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ZusammenfassungBei einer unklaren, übermäßigen Exposition durch ionisierende Strahlung am Menschen bietet die biologische Dosimetrie die Möglichkeit, diese retrospektiv nachzuweisen und gegebenenfalls zu quantifizieren. Besonders hilfreich ist dies in Fällen, in denen keine physikalische Dosisrekonstruktion möglich ist oder widersprüchliche Ergebnisse vorliegen.Grundlage für die biologische Dosimetrie sind zelluläre Reaktionen, DNA-Schäden und Fehlreparaturen nach einer Exposition gegenüber ionisierender Strahlung. Die in der biologischen Dosimetrie eingesetzten Methoden weisen diese Veränderungen nach und setzen sie anhand von Dosis-Effekt-Kurven ins Verhältnis zur Expositionsdosis. Die Analyse von dizentrischen Chromosomen hat sich als zuverlässigste und empfindlichste Methode für den Nachweis einer Exposition mit ionisierender Strahlung erwiesen, weil sie eine niedrige spontane Häufigkeit aufweist und für ionisierende Strahlung charakteristisch ist. Die Nachweisgrenze für eine homogene Ganzkörperbestrahlung liegt bei 0,1 Gy bei der Auswertung von 500–1000 Zellen für locker ionisierende γ-Strahlung. Die Analyse erfolgt im Speziallabor nach international standardisierten Verfahren.Die biologische Dosimetrie kommt als unabhängige Methode oder zur Ergänzung der physikalischen Dosimetrie zum Einsatz. Da bei der biologischen Dosimetrie die Wirkung der Dosis im Blut erfasst wird, können wertvolle Erkenntnisse zur Strahlenexposition geliefert werden und die medizinische Versorgung von Betroffenen unterstützt werden.

In the case of a radiological or nuclear event, biological dosimetry can be an important tool to support clinical decision-making. During a nuclear event, individuals might be exposed to a mixed field of neutrons and photons. The composition of the field and the neutron energy spectrum influence the degree of damage to the chromosomes. During the transatlantic BALANCE project, an exposure similar to a Hiroshima-like device at a distance of 1.5 km from the epicenter was simulated and biological dosimetry based on dicentric chromosomes was performed to evaluate the participants ability to discover unknown doses and to test the influence of differences in neutron spectra. In a first step, calibration curves were established by irradiating blood samples with 5 doses in the range of 0 Gy to 4 Gy at two different facilities in Germany (PTB) and USA (CINF). The samples were sent to eight participating laboratories from the RENEB network and dicentric chromosomes were scored by each participant. Next, blood samples were irradiated with 4 blind doses in each of the two facilities and sent to the participants to provide dose estimates based on the established calibration curves. Manual and semi-automatic scoring of dicentric chromosomes were evaluated for their applicability to neutron exposures. Moreover, the biological effectiveness of the neutrons from the two irradiation facilities was compared. The calibration curves from samples irradiated at CINF showed a 1.4 times higher biological effectiveness compared to samples irradiated at PTB. For manual scoring of dicentric chromosomes, the doses of the test samples were mostly successfully resolved based on the calibration curves established during the project. For semi-automatic scoring, the dose estimation for the test samples was less successful. Doses >2 Gy in the calibration curves revealed non-linear associations between dose and dispersion index of the dicentric counts, especially for manual scoring. The differences in the biological effectiveness between the irradiation facilities suggested that the neutron energy spectrum can have a strong impact on the dicentric counts.

