| 1. |
- Almén, Anja, et al.
(författare)
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Challenges assessing radiation risk in image-guided treatments-implications on optimisation of radiological protection
- 2018
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Ingår i: Journal of Radiological Protection. - : IOP Publishing. - 0952-4746 .- 1361-6498. ; 38:3, s. 1064-1076
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Tidskriftsartikel (refereegranskat)abstract
- The present work explores challenges when assessing organ dose and effective dose concerning image-guided treatments. During these treatments considerable x-ray imaging is employed using technically advanced angiographic x-ray equipment. Thus, the radiation dose to organs and the related radiation risk are relatively difficult to assess. This has implications on the optimisation process, in which assessing radiation dose is one important part. In this study, endovascular aortic repair treatments were investigated. Organ dose and effective dose were assessed using Monte Carlo calculations together with a detailed specification of the exposure situation and patient size. The resulting normalised organ dose and effective dose with respect to kerma-area product for patient sizes and radiation qualities representative for the patient group were evaluated. The variability and uncertainty were investigated and their possible impact on optimisation of radiation protection was discussed. Exposure parameters, source to detector distances etc varied between treatments and also varied between image acquisitions during one treatment. Thus the derived normalised organ dose and effective dose exhibited a large range of values depending greatly on used exposure parameters and patient configuration. The derived normalised values for effective dose varied approximately between 0.05 and 0.30 mSv per Gy.cm(2) when taking patient sizes and exposure parameters into consideration, the values for organ doses exhibited even larger variation. The study shows a possible systematic error for derived organ doses and effective dose up to a factor of 7 if detailed exposure or patient characteristics are not known and/or not taken into consideration. The intra-treatment variability was also substantial and the normalised dose values varied up to a factor of 2 between image acquisitions during one treatment. The study shows that the use of conversion factors that are not adapted to the clinic can cause the radiation dose to be exaggerated or underestimated considerably. A conclusion from the present study is that the systematic error could be large and should be estimated together with random errors. A large uncertainty makes it difficult to detect true differences in radiation dose between methods and technology-a prerequisite for optimising radiation protection for image-guided treatments.
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| 2. |
- Hinrichsen, Y, et al.
(författare)
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Introducing the concept of the isodose for optimisation of decontamination activities in a radioactive fallout scenario
- 2018
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Ingår i: Journal of Radiological Protection. - : IOP Publishing. - 1361-6498 .- 0952-4746. ; 38:4, s. 1293-1310
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Tidskriftsartikel (refereegranskat)abstract
- In the recovery phase after a radioactive release incident, it is important to be able to focus decontamination operations on the areas that contribute most to the radiation dose. Monte Carlo simulations were applied to determine the shielding effect of a building against radiation from various directions, also giving information on the dose contributions at various locations inside the building from specific areas outside. The concept of the isodose was developed to optimise decontamination activities, and was applied as isodose lines to define the smallest areas that lead to a certain dose reduction through decontamination of areas surrounding the building. The shape and position of the isodose lines depend on the building's geometry, wall thickness, and material, and on the observation point inside the building. Calculations have been made with a surface resolution of 1 m2 for four observation points in a modular building, assuming depositions of 137Cs and 60Co on the ground surface and on the roof, as well as 1 cm below the ground surface to represent ground penetration. For example, a ten times as large area would have to be decontaminated to increase the dose reduction from 10% to 30%, if it is assumed that all the contamination is located at a depth of 1 cm.
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| 3. |
- Isaksson, Mats, 1961, et al.
(författare)
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Absorbed dose rate coefficients for 134Cs and 137Cs with steady-state distribution in the human body : S-coefficients revisited
- 2021
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Ingår i: Journal of Radiological Protection. - : Institute of Physics Publishing (IOPP). - 0952-4746 .- 1361-6498. ; 41:4, s. 1213-1227
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Tidskriftsartikel (refereegranskat)abstract
- In the event of an accidental release of radioactive elements from a nuclear power plant, it has been shown that the radionuclides contributing the most to long-term exposure are Cs-134 and Cs-137. In the case of nuclear power plant fallout, with subsequent intake of radionuclides through the food chain, the internal absorbed dose to target tissues from protracted intake of radionuclides needs to be estimated. Internal contamination from food consumption is not caused by a single intake event; hence, the committed equivalent dose, calculated by a dose coefficient or dose per content function, cannot be easily used to calculate the cumulative absorbed dose to relevant target tissues in the body. In this study, we calculated updated absorbed dose rate coefficients for Cs-134 and Cs-137 based on data from the International Commission on Radiological Protection (ICRP) on specific absorbed fractions. The absorbed dose rate coefficients are provided for male and female adult reference phantoms, respectively, assuming a steady-state distribution of Cs that we calculated from the ICRP biokinetic model for Cs. With these coefficients, the absorbed dose to the listed target tissues, separately and to the total body, are related to the number of nuclear transitions (time-integrated activity) in each listed source region. Our new absorbed dose rate coefficients are given for the complete set of target tissues and have not been presented before. They are also provided for aggregated categories of organs to facilitate epidemiological studies.
