Review of retrospective dosimetry techniques for external ionising radiation exposures
Health Protection Agency1, Autonomous University of Barcelona2, Istituto Nazionale di Fisica Nucleare3, University of Palermo4, Leiden University5, Istituto Superiore di Sanità6, Institut de radioprotection et de sûreté nucléaire7, Norwegian Radiation Protection Authority8, Radiation and Nuclear Safety Authority9, Ghent University10, Stockholm University11
TL;DR: In this article, established and emerging dosimetry methods are reviewed, which can be used immediately and retrospectively following external ionising radiation exposure, and individual characteristics of these techniques, their limitations and potential for further development are discussed, and their usefulness in specific exposure scenarios is discussed.
Abstract: The current focus on networking and mutual assistance in the management of radiation accidents or incidents has demonstrated the importance of a joined-up approach in physical and biological dosimetry. To this end, the European Radiation Dosimetry Working Group 10 on 'Retrospective Dosimetry' has been set up by individuals from a wide range of disciplines across Europe. Here, established and emerging dosimetry methods are reviewed, which can be used immediately and retrospectively following external ionising radiation exposure. Endpoints and assays include dicentrics, translocations, premature chromosome condensation, micronuclei, somatic mutations, gene expression, electron paramagnetic resonance, thermoluminescence, optically stimulated luminescence, neutron activation, haematology, protein biomarkers and analytical dose reconstruction. Individual characteristics of these techniques, their limitations and potential for further development are reviewed, and their usefulness in specific exposure scenarios is discussed. Whilst no single technique fulfils the criteria of an ideal dosemeter, an integrated approach using multiple techniques tailored to the exposure scenario can cover most requirements.
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Barcelona Biomedical Research Park1, Curie Institute2, Ghent University3, Institut de radioprotection et de sûreté nucléaire4, Health Protection Agency5, Stockholm University6, University of Sussex7, Radiation and Nuclear Safety Authority8, French Alternative Energies and Atomic Energy Commission9, French Institute of Health and Medical Research10
TL;DR: This review summarises the multidisciplinary work undertaken in the framework of the European project DoReMi (Low Dose Research towards Multidisciplinary Integration) to identify the most appropriate biomarkers for use in population studies and proposes a temporal classification of biomarkers that may be relevant for molecular epidemiology studies which need to take into account the time elapsed since exposure.
Abstract: Ionizing radiation is a known human carcinogen that can induce a variety of biological effects depending on the physical nature, duration, doses and dose-rates of exposure. However, the magnitude of health risks at low doses and dose-rates (below 100 mSv and/or 0.1 mSv min−1) remains controversial due to a lack of direct human evidence. It is anticipated that significant insights will emerge from the integration of epidemiological and biological research, made possible by molecular epidemiology studies incorporating biomarkers and bioassays. A number of these have been used to investigate exposure, effects and susceptibility to ionizing radiation, albeit often at higher doses and dose rates, with each reflecting time-limited cellular or physiological alterations. This review summarises the multidisciplinary work undertaken in the framework of the European project DoReMi (Low Dose Research towards Multidisciplinary Integration) to identify the most appropriate biomarkers for use in population studies. In addition to logistical and ethical considerations for conducting large-scale epidemiological studies, we discuss the relevance of their use for assessing the effects of low dose ionizing radiation exposure at the cellular and physiological level. We also propose a temporal classification of biomarkers that may be relevant for molecular epidemiology studies which need to take into account the time elapsed since exposure. Finally, the integration of biology with epidemiology requires careful planning and enhanced discussions between the epidemiology, biology and dosimetry communities in order to determine the most important questions to be addressed in light of pragmatic considerations including the appropriate population to be investigated (occupationally, environmentally or medically exposed), and study design. The consideration of the logistics of biological sample collection, processing and storing and the choice of biomarker or bioassay, as well as awareness of potential confounding factors, are also essential.
182 citations
TL;DR: As part of the national preparedness and planning for a nuclear or radiological incident, the authors reviewed the primary literature to determine the capabilities and limitations of a number of biodosimetry assays currently available or under development for use in the initial and secondary triage of patients.
