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Andrew S. Murray - One of the best experts on this subject based on the ideXlab platform.
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Utilisation of OSL from Table Salt in Retrospective Dosimetry
Japanese Journal of Health Physics, 2011Co-Authors: Hiroki Fujita, Mayank Jain, Andrew S. MurrayAbstract:Common salt (NaCl) has previously been suggested for use in dose estimation in accident Dosimetry. In this study, we investigated the optically stimulated luminescence (OSL) and violet thermoluminescence (VTL) characteristics of “Aji-Shio” (Ajinomoto), a Japanese commercial salt. A comparison of OSL and TL signals allowed identification of common source traps. The initial OSL signal contained a dominant thermally unstable component, which necessitated prior heat treatment. Based on these luminescence characteristics, a single-aliquot regenerative-dose (SAR) OSL protocol was modified and tested. The protocol worked very well for six types of salt, but not for four other types of salt. A minimum detection limit of -15 mGy was estimated using the OSL protocol; this is lower than the value obtained from other forms of OSL Retrospective Dosimetry and lower than that obtained using electron spin resonance (ESR) Dosimetry. It was concluded that the OSL from Japanese commercial salt could be used successfully to derive precise estimates of accident dose.
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Optically Stimulated Luminescence in Retrospective Dosimetry
Radiation Protection Dosimetry, 2002Co-Authors: L. Bøtter-jensen, Andrew S. MurrayAbstract:Since the beginning of the 1990s the exploration of optically stimulated luminescence (OSL) in Retrospective accident Dosimetry has driven an intensive investigation and development programme at Rise into measurement facilities and techniques. This paper reviews some of the outcomes of this programme, including the evaluation of the single-aliquot regenerative-dose (SAR) measurement protocol with brick quartz and the determination of dose-depth profiles in building materials as a guide to determining the mean energy of the incident radiation. Investigations into heated materials are most advanced, and a lower detection limit for quartz extracted from Chernobyl bricks was determined to be
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Retrospective Dosimetry: Dose Evaluation using Unheated and Heated Quartz from a Radioactive Waste Storage Building
Radiation Protection Dosimetry, 2002Co-Authors: Mayank Jain, L. Bøtter-jensen, Andrew S. Murray, Högne JungnerAbstract:In the assessment of dose received from a nuclear accident, considerable attention has been paid to Retrospective Dosimetry using heated materials such as household ceramics and bricks. However, unheated materials such as mortar and concrete are more commonly found in industrial sites and particularly in nuclear installations. These materials contain natural dosemeters such as quartz, which usually is less sensitive than its heated counterpart. The potential of quartz extracted from mortar in a wall of a low-level radioactive-waste storage facility containing distributed sources of 60 Co and 137 Cs has been investigated. Dose-depth profiles based on small aliquots and single grains from the quartz extracted from the mortar samples are reported here. These are compared with results from heated quartz and polymineral fine grains extracted from an adjacent brick, and the integrated dose recorded by environmental TLDs.
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Optically stimulated luminescence in Retrospective Dosimetry.
Radiation protection dosimetry, 2002Co-Authors: L. Bøtter-jensen, Andrew S. MurrayAbstract:Since the beginning of the 1990s the exploration of optically stimulated luminescence (OSL) in Retrospective accident Dosimetry has driven an intensive investigation and development programme at Risø into measurement facilities and techniques. This paper reviews some of the outcomes of this programme, including the evaluation of the single-aliquot regenerative-dose (SAR) measurement protocol with brick quartz and the determination of dose-depth profiles in building materials as a guide to determining the mean energy of the incident radiation. Investigations into heated materials are most advanced, and a lower detection limit for quartz extracted from Chernobyl bricks was determined to be
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Using the OSL single-aliquot regenerative-dose protocol with quartz extracted from building materials in Retrospective Dosimetry
Radiation Measurements, 2000Co-Authors: L. Bøtter-jensen, Andrew S. Murray, Saran Solongo, Debabrata Banerjee, Högne JungnerAbstract:We report on the application of the single-aliquot regenerative-dose (SAR) protocol to the optically stimulated luminescence signal from quartz extracted from fired bricks and unfired mortar in Retrospective Dosimetry. The samples came from a radioactive materials storage facility, with ambient dose rates of about 0.1 mGy/h. A detailed dose-depth profile was analysed from one brick, and compared with dose records from area TL dosemeters. Small-aliquot dose-distributions were analysed from the mortar samples; one associated with the exposed brick, and one from a remote site exposed only to background radiation. We conclude that unfired materials have considerable potential in Retrospective Dosimetry.
