–3 m. The results demonstrated the potential of using collimated mobile gamma radiometry combined with image reconstruction to localize gamma sources inside non-accessible areas.
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| 7. |
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| 8. |
- Rääf, Christopher L, et al.
(författare)
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A Novel Swedish Master’s Degree Programme for Applied Radiation Protection.
- 2012
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Ingår i: 13th International Congress of the International Radiation Protection Association (IRPA) in Glasgow, 13-18 May 2012.
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Konferensbidrag (refereegranskat)abstract
- Since the beginning of the 1960s Sweden has had a university programme for Medical Radiation Physics. This programme was expanded to a MSc level, when it was redesigned (mid-2000s) to generate a professional license as a clinical medical physicist, warranted by the Swedish National Board of Health and Welfare. The main end-users for this programme have been i.) hospitals and clinics, and ii.) research departments. Nuclear industries and authorities associated with radiation protection and emergency preparedness did not always recruit students from this particular programme as it was focused on topics related to the hospital environment. In the beginning of the 2000s it was identified that Sweden, as many other countries, needed an additional and supplementary skill in radiation protection, to meet a new threat from nuclear and radiological events, also including malovent use of radioactvity. A new cadre of experts had to be formed with competence within radiation protection for non-hospital issues in the next generation. In accordance with this need for a new profession, here referred to as applied radiation protection, the Medical Physics departments at Lund University (ass. prof. C. L. Rääf) and Göteborg University (prof. M. Isaksson) were commissioned by the Swedish Radiation Protection Authority in 2008 to elaborate an educational programme on a Master’s level. This programme, Applied radition protection, has recently been accepted by the Sahlgrenska Academy board of basic education at Göteborg University and is presented here. The programme is 2 years, ending with a Master thesis (30 ECTS), containing six principal courses; i.) Basic radiation protection – an introductory course to fundamental radiation protection. ii.) Emergency preparedness and management in radiological or nuclear emergencies – focusing on the role of various authorities and stakeholders in the society. iii.) Detectors and measurement methods in applied radiation protection – introducing the most common types of detectors used in stationary and mobile radiometry systems, including also search strategies for localising lost radiation sources. iv.) On-site management of radiological and nuclerar events – consisting of practical field exercises performed together with rescue workers and first responders. v.) Management of patients subjected to radiation exposure in emergency situations – focusing on the medical treatment of patients, from damage site to special medicine, including practical exercises. vi.) Nuclear energy fuel cycle – an overview of the topic with special attention to radiation protection issues, including also nuclear weapons. This Master programme is planned to be launched in autumn 2012 and is open also for applications from foreign students. For those students that graduate and wish to deepen their skills and expertise in this field, several PhD projects will be offered.
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| 9. |
- Rääf, Christopher L., et al.
(författare)
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Average uranium bedrock concentration in Swedish municipalities predicts male lung cancer incidence rate when adjusted for smoking prevalence: Indication of a cumulative radon induced detriment?
- 2023
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Ingår i: Science of the Total Environment. - : Elsevier BV. - 0048-9697 .- 1879-1026. ; 855
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Tidskriftsartikel (refereegranskat)abstract
- Bedrock U has been used as a proxy for local indoor radon exposure. A preliminary assessment of cancer incidence rate in a cohort of 809,939 adult males living in 9 different Swedish counties in 1986 has been used to correlate the cumulative lung cancer and total cancer (excluding lung) incidence rates between 1986 and 2020, respectively with the municipality average value of bedrock U concentration obtained from Swedish geological Survey (SGU). To control for regional difference in tobacco smoking, data on county average smoking prevalence, obtained from a survey conducted by the Public Health Agency of Sweden from 2001 to 2004, was used. Regression analysis shows that there is a significant positive correlation between smoking prevalence adjusted lung cancer incidence rate in males and the municipality bedrock U concentration (R2 = 0.273 with a slope 5.0 ± 0.87·10−3 ppm−1). The correlation is even more significant (R2 = 0.759 with a slope = 4.8 ± 0.25·10−3 ppm−1) when assessed on population weighted cancer incidence data binned in nine intervals of municipality average bedrock U concentration (ranging from 0.97 to 4.9 ppm). When assessing the corresponding correlations for total cancer incidence rate (excluding cancer of the lung) with adjustment for smoking prevalence, there appears to be no or little correlation with bedrock U concentration (R2 = 0.031). We conclude that an expanded future study needs age-standardized cancer incidence data to obtain a more consistent exposure-response model. Such model could be used to predict future lung cancer cases based on geological survey maps of bedrock U as an alternative to laborious indoor radon measurements, and to discern what future lung cancer rates can be expected for a population nearing zero smoking prevalence, with and without radon prevention. © 2022 The Authors
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| 10. |
- Rääf, Christopher L., et al.