Purpose: The traditional workflow for biological dosimetry based on manual scoring of dicentric chromosomes is very time consuming. Especially for large-scale scenarios or for low-dose exposures, high cell numbers have to be analysed, requiring alternative scoring strategies. Semi-automatic scoring of dicentric chromosomes provides an opportunity to speed up the standard workflow of biological dosimetry. Due to automatic metaphase and chromosome detection, the number of counted chromosomes per metaphase is variable. This can potentially introduce overdispersion and statistical methods for conventional, manual scoring might not be applicable to data obtained by automatic scoring of dicentric chromosomes, potentially resulting in biased dose estimates and underestimated uncertainties. The identification of sources for overdispersion enables the development of methods appropriately accounting for increased dispersion levels. Materials and methods: Calibration curves based on in-vitro irradiated (137-Cs; 0.44 Gy/min) blood from three healthy donors were analysed for systematic overdispersion, especially at higher doses (> 2 Gy) of low LET radiation. For each donor, 12 doses in the range of 0-6 Gy were scored semi-automatically. The effect of chromosome number as a potential cause for the observed overdispersion was assessed. Statistical methods based on interaction models accounting for the number of detected chromosomes were developed for the estimation of calibration curves, dose and corresponding uncertainties. The dose estimation was performed based on a Bayesian Markov-Chain-Monte-Carlo method, providing high flexibility regarding the implementation of priors, likelihood and the functional form of the association between predictors and dicentric counts. The proposed methods were validated by simulations based on cross-validation. Results: Increasing dose dependent overdispersion was observed for all three donors as well as considerable differences in dicentric counts between donors. Variations in the number of detected chromosomes between metaphases were identified as a major source for the observed overdispersion and the differences between donors. Persisting overdispersion beyond the contribution of chromosome number was modelled by a Negative Binomial distribution. Results from cross-validation suggested that the proposed statistical methods for dose estimation reduced bias in dose estimates, variability between dose estimates and improved the coverage of the estimated confidence intervals. However, the 95% confidence intervals were still slightly too permissive, suggesting additional unknown sources of apparent overdispersion. Conclusions: A major source for the observed overdispersion could be identified, and statistical methods accounting for overdispersion introduced by variations in the number of detected chromosomes were developed, enabling more robust dose estimation and quantification of uncertainties or semi-automatic counting of dicentric chromosomes.

Purpose In case of a mass-casualty radiological event, there would be a need for networking to overcome surge limitations and to quickly obtain homogeneous results (reported aberration frequencies or estimated doses) among biodosimetry laboratories. These results must be consistent within such network. Inter-laboratory comparisons (ILCs) are widely accepted to achieve this homogeneity. At the European level, a great effort has been made to harmonize biological dosimetry laboratories, notably during the MULTIBIODOSE and RENEB projects. In order to continue the harmonization efforts, the RENEB consortium launched this intercomparison which is larger than the RENEB network, as it involves 38 laboratories from 21 countries. In this ILC all steps of the process were monitored, from blood shipment to dose estimation. This exercise also aimed to evaluate the statistical tools used to compare laboratory performance. Materials and methods Blood samples were irradiated at three different doses, 1.8, 0.4 and 0 Gy (samples A, C and B) with 4-MV X-rays at 0.5 Gy min-1, and sent to the participant laboratories. Each laboratory was requested to blindly analyze 500 cells per sample and to report the observed frequency of dicentric chromosomes per metaphase and the corresponding estimated dose. Results This ILC demonstrates that blood samples can be successfully distributed among laboratories worldwide to perform biological dosimetry in case of a mass casualty event. Having achieved a substantial harmonization in multiple areas among the RENEB laboratories issues were identified with the available statistical tools, which are not capable to advantageously exploit the richness of results of a large ILCs. Even though Z- and U-tests are accepted methods for biodosimetry ILCs, setting the number of analyzed metaphases to 500 and establishing a tests' common threshold for all studied doses is inappropriate for evaluating laboratory performance. Another problem highlighted by this ILC is the issue of the dose-effect curve diversity. It clearly appears that, despite the initial advantage of including the scoring specificities of each laboratory, the lack of defined criteria for assessing the robustness of each laboratory's curve is a disadvantage for the 'one curve per laboratory' model. Conclusions Based on our study, it seems relevant to develop tools better adapted to the collection and processing of results produced by the participant laboratories. We are confident that, after an initial harmonization phase reached by the RENEB laboratories, a new step toward a better optimization of the laboratory networks in biological dosimetry and associated ILC is on the way.

Purpose: Depending on the exposure scenario, different biological and/or physical assays will be required to recover the exposure situation and to obtain reliable dose estimates to aid medical decision making. Inter-laboratory comparisons (ILCs) are a central tool to validate and improve the performance of methods and laboratories. In most cases such ILCs are performed under laboratory conditions where the influence of parameters contributing to uncertainties can be minimized. In a reallife scenario, the situation is much more complicated, and it is therefore crucial to validate methods and laboratories’ abilities to carry out these methods under more realistic conditions. In 2019, EURADOS (The European Radiation Dosimetry Group) Working Group 10 (Retrospective Dosimetry) and RENEB (Running the European Network of Biological and retrospective Physical dosimetry) organized a field exercise in Lund, Sweden, to validate different methods for biological and physical retrospective dosimetry in parallel by simulating real- life exposure scenarios. Materials and methods: For the dicentric chromosome assay (DCA), 18 blood tubes were distributed across 8 thermos flasks filled with heated water and positioned at the hips and shoulders of anthropomorphic phantoms in different geometries. Two irradiations were performed with a 1.36 TBq 192Ir-source, each with two phantoms, to simulate close, distant, lateral or partially shielded exposures. For each of the blood tubes DCA dose estimates were provided by at least one laboratory and for tubes from four thermos flasks by 17 participating RENEB laboratories. In addition, blood from the different thermos flasks on each phantom was mixed to simulate heterogeneous exposures. Three radio-photoluminescence (RPL) glass dosimeters (GD) were placed at each tube to assess reference doses and the inter- and intra-tube variability. Results: The results from the DCA were homogeneous between participants and matched well with RPL GD reference doses (≥95% of estimates within ±0.5 Gy of the reference). For samples close to the source, exposed to doses >1 Gy, systematic underestimation could be corrected by accounting for exposure time. Heterogeneity within and between tubes was detected for RPL GD reference doses as well as for doses estimates from the DCA. The sample simulating a heterogeneous exposure with two different doses was detected by ~50% of the participants. Conclusions: The participants were able to successfully estimate the doses and to provide important information on the exposure scenarios under conditions closely resembling a real-life situation. The reliability of the results emphasizes the value of the DCA for retrospective dosimetry under field conditions.