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| 4. |
- Lagergren Lindberg, Marita, et al.
(författare)
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Mental health and psychosocial consequences linked to radiation emergencies - Increasingly recognised concerns
- 2022
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Ingår i: Journal of Radiological Protection. - : IOP Publishing. - 0952-4746 .- 1361-6498. ; 42:3
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Forskningsöversikt (refereegranskat)abstract
- A major radiological or nuclear emergency may, apart from causing a substantial loss of life and physical damage, also put a substantial strain on affected societies with social, economic and political consequences. Although such emergencies are relatively uncommon, it is now being increasingly recognised that their subsequent psychosocial impact can be widespread and long lasting. Mental health effects, such as depression, anxiety and post-traumatic stress disorder, are highly represented in a population affected by a radiation disaster. In order to reach the majority of the people affected by radiation accidents, we need to be aware of how to distribute relevant and accurate information related to both short- and long-term medical effects. Effective risk communication is associated with improved compliance with any given recommendations. It is important to protect the public from physical radiation damage, but it is also essential to take into account the social and mental health effects that radiation disasters may induce. This article provides a brief review of recent reporting on the psychological consequences after a major radiation emergency.
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| 5. |
- O'Connor, U, et al.
(författare)
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Feasibility study of computational occupational dosimetry : evaluating a proof-of-concept in an endovascular and interventional cardiology setting
- 2022
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Ingår i: Journal of Radiological Protection. - : IOP Publishing. - 1361-6498 .- 0952-4746. ; 42:4
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Tidskriftsartikel (refereegranskat)abstract
- Individual monitoring of radiation workers is essential to ensure compliance with legal dose limits and to ensure that doses are As Low As Reasonably Achievable. However, large uncertainties still exist in personal dosimetry and there are issues with compliance and incorrect wearing of dosimeters. The objective of the PODIUM (Personal Online Dosimetry Using Computational Methods) project was to improve personal dosimetry by an innovative approach: the development of an online dosimetry application based on computer simulations without the use of physical dosimeters. Occupational doses were calculated based on the use of camera tracking devices, flexible individualised phantoms and data from the radiation source. When combined with fast Monte Carlo simulation codes, the aim was to perform personal dosimetry in real-time. A key component of the PODIUM project was to assess and validate the methodology in interventional radiology workplaces where improvements in dosimetry are needed. This paper describes the feasibility of implementing the PODIUM approach in a clinical setting. Validation was carried out using dosimeters worn by Vascular Surgeons and Interventional Cardiologists during patient procedures at a hospital in Ireland. Our preliminary results from this feasibility study show acceptable differences of the order of 40% between calculated and measured staff doses, in terms of the personal dose equivalent quantity Hp(10), however there is a greater deviation for more complex cases and improvements are needed. The challenges of using the system in busy interventional rooms have informed the future needs and applicability of PODIUM. The availability of an online personal dosimetry application has the potential to overcome problems that arise from the use of current dosimeters. In addition, it should increase awareness of radiation protection among staff. Some limitations remain and a second phase of development would be required to bring the PODIUM method into operation in a hospital setting. However, an early prototype system has been tested in a clinical setting and the results from this two-year proof-of-concept PODIUM project are very promising for future development.
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| 6. |
- Raaf, Christopher L., et al.