Abstract: Following a mass-casualty nuclear disaster, effective medical triage has the potential to save tens of thousands of lives. In order to best use the available scarce resources, there is an urgent need for biodosimetry tools to determine an individual's radiation dose. Initial triage for radiation exposure will include location during the incident, symptoms, and physical examination. Stepwise triage will include point of care assessment of less than or greater than 2 Gy, followed by secondary assessment, possibly with high throughput screening, to further define an individual's dose. Given the multisystem nature of radiation injury, it is unlikely that any single biodosimetry assay can be used as a standalone tool to meet the surge in capacity with the timeliness and accuracy needed. As part of the national preparedness and planning for a nuclear or radiological incident, the authors reviewed the primary literature to determine the capabilities and limitations of a number of biodosimetry assays currently available or under development for use in the initial and secondary triage of patients. Understanding the requirements from a response standpoint and the capability and logistics for the various assays will help inform future biodosimetry technology development and acquisition. Factors considered include: type of sample required, dose detection limit, time interval when the assay is feasible biologically, time for sample preparation and analysis, ease of use, logistical requirements, potential throughput, point-of-care capability, and the ability to support patient diagnosis and treatment within a therapeutically relevant time point.
145 citations
Cites background or methods from "Review of retrospective dosimetry t..."
...At this time, ISO standardization is in progress for this method (Ainsbury et al. 2011)....
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...The LDK assay is useful for estimating preliminary doses in the range of approximately 0.5Y10 Gy (Goans et al. 1997, 2001; Dainiak 2002; Waselenko et al. 2004; Blakely et al. 2005; Goans and Waselenko 2005; HPA 2009; Ainsbury et al. 2011)....
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...Lymphocyte depletion in the peripheral blood can occur after exposure to a radiation dose above 0.5 Gy with an exponential decline in lymphocytes occurring 12 or more hours after exposure (Goans et al. 2001; Azizova et al. 2008; Ainsbury et al. 2011)....
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TL;DR: Measurements of γ-H2AX immunofluorescence by microscopy and flow cytometry enables rapid and accurate assessment of whole body doses while dispersion analysis of foci or intensity distributions helps determine partial body doses and the irradiated fraction size in cases of partial body exposures.
Abstract: Most human exposures to ionising radiation are partial body exposures. However, to date only limited tools are available for rapid and accurate estimation of the dose distribution and the extent of the body spared from the exposure. These parameters are of great importance for emergency triage and clinical management of exposed individuals. Here, measurements of γ-H2AX immunofluorescence by microscopy and flow cytometry were compared as rapid biodosimetric tools for whole and partial body exposures. Ex vivo uniformly X-irradiated blood lymphocytes from one donor were used to generate a universal biexponential calibration function for γ-H2AX foci/intensity yields per unit dose for time points up to 96 hours post exposure. Foci – but not intensity – levels remained significantly above background for 96 hours for doses of 0.5 Gy or more. Foci-based dose estimates for ex vivo X-irradiated blood samples from 13 volunteers were in excellent agreement with the actual dose delivered to the targeted samples. Flow cytometric dose estimates for X-irradiated blood samples from 8 volunteers were in excellent agreement with the actual dose delivered at 1 hour post exposure but less so at 24 hours post exposure. In partial body exposures, simulated by mixing ex vivo irradiated and unirradiated lymphocytes, foci/intensity distributions were significantly over-dispersed compared to uniformly irradiated lymphocytes. For both methods and in all cases the estimated fraction of irradiated lymphocytes and dose to that fraction, calculated using the zero contaminated Poisson test and γ-H2AX calibration function, were in good agreement with the actual mixing ratios and doses delivered to the samples. In conclusion, γ-H2AX analysis of irradiated lymphocytes enables rapid and accurate assessment of whole body doses while dispersion analysis of foci or intensity distributions helps determine partial body doses and the irradiated fraction size in cases of partial body exposures.
143 citations
Cites background from "Review of retrospective dosimetry t..."
...Dose assessments based on well established cytogenetic assays and especially those utilising emerging techniques in the field of biological dosimetry are mainly suited for whole body exposures to ionising radiation [1]....