Hiroki Fujita - One of the best experts on this subject based on the ideXlab platform.
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Retrospective Dosimetry using japanese brick quartz a way forward despite an unstable fast decaying osl signal
Radiation Measurements, 2011Co-Authors: Hiroki Fujita, Mayank Jain, A S MurrayAbstract:Abstract Quartz extracted from heated bricks has been previously suggested for use in dose estimation in accident Dosimetry, but this technique has never been applied before to Japanese quartz which often has unusual OSL characteristics. In this study the optically stimulated luminescence (OSL) characteristics of quartz extracted from a Japanese commercial red brick produced by Mishima – Renga – Seizoujyo Co. are studied. These companies are based in the Aichi Prefecture (capital Nagoya), which accounts for about half of the red brick production in Japan. A comparison of TL (thermoluminescence) and OSL signals has been carried out towards identification of common source traps. It is observed that OSL from Japanese brick quartz shows unusual luminescence characteristics; in particular, the initial fast decaying OSL signal contains a dominant (>90%) thermally unstable component related to the 85 °C TL peak, which necessitates a prior heat treatment. A single-aliquot regenerative-dose (SAR) protocol is developed and tested using thermal treatments intended to isolate a stable dosimetric signal. A minimum detection limit of ∼65 mGy is then estimated using this protocol. Following irradiation using 60 Co and 137 Cs, dose–depth profiles were measured on two different commercial brick types (Mishima – Renga – Seizoujyo Co. and Hase – Renga Co.) with 5 Gy and 10 Gy surface doses. The profiles derived from the two sources were readily distinguishable. It is concluded that the OSL signals from the two types of Japanese brick quartz examined here can be used to derive precise estimates of accident dose, and, possibly to distinguish between sources of gamma radiation in a nuclear accident. To our knowledge, this is the first report on the existence of an unstable fast decaying OSL signal in quartz derived from bricks, and demonstrates a way forward with such samples in Retrospective Dosimetry.
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Utilisation of OSL from Table Salt in Retrospective Dosimetry
Japanese Journal of Health Physics, 2011Co-Authors: Hiroki Fujita, Mayank Jain, Andrew S. MurrayAbstract:Common salt (NaCl) has previously been suggested for use in dose estimation in accident Dosimetry. In this study, we investigated the optically stimulated luminescence (OSL) and violet thermoluminescence (VTL) characteristics of “Aji-Shio” (Ajinomoto), a Japanese commercial salt. A comparison of OSL and TL signals allowed identification of common source traps. The initial OSL signal contained a dominant thermally unstable component, which necessitated prior heat treatment. Based on these luminescence characteristics, a single-aliquot regenerative-dose (SAR) OSL protocol was modified and tested. The protocol worked very well for six types of salt, but not for four other types of salt. A minimum detection limit of -15 mGy was estimated using the OSL protocol; this is lower than the value obtained from other forms of OSL Retrospective Dosimetry and lower than that obtained using electron spin resonance (ESR) Dosimetry. It was concluded that the OSL from Japanese commercial salt could be used successfully to derive precise estimates of accident dose.
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Retrospective Dosimetry Using Violet Thermoluminescence from Natural Quartz in Soil
Journal of Nuclear Science and Technology, 2008Co-Authors: Hiroki FujitaAbstract:The violet thermoluminescence (VTL)-Retrospective Dosimetry was developed and was then confirmed to be effectual method in emergency situation using quartz extracts from surface soil collected around tokai, Ibaraki, Japan. All of the measurements were undertaken by VTL measurement condition using modified single aliquot regenerative-dose protocol.An on-line automatic spectrometric system installed with a small spectrometer and a CCD camera unit was developed for weak and changeable TL-spectrum measurement with rising temperature for application to natural quartz. From spectrometry of the TL, two emission peaks, consisting of 400 nm and 620 nm, were revealed. In this paper, 400 nm were only investigated.The accumulated γ-doses of quartz extracts from surface soils which were 10 m from radiation source at gamma field at the Institution of Radiation Breeding (IRB), National Institute of Agrobiological Sciences (NIAS), were evaluated to be 0.8~0.9 Gy using VTL measurement, concordant with the value measured b...