(författare)
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In vivo measurement of pre-operational spallation source workers : Baseline body burden levels and detection limits of relevant gamma emitters using high-resolution gamma spectrometry
- 2019
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Ingår i: Journal of Radiological Protection. - : IOP Publishing. - 0952-4746 .- 1361-6498. ; 40:1, s. 119-133
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Tidskriftsartikel (refereegranskat)abstract
- As a measure to prepare for long-term internal dose monitoring of workers at the European Spallation Source (ESS) in Lund, Sweden, operated by the European Research Infrastructure Consortium (ERIC), as well as to enhance emergency preparedness against accidental releases, a series of in vivo measurements were conducted using a high-resolution HPGe detector with a 123% relative efficiency (1.332 MeV). This study describes the whole-body counting set-up, calibration procedure, and subsequent validation measurements using conventional NaI(Tl)-scanning-bed geometry on a selection of workers from the ESS. Detection limits for the relevant gamma emitters 7Be, 172Hf, and 182Ta were determined to be 65 Bq, 130 Bq, and 22 Bq, respectively, using a 2400 s acquisition time. The baseline measurements suggest that care must be taken to ensure that the fluctuations in the presence of radon daughters 214Bi and 214Pb are minimised by, for example, ensuring a minimum air exchange between the measuring room and the ambient air, and by demanding that the measured subjects change clothes and shower before measurement. Furthermore, in a monitoring program for internal doses to spallation source workers, the presence of radionuclides originating from non-work-related sources (such as 226Ra from private water wells or 137Cs from intakes of Chernobyl contaminated foodstuffs), or radionuclides from previous work history (such as 60Co within the nuclear power industry), must be considered.
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| 7. |
- Rääf, C., et al.
(författare)
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Averting cumulative lifetime attributable risk (LAR) of cancer by decontamination of residential areas affected by a large-scale nuclear power plant fallout: Time aspects of radiological benefits for newborns and adults
- 2020
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Ingår i: Journal of Radiological Protection. - : IOP Publishing. - 0952-4746 .- 1361-6498. ; 40:3, s. 790-814
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Tidskriftsartikel (refereegranskat)abstract
- The averted cumulative lifetime attributable risk (LAR), the residual dose and highest ground deposition of 137Cs complying with a reference dose level of 20 mSv y-1 to an individual returning after one year to an area contaminated by nuclear power plant (NPP) fallout were evaluated by applying an existing exposure model designed to compute age- and gender-dependent time integrated LAR. The model was applied to four types of nuclear fallout scenarios, partly based on data from the Chernobyl and Fukushima releases and from theoretical source terms from Swedish NPPs. For rapid decontamination measures that achieve a 50% relative reduction in external dose rate within 1 y, compliance with the reference level 20 mSv y-1 can be attained for an initial 137Cs ground deposition of up to 2 MBq m-2 with relaxed food restrictions. This compliance can be attained at even higher ground deposition (up to 3.5 MBq m-2) if using the strict food restrictions employed in Japan after 2011. Considering longer than 1 year return times it was also found that the benefit of implementing decontamination decreases rapidly with time (2-3 y half-time), especially if the fallout has a high initial 134Cs to 137Cs activity ratio and if the ecological half-time of the external dose rate is short (<5 y). Depending on fallout scenario the averted cumulative LAR for newborn girls by decontamination that is achieved after 5 y is only between 6% and 11% of that obtained by evacuation alone during the same time, indicating a rather limited radiological benefit of decontamination if delayed more than a few years. We conclude that decision makers and emergency response planners need to consider that protracted decontamination measures may have limited radiological benefit compared with evacuation in terms of averted future cancer cases, albeit it may have other societal benefits.
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| 8. |
- Waldner, Lovisa, et al.
(författare)
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Experimentally determined and Monte Carlo-calculated energy dependence of NaCl pellets read by optically stimulated luminescence for photon beams in the energy range 30 keV to 1.25 MeV
- 2020
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Ingår i: Journal of Radiological Protection. - : IOP Publishing. - 0952-4746 .- 1361-6498. ; 40:4, s. 1321-1335
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Tidskriftsartikel (refereegranskat)abstract
- Ordinary salt, NaCl, has many properties suitable for dosimetry and has been suggested for both retrospective and prospective optically stimulated luminescence (OSL) dosimetry. Lately, the focus has been on NaCl that is compressed into solid pellets, as this improves both its handling and dosimetric properties. In this project, the energy dependence of NaCl pellets produced in-house was investigated for photon energies between 30 and 1.25 MeV. The NaCl pellets were first exposed to free-in-air conditions, and the estimated absorbed dose to the NaCl pellets was compared to the air kerma, K air, at the point of exposure. Second, a backscatter medium of polymethyl methacrylate (PMMA) was added, and NaCl pellets were exposed when positioned on a ISO slab phantom to relate the response in the NaCl to the personal dose equivalent, H p(10). The results show a significant energy dependence for exposure to low-energy photons with a peak over-response compared to K air and H p(10) of up to 18. Comparisons with Monte Carlo simulations show good agreement, even though the simulations cannot account for properties related to the intrinsic luminescence effects of the NaCl pellets or the readout and calibration process. The finite thickness of the NaCl pellet makes it an imperfect Bragg-Grey cavity, which complicates the behaviour of the energy dependence. The results presented here may serve as an important basis for further experimental and theoretical modelling of a build-up layer and filters in efforts to develop a passive personal dosemeter based on NaCl.