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TL;DR: The DCA has been confirmed as the gold standard biodosimetry method, but in situations where speed and throughput are more important than ultimate accuracy, the emerging rapid molecular assays have the potential to become useful triage tools.
Abstract: Rapid biodosimetry tools are required to assist with triage in the case of a large-scale radiation incident. Here, we aimed to determine the dose-assessment accuracy of the well-established dicentric chromosome assay (DCA) and cytokinesis-block micronucleus assay (CBMN) in comparison to the emerging γ-H2AX foci and gene expression assays for triage mode biodosimetry and radiation injury assessment. Coded blood samples exposed to 10 X-ray doses (240 kVp, 1 Gy/min) of up to 6.4 Gy were sent to participants for dose estimation. Report times were documented for each laboratory and assay. The mean absolute difference (MAD) of estimated doses relative to the true doses was calculated. We also merged doses into binary dose categories of clinical relevance and examined accuracy, sensitivity and specificity of the assays. Dose estimates were reported by the first laboratories within 0.3–0.4 days of receipt of samples for the γ-H2AX and gene expression assays compared to 2.4 and 4 days for the DCA and CBMN assays, ...
122 citations
Cites background or methods from "Review of retrospective dosimetry t..."
...Here, we have added several dimensions by (1) comparing established (DCA, CBMN) as well emerging assays (gene expression, c-H2AX foci) and one assay (H-module) dealing with estimates of hematological damage and not exposure (dose estimate), (2) allowing for both manual and automated scoring, (3) testing how the number of scored cells affects dose estimates and (4) by timing the delivery of dose estimates....
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...In contrast to the typical scenario of a radiation incident that affects only a few individuals, rapid tools are required in the case of large-scale accidental exposure or deliberate radiation exposure to (1) help identify the few severely exposed individuals who may require clinical monitoring and treatment and (2) reassure the many ‘‘worried-well’’, to prevent them from overwhelming emergency responders and healthcare infrastructure (5, 6)....
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...The main focus for such isolated cases is to provide the most accurate dose estimate, taking into account exposure characteristics such as radiation type and quality as well as uniformity, duration and timing of the exposure (1, 2)....
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...Several different approaches have been or are currently being implemented to address the capacity gap: triage mode scoring for the dicentric assay (7, 8), ‘‘QuickScan’’ dicentric chromosome analysis (9), networking between biodosimetry laboratories (10–16), telescoring (17), automation (18, 19) and the development of novel assays that have the potential for quicker reporting times and higher throughput than the established cytogenetic methods (1, 2)....
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TL;DR: This minireview focuses on the position of MN among the other genotoxicity tests, its usefulness in different applications and visibility by international organizations, and the mechanism of micronuclei formation.
Abstract: During almost 40 years of use, the micronucleus assay (MN) has become one of the most popular methods to assess genotoxicity of different chemical and physical factors, including ionizing radiation-induced DNA damage. In this minireview, we focus on the position of MN among the other genotoxicity tests, its usefulness in different applications and visibility by international organizations, such as International Atomic Energy Agency, Organization for Economic Co-operation and Development and International Organization for Standardization. In addition, the mechanism of micronuclei formation is discussed. Finally, foreseen directions of the MN development are pointed, such as automation, buccal cells MN and chromothripsis phenomenon.
112 citations
Cites background or methods from "Review of retrospective dosimetry t..."
...In this regard, the most commonly used technique is the dicentric chromosome assay due to its high specificity for radiation, but CBMN is also often used, less specific, but easier to perform, faster and easy to automatize [21,23]....
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...Knowing the frequency of changes in genetic material, it is possible to estimate the extent of exposure or even to reconstruct an absorbed dose of ionizing radiation [21,22]....
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...The IAEA has always considered biological dosimetry, including MN, as an important component of the radiation protection system....
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...Abbreviations BMn Buccal cells micronucleus assay; CBMN Cytokinesis-block micronucleus assay; CRA Coordinated Research Activities; DB Double minutes; EMn Mammalian erythrocyte micronucleus assay; HUMN International Human Micronucleus Project; IAEA International Atomic Energy Agency ISO International Organization for Standardization; IR Ionizing radiation; Mn Micronucleus, micronuclei; MN Micronucleus assay; OECD The Organization for Economic Co-operation and Development; RENEB Running the European Network of Biological and retrospective Physical dosimetry RT Radiation therapy, radiotherapy;...