(författare)
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Time‑dependence of decontamination efficiency after a fallout of gamma‑emitting radionuclides in suburban areas: a theoretical outlook on topsoil removal
- 2022
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 12:1
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Tidskriftsartikel (refereegranskat)abstract
- Decontamination of urban areas may be necessary in the case of extensive fallout of radioactive material after a nuclear accident, as removal of contaminated soil and vegetation will significantly reduce doses for the residents in an area affected by fallout. Experience from Japan shows that cleanup operations of urban areas may take years despite investment in ample resources. The time delay between the initial fallout and completion of the decontamination measures allows natural and physical processes to affect the results. The efficiency of the decontamination will therefore depend significantly on time. Radioecological modeling and computer simulation of urban topography with one-story houses were applied in this study to estimate action-influenced time-integrated dose reductions (TDR) of contaminated topsoil removal as a function of time after the fallout. Results indicate that the TDR decreases gradually after the fallout depending on the vertical migration rate of radiocesium and, to some extent, the initial 134Cs/137Cs ratio. Delaying the topsoil removal from 1 to 10 years will result in a TDR decrease by more than a factor of two. Removing the topsoil within one year after fallout results typically in an averted effective dose between 34 and 80 mSv per MBq m− 2 deposition of 137Cs for residents in wooden houses. The corresponding values for residents in brick houses are about 50% lower due to higher shielding. Additional modeling is needed to estimate how age and sex influence the averted detriment to affected cohorts. In addition, more in-depth knowledge of how the efficiency of topsoil removal in practice compares with hypothetical models and the effect of incomplete removal of radiocesium is needed to improve calculations of TDR values.
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| 11. |
- Rääf, Christopher, et al.
(författare)
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Transfer of (137)Cs from Chernobyl debris and nuclear weapons fallout to different Swedish population groups.
- 2006
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Ingår i: Science of the Total Environment. - : Elsevier BV. - 1879-1026 .- 0048-9697. ; 367:Feb 24, s. 324-340
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Tidskriftsartikel (refereegranskat)abstract
- Data from measurements on the body burden Of (CS)-C-134, Cs-137 and K-40 in various Swedish populations between 1959 and 2001 has been compiled into a national database. The compilation is a co-operation between the Departments of Radiation Physics in Malmo and Goteborg, the National Radiation Protection Authority (SSI) and the Swedish Defense Research Agency (FOI). In a previous study the effective ecological half time and the associated effective dose to various Swedish populations due to internal contamination of Cs-134 and Cs-137 have been assessed using the database. In this study values of human body burden have been combined with data on the local and regional ground deposition of fallout from nuclear weapons tests (only Cs-137) and Chernobyl debris (both Cs-134 and (CS)-C-137), which have enabled estimates of the radioecological transfer in the studied populations. The assessment of the database shows that the transfer of radiocesium from Chernobyl fallout to humans varies considerably between various populations in Sweden. In terms of committed effective dose over a 70 y period from internal contamination per unit activity deposition, the general (predominantly urban) Swedish population obtains 20-30 mu Sv/kBq m(-2). Four categories of populations exhibit higher radioecological transfer than the general population; i.) reindeer herders (similar to 700 mu Sv/kBq m(-2)), ii.) hunters in the counties dominated by forest vegetation (similar to 100 mu Sv/kBq m(-2)), iii.) rural non-farming populations living in sub-arctic areas (40-150 mu Sv/kBq m(-2)), and iv.) farmers (similar to 50 mu Sv/kBq m(-2)). Two important factors determine the aggregate transfer from ground deposition to man; i.) dietary habits (intakes of foodstuff originating from natural and semi-natural ecosystems), and ii.) inclination to follow the recommended food restriction by the authorities. The transfer to the general population is considerably lower (similar to a factor of 3) for the Chernobyl fallout than during the 1960s and 70s, which is partly explained by a higher awareness of the pathways of radiocaesium to man both by the public and by the regulating authorities, and by the time-pattern of the nuclear weapons fallout during the growth season in Sweden. (c) 2005 Elsevier B.V. All rights reserved.