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Usability of VTL from natural quartz grains for Retrospective Dosimetry
Radiation protection dosimetry, 2006Co-Authors: Hiroki Fujita, Tetsuo HashimotoAbstract:To develop Retrospective Dosimetry of unexpected radiation accident, basic studies on violet thermoluminescence (VTL) phenomena were conducted using natural quartz grains. All VTL glowcurves of as-received samples did not exhibit peaks
Ketan Shah - One of the best experts on this subject based on the ideXlab platform.
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optimising volumetric arc radiotherapy for dental rehabilitation in oropharynx cancer a Retrospective Dosimetry review and feasibility planning study
Oral Oncology, 2018Co-Authors: Sean M Ocathail, Naveen Karir, Ketan ShahAbstract:Abstract Purpose To assess the Dosimetry to dentally relevant substructures within the mandible/maxilla, establish the predictors of increased mean anterior mandible dose and assess the feasibility of rationale optimisation of dose to the anterior mandible (AM) volume to aid reconstructive dental surgery planning, where the AM is a critical structure. Materials and methods In a cohort of radically treated oropharynx cancer patients we conducted a Retrospective Dosimetry analysis of mandible/maxilla volumes, created using a published atlas. Comparisons of mean AM dose and clinical parameters between groups were tested using Wilcoxon rank-sum and Kruskal-Wallis tests. A multivariate linear regression model was created to assess independent predictors of increased mean AM dose. Patients with a mean AM dose over 37.5 Gy were included in feasibility planning study to test the hypothesis that it is possible to safely limit the dose whilst maintaining dose tolerances for other organs at risk. Results 57 patients were included. Median AM mean dose was 32.2 Gy (IQR 27.7–38.7). T stage, N stage and inclusion of Level 1B were significantly associated with increased mean AM dose. Only T stage (p = .0132) and Level Ib inclusion (p = .018) remained significant in the linear regression model. 88% of plans, all of which included Level Ib, were successfully re-optimised without breaching accepted constraints. Conclusions Oropharynx cancer patients with advanced T stage and who require Level Ib treatment receive increased mean AM dose, potentially limiting surgical dental rehabilitation options. The majority of patients can be optimised safely with appropriate AM contouring.
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Optimising volumetric arc radiotherapy for dental rehabilitation in oropharynx cancer – A Retrospective Dosimetry review and feasibility planning study
Oral oncology, 2017Co-Authors: Sean M. O’cathail, Naveen Karir, Ketan ShahAbstract:Abstract Purpose To assess the Dosimetry to dentally relevant substructures within the mandible/maxilla, establish the predictors of increased mean anterior mandible dose and assess the feasibility of rationale optimisation of dose to the anterior mandible (AM) volume to aid reconstructive dental surgery planning, where the AM is a critical structure. Materials and methods In a cohort of radically treated oropharynx cancer patients we conducted a Retrospective Dosimetry analysis of mandible/maxilla volumes, created using a published atlas. Comparisons of mean AM dose and clinical parameters between groups were tested using Wilcoxon rank-sum and Kruskal-Wallis tests. A multivariate linear regression model was created to assess independent predictors of increased mean AM dose. Patients with a mean AM dose over 37.5 Gy were included in feasibility planning study to test the hypothesis that it is possible to safely limit the dose whilst maintaining dose tolerances for other organs at risk. Results 57 patients were included. Median AM mean dose was 32.2 Gy (IQR 27.7–38.7). T stage, N stage and inclusion of Level 1B were significantly associated with increased mean AM dose. Only T stage (p = .0132) and Level Ib inclusion (p = .018) remained significant in the linear regression model. 88% of plans, all of which included Level Ib, were successfully re-optimised without breaching accepted constraints. Conclusions Oropharynx cancer patients with advanced T stage and who require Level Ib treatment receive increased mean AM dose, potentially limiting surgical dental rehabilitation options. The majority of patients can be optimised safely with appropriate AM contouring.
Christopher Raaf - One of the best experts on this subject based on the ideXlab platform.