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...The IAEA supports the development and sustainability of biological dosimetry methods in member states counties....
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References
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TL;DR: Criteria for scoring micron nuclei and nucleoplasmic bridges in binucleated cells in the cytokinesis-block micronucleus assay for isolated human lymphocyte cultures are described in detail and will assist in the development of a procedure for calibrating scorers and laboratories so that results from different laboratories may be more comparable in the future.
Abstract: Criteria for scoring micronuclei and nucleoplasmic bridges in binucleated cells in the cytokinesis-block micronucleus assay for isolated human lymphocyte cultures are described in detail. Morphological characteristics of mononucleated cells, binucleated cells, and multinucleated cells as well as necrotic and apoptotic cells and nuclear buds are also described. These criteria are illustrated by a series of schematic diagrams as well as a comprehensive set of colour photographs that are of practical assistance during the scoring of slides. These scoring criteria, diagrams and photographs have been used in a HUman MicronNucleus (HUMN) project inter-laboratory slide-scoring exercise to evaluate the extent of variability that can be attributable to individual scorers and individual laboratories when measuring the frequency of micronuclei and nucleoplasmic bridges in binucleated cells as well as the nuclear division index. The results of the latter study are described in an accompanying paper. It is expected that these scoring criteria will assist in the development of a procedure for calibrating scorers and laboratories so that results from different laboratories for the cytokinesis-block micronucleus assay may be more comparable in the future.
1,231 citations
TL;DR: The versatility and simplicity of the CBMN assay together with new developments in automation should ensure its successful application in monitoring exposed populations as well as in identifying mutagen-sensitive individuals within a population.
Abstract: The development of the cytokinesis-block (CB) technique has transformed the human-lymphocyte micronucleus assay (MN) into a reliable and precise method for assessing chromosome damage. Recent studies in our laboratory have confirmed that this method is a sensitive indicator of in vivo radiation exposure in (a) patients undergoing fractionated partial-body radiotherapy and (b) rodents exposed to uniform whole-body irradiation, thus supporting the application of the cytokinesis-block micronucleus (CBMN) assay for biological dosimetry. To further define the use of this assay in biomonitoring we performed extensive studies to determine the spontaneous level of MN in normal human populations and its relationship to various life-style factors. We have also developed a new variation to the CBMN assay that permits the conversion of excision-repairable lesions to MN within one cell-cycle using cytosine arabinoside. With this method the slope of the in vitro dose-response curves was increased by a factor of 1.8 for X-rays, 10.3 for ultraviolet (UV, 254 nm) radiation and approximately 40-fold for methylnitrosourea. Consequently the CBMN assay can now be used to measure not only whole chromosome loss or chromosome breaks but also excision-repair events. The versatility and simplicity of the CBMN assay together with new developments in automation should ensure its successful application in monitoring exposed populations as well as in identifying mutagen-sensitive individuals within a population.
953 citations
"Review of retrospective dosimetry t..." refers background in this paper
...This is due to the relatively high and variable spontaneous MN yield that tends to increase with age and is more pronounced in females((13))....
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TL;DR: Results suggest that relative levels of gene expression in peripheral blood cells may provide estimates of environmental radiation exposures, and identify genes expressed at increased levels in human peripheral blood lymphocytes after ex vivo irradiation.
Abstract: Amundson, S. A., Do, K. T., Shahab, S., Bittner, M., Meltzer, P., Trent, J. and Fornace, A. J., Jr. Identification of Potential mRNA Biomarkers in Peripheral Blood Lymphocytes for Human Exposure to Ionizing Radiation. Since early in the Atomic Age, biological indicators of radiation exposure have been sought, but currently available methods are not entirely satisfactory. Using cDNA microarray hybridization to discover new potential biomarkers, we have identified genes expressed at increased levels in human peripheral blood lymphocytes after ex vivo irradiation. We recently used this technique to identify a large set of ionizing radiation-responsive genes in a human cell line (Oncogene 18, 3666–3672, 1999). The present set of radiation markers in peripheral blood lymphocytes was identified 24 h after treatment, and while the magnitude of mRNA induction generally decreased over time, many markers were still significantly elevated up to 72 h after irradiation. In all donors, the most highly responsi...