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| 9. |
- Raaf, C. L., et al.
(författare)
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A model for estimating the total absorbed dose to the thyroid in Swedish inhabitants following the Chernobyl Nuclear Power Plant accident : implications for existing international estimates and future model applications
- 2019
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Ingår i: Journal of Radiological Protection. - : IOP Publishing. - 0952-4746 .- 1361-6498. ; 39:2, s. 522-547
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Tidskriftsartikel (refereegranskat)abstract
- The time-integrated absorbed dose to the thyroid gland in the years after a fallout event can indicate the potential excess number of thyroid cancers among young individuals after a radionuclide release. Typical mean values of the absorbed dose to the thyroid have been calculated previously using reported data on radioiodine obtained from air sampling and dairy milk surveys in Sweden after the Chernobyl fallout, not including the contribution from Cs-134 and Cs-137. We have developed a model for Swedish conditions taking these additional dose contributions into account. Our estimate of the average time-integrated absorbed dose to the thyroid, D-th,D-tot, during the first 5 years after fallout ranged from 0.5-4.1 mGy for infants and from 0.3-3.3 mGy for adults. The contribution to D-th,D-tot, from I-131 through inhalation and milk consumption varied considerably among different regions of Sweden, ranging from 9%-79% in infants, and from 4%-58% in adults. The external irradiation and exposure from the ingestion of (CS)-C-134,137 in foodstuffs accounted for the remaining contributions to D-th,D-tot, (i.e. up to 96% for adults). These large variations can be explained by the highly diverse conditions in the regions studied, such as different degrees of fractionation between wet and dry deposition, different grazing restrictions on dairy cattle, and differences in (CS)-C-134,137 transfers through food resulting from differences in the local fallout. It is our conclusion that the main contribution to D-th,D-tot, from nuclear power plant fallout in areas subjected to predominantly wet deposition will be from external exposure from ground deposition, followed by internal exposure from contaminated food containing the long-lived fission product Cs-137 and the neutron-activated fission product (CS)-C-134. The contribution from (CS)-C-134,137 to the thyroid absorbed dose should thus be taken into account in future epidemiological studies.
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| 10. |
- Ören, Ünal, et al.
(författare)
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Detection of radioactive fragments in patients after radiological or nuclear emergencies using computed tomography and digital radiography.
- 2014
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Ingår i: Journal of Radiological Protection. - : IOP Publishing. - 1361-6498 .- 0952-4746. ; 34:1, s. 231-247
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Tidskriftsartikel (refereegranskat)abstract
- A comparison has been carried out between standard-dose computed tomography, non-diagnostic computed tomography and digital radiography with respect to their suitability for detecting radioactive fragments associated with nuclear or radiological events such as debris from radiological dispersal devices. The purpose was to investigate if radiographic imaging is justified for the detection and localisation of radioactive fragments in affected patients.Fragments of uranium (U), copper (Cu), iron (Fe) and volcanic ash with effective diameters ranging from (approximately) 100 to 700 μm were selected. The fragments were positioned at two different locations on an anatomical torso phantom and images were produced with standard-dose CT, non-diagnostic CT and digital radiography. Capsules with radionuclides of (137)Cs, (60)Co and (99m)Tc were also positioned in the phantom and the effective doses were estimated for radionuclide exposures as well as for standard-dose CT, non-diagnostic CT and digital radiography. For standard-dose CT and digital radiography, U, Cu and Fe fragments were detected in sizes down to 100-180, 250-300 and 300-400 μm respectively. For the non-diagnostic CT the results were 180-250 μm (for U), 300-400 μm (for Cu) and 400-500 μm (for Fe). The effective dose from the standard-dose CT, non-diagnostic CT and digital radiography was 5.6, 1.9 and 0.76 mSv. Corresponding doses from (137)Co, (60)Co and (99m)Tc positioned at the site of fragments were in the range of 0.07-0.1, 0.32-0.45 and 0.08-0.09 mSv per MBq during 24 h. We conclude that, for a number of gamma emitters with activity levels on the order of magnitude of megabecquerel, imaging using ionising radiation can be justified since the effective dose from the radionuclides will exceed the dose from the radiological examination.
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