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| 12. |
- Sundström, Jonathan, 1993, et al.
(författare)
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LARCalc, a tool to estimate sex‑ and age‑specific lifetime attributable risk in populations after nuclear power plant fallout
- 2023
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Ingår i: Scientific Reports. - 2045-2322. ; 13
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Tidskriftsartikel (refereegranskat)abstract
- A tool called LARCalc, for calculating the radiological consequences of accidental large scale nuclear power plant releases based on estimates of 137Cs ground deposition, is presented. LARCalc is based on a previously developed models that has been further developed and packaged into an easy-touse decision support tool for training of decision makers. The software visualises the radiological impact of accidental nuclear power plant releases and the effects of various protective measures. It is thus intended as a rapid alternative for planning protective measures in emergency preparedness management. The tool predicts projected cumulative effective dose, projected lifetime attributable cancer risk, and residual dose for some default accidental release scenarios. Furthermore, it can predict the residual dose and avertable cumulative lifetime attributable risk (LAR) resulting from various protective measures such as evacuation and decontamination. It can also be used to predict the avertable collective dose and the increase in cancer incidence within the specified population. This study presents the theoretical models and updates to the previous models, and examples of different nuclear fallout scenarios and subsequent protective actions to illustrate the potential use of LARCalc.
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| 13. |
- Ören, Ünal, et al.
(författare)
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Silicon diode as an alpha particle detector and spectrometer for direct field measurements
- 2016
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Ingår i: Radiation Protection Dosimetry. - : Oxford University Press (OUP). - 0144-8420 .- 1742-3406. ; 170:1-4, s. 247-251
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Tidskriftsartikel (refereegranskat)abstract
- A windowless silicon (Si) diode (4 mm2) was evaluated as alpha particle detector and spectrometer for field measurements. It was irradiated with alpha particles from a 241Am (2.3 kBq) and a 210Po (9 kBq) source at source-detector distances (SDD) of 0.5, 1.0 and 1.8 cm. The energy resolution in terms of full width at half maximum was 281, 148 and 113 keV for SDD of 0.5, 1.0 and 1.8 cm, respectively. The minimum detectable activity increased from 0.08 to 0.83 Bq when the SDD increased from 0.5 to 1.8 cm. The detector has the potential for several alpha spectrometric applications, such as monitoring for wound, skin and surface contamination at nuclear fuel facilities, nuclear power plants and facilities handling radioactive waste. Other areas are environmental surveys following releases of actinides at accidents in nuclear power plants and in connection with other radiological or nuclear scenarios.
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| 14. |
- Östlund, Karl, et al.
(författare)
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Peak-to-valley ratios for three different HPGe detectors for the assessment of 137Cs deposition on the ground and the impact of the detector field-of-view
- 2017
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Ingår i: Applied Radiation and Isotopes. - : Elsevier BV. - 0969-8043. ; 120, s. 89-94
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Tidskriftsartikel (refereegranskat)abstract
- The peak-to-valley (PTV) method was investigated experimentally comparing PTV ratios for three HPGe detectors, with complementary Monte Carlo simulations of scatter in air for larger source-detector distances. The measured PTV ratios for 137Cs in air were similar for three different detectors for incident angles between 0 and 90°. The study indicated that the PTV method can differentiate between surface and shallow depth sources if the detector field of view is limited to a radius of less than 3.5 m.
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| 15. |
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