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the 2019 2020 eurados wg10 and reneb field test of Retrospective Dosimetry methods in a small scale incident involving ionizing radiation
Radiation Research, 2020Co-Authors: Lovisa Waldner, Christian Bernhardsson, Christopher Raaf, C. Woda, C. Bassinet, F. Trompier, Ulrike Kulka, Ursula Oestreicher, O Van Hoey, Michael DischerAbstract:With the use of ionizing radiation comes the risk of accidents and malevolent misuse. When unplanned exposures occur, there are several methods which can be used to Retrospectively reconstruct individual radiation exposures; biological methods include analysis of aberrations and damage of chromosomes and DNA, while physical methods rely on luminescence (TL/OSL) or EPR signals. To ensure the quality and dependability of these methods, they should be evaluated under realistic exposure conditions. In 2019, EURADOS Working Group 10 and RENEB organized a field test with the purpose of evaluating Retrospective Dosimetry methods as carried out in potential real-life exposure scenarios. A 1.36 TBq 192Ir source was used to irradiate anthropomorphic phantoms in different geometries at doses of several Gy in an outdoor open-air geometry. Materials intended for accident Dosimetry (including mobile phones and blood) were placed on the phantoms together with reference dosimeters (LiF, NaCl, glass). The objective was to estimate radiation exposures received by individuals as measured using blood and fortuitous materials, and to evaluate these methods by comparing the estimated doses to reference measurements and Monte Carlo simulations. Herein we describe the overall planning, goals, execution and preliminary outcomes of the 2019 field test. Such field tests are essential for the development of new and existing methods. The outputs from this field test include useful experience in terms of planning and execution of future exercises, with respect to time management, radiation protection, and reference Dosimetry to be considered to obtain relevant data for analysis.
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desiccants for Retrospective Dosimetry using optically stimulated luminescence osl
Radiation Measurements, 2015Co-Authors: Therese Geber, Christian Bernhardsson, Maria Christiansson, Soren Mattsson, Christopher RaafAbstract: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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Using an optimised OSL single-aliquot regenerative-dose protocol for low-dose Retrospective Dosimetry on household salt.
Radiation protection dosimetry, 2011Co-Authors: Maria Christiansson, Christian Bernhardsson, Soren Mattsson, Christopher RaafAbstract: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. (Less)
Christian Bernhardsson - One of the best experts on this subject based on the ideXlab platform.
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the 2019 2020 eurados wg10 and reneb field test of Retrospective Dosimetry methods in a small scale incident involving ionizing radiation
Radiation Research, 2020Co-Authors: Lovisa Waldner, Christian Bernhardsson, Christopher Raaf, C. Woda, C. Bassinet, F. Trompier, Ulrike Kulka, Ursula Oestreicher, O Van Hoey, Michael DischerAbstract:With the use of ionizing radiation comes the risk of accidents and malevolent misuse. When unplanned exposures occur, there are several methods which can be used to Retrospectively reconstruct individual radiation exposures; biological methods include analysis of aberrations and damage of chromosomes and DNA, while physical methods rely on luminescence (TL/OSL) or EPR signals. To ensure the quality and dependability of these methods, they should be evaluated under realistic exposure conditions. In 2019, EURADOS Working Group 10 and RENEB organized a field test with the purpose of evaluating Retrospective Dosimetry methods as carried out in potential real-life exposure scenarios. A 1.36 TBq 192Ir source was used to irradiate anthropomorphic phantoms in different geometries at doses of several Gy in an outdoor open-air geometry. Materials intended for accident Dosimetry (including mobile phones and blood) were placed on the phantoms together with reference dosimeters (LiF, NaCl, glass). The objective was to estimate radiation exposures received by individuals as measured using blood and fortuitous materials, and to evaluate these methods by comparing the estimated doses to reference measurements and Monte Carlo simulations. Herein we describe the overall planning, goals, execution and preliminary outcomes of the 2019 field test. Such field tests are essential for the development of new and existing methods. The outputs from this field test include useful experience in terms of planning and execution of future exercises, with respect to time management, radiation protection, and reference Dosimetry to be considered to obtain relevant data for analysis.
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desiccants for Retrospective Dosimetry using optically stimulated luminescence osl
Radiation Measurements, 2015Co-Authors: Therese Geber, Christian Bernhardsson, Maria Christiansson, Soren Mattsson, Christopher RaafAbstract: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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Retrospective Dosimetry using OSL of tooth enamel and dental repair materials irradiated under wet and dry conditions
Radiation and Environmental Biophysics, 2012Co-Authors: Therése Geber-bergstrand, Christian Bernhardsson, Soren Mattsson, Christopher L. RääfAbstract: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 ^90Sr/^90Y 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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Using an optimised OSL single-aliquot regenerative-dose protocol for low-dose Retrospective Dosimetry on household salt.
Radiation protection dosimetry, 2011Co-Authors: Maria Christiansson, Christian Bernhardsson, Soren Mattsson, Christopher RaafAbstract: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. (Less)