279 citations
TL;DR: A framework for understanding how radiation levels are quantified, how radiation alters the function of hematopoietic cells and tissues, and how victims receiving a significant radiation dose can be identified and managed is provided.
Abstract: Since the terrorist attack of September 11, 2001, preparation by the health care system for an act of terrorism has been mandated by leaders of governments. Scenarios for terrorist acts involving radioactive material have been identified, and approaches to management (based on past experience from atomic weapons detonations and radiation accidents) have been developed. Because of their experience in managing patients with profound cytopenia and/or marrow aplasia, hematologists will be asked to play a significant role in evaluating and treating victims of mass accidental or deliberate exposure to radiation. This review provides a framework for understanding how radiation levels are quantified, how radiation alters the function of hematopoietic (and nonhematopoietic) cells and tissues, and how victims receiving a significant radiation dose can be identified and managed. In Section I, Dr. Nicholas Dainiak reviews four components of the Acute Radiation Syndrome: the hematopoietic, neurovascular, gastrointestinal and cutaneous subsyndromes. Clinical signs and symptoms are discussed for exposed individuals at the time of initial presentation (the prodromal phase) and during their course of disease (the manifest illness). In Section II, he presents clinical and laboratory methods to assess radiation doses, including time to onset and severity of vomiting, rate of decline in absolute blood lymphocyte count and the appearance of chromosome aberrations such as dicentrics and ring forms. Potential scenarios of a radiation terrorist event are reviewed, and methods for initial clinical assessment, triage, and early management of the acute radiation syndrome and its component subsyndromes are summarized. In Section III, Dr. Jamie Waselenko reviews the hematopoietic syndrome, and presents guidelines for the use of cytokine therapy, antibiotics, and supportive care that have been developed by the Strategic National Pharmaceutical Stockpile Working Group. Results of preclinical and clinical growth factor therapy studies with G-CSF, GM-CSF, pegylated G-CSF, SCF, and IL-3 are summarized. When and how potassium iodide should be used after exposure to radioiodines is also reviewed. In Section IV, Dr. James Armitage describes a narrow "window" of 7 to 10 Gy where therapy with stem cell transplantation may be appropriate. Victims who are candidates for allotransplantation should not have major trauma or significant injury to other (nonhematopoietic) tissues. Rarely, victims may have an identical sibling or autologous stored marrow or blood stem cells, in which case the threshold for transplantation is 4 Gy. In Section V, Dr. Thomas MacVittie describes new directions for therapy, using cytokines such as IL-7, keratinocyte growth factor, and FLT-3. The potential for combinations of cytokines to enhance hematopoietic recovery is also reviewed.
237 citations
"Review of retrospective dosimetry t..." refers background in this paper
...0 and 4–9 10(9)/l for lymphocytes and granulocytes, respectively((48))....
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TL;DR: In this article, the γH2AX (phosphorylated form of H2AX histone variant)-based visualization and quantification of DNA damage induced in peripheral blood mononuclear cells (PBMCs) can be used to estimate the radiation dose received by adult patients who undergo multidetector computed tomography (CT).
Abstract: Purpose: To prospectively determine if γH2AX (phosphorylated form of H2AX histone variant)-based visualization and quantification of DNA damage induced in peripheral blood mononuclear cells (PBMCs) can be used to estimate the radiation dose received by adult patients who undergo multidetector computed tomography (CT). Materials and Methods: After institutional review board approval and written informed patient consent were obtained, eight women and five men (mean age, 63.8 years) who would be undergoing chest-abdominal-pelvic CT or chest CT only were recruited. Venous blood samples obtained before scanning were exposed to different radiation doses in vitro and incubated for 5–30 minutes to obtain reference values of γH2AX focus yield. Additional blood samples were taken 5–30 minutes after CT. Leukocytes were isolated, fixed, and stained for γH2AX expression. The γH2AX focus yields were determined with fluorescence microscopy, and the radiation doses delivered during CT were estimated by comparing post-CT ...
211 citations