International audience; With the use of ionising 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 organised 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 expose anthropomorphic phantoms in different geometries to doses of several gray 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. The aim of this paper is to 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.

Large-scale radiation emergency scenarios involving protracted low dose rate radiation exposure (e.g. a hidden radioactive source in a train) necessitate the development of high throughput methods for providing rapid individual dose estimates. During the RENEB (Running the European Network of Biodosimetry) 2019 exercise, four EDTA-blood samples were exposed to an Iridium-192 source (1.36 TBq, Tech-Ops 880 Sentinal) at varying distances and geometries. This resulted in protracted doses ranging between 0.2 and 2.4 Gy using dose rates of 1.5–40 mGy/min and exposure times of 1 or 2.5 h. Blood samples were exposed in thermo bottles that maintained temperatures between 39 and 27.7 °C. After exposure, EDTA-blood samples were transferred into PAXGene tubes to preserve RNA. RNA was isolated in one laboratory and aliquots of four blinded RNA were sent to another five teams for dose estimation based on gene expression changes. Using an X-ray machine, samples for two calibration curves (first: constant dose rate of 8.3 mGy/min and 0.5–8 h varying exposure times; second: varying dose rates of 0.5–8.3 mGy/min and 4 h exposure time) were generated for distribution. Assays were run in each laboratory according to locally established protocols using either a microarray platform (one team) or quantitative real-time PCR (qRT-PCR, five teams). The qRT-PCR measurements were highly reproducible with coefficient of variation below 15% in ≥ 75% of measurements resulting in reported dose estimates ranging between 0 and 0.5 Gy in all samples and in all laboratories. Up to twofold reductions in RNA copy numbers per degree Celsius relative to 37 °C were observed. However, when irradiating independent samples equivalent to the blinded samples but increasing the combined exposure and incubation time to 4 h at 37 °C, expected gene expression changes corresponding to the absorbed doses were observed. Clearly, time and an optimal temperature of 37 °C must be allowed for the biological response to manifest as gene expression changes prior to running the gene expression assay. In conclusion, dose reconstructions based on gene expression measurements are highly reproducible across different techniques, protocols and laboratories. Even a radiation dose of 0.25 Gy protracted over 4 h (1 mGy/min) can be identified. These results demonstrate the importance of the incubation conditions and time span between radiation exposure and measurements of gene expression changes when using this method in a field exercise or real emergency situation.

Background Mesenchymal stem cells (MSCs) are attracting increasing interest for cell-based therapies, making use of both their immuno-modulating and regenerative potential. For such therapeutic applications, a massive in vitro expansion of donor cells is usually necessary to furnish sufficient material for transplantation. It is not established to what extent the long-term genomic stability and potency of MSCs can be compromised as a result of this rapid ex vivo expansion. In this study, we investigated the DNA damage response and chromosomal stability (indicated by micronuclei induction) after sub-lethal doses of gamma irradiation in murine MSCs at different stages of their in vitro expansion. Methods Bone-marrow-derived tri-potent MSCs were explanted from 3-month-old female FVB/N mice and expanded in vitro for up to 12 weeks. DNA damage response and repair kinetics after gamma irradiation were quantified by the induction of γH2AX/53BP1 DSB repair foci. Micronuclei were counted in post-mitotic, binucleated cells using an automated image analyzer Metafer4. Involvement of DNA damage response pathways was tested using chemical ATM and DNA-PK inhibitors. Results Murine bone-marrow-derived MSCs in long-term expansion culture gradually lose their ability to recognize endogenous and radiation-induced DNA double-strand breaks. This impaired DNA damage response, indicated by a decrease in the number of γH2AX/53BP1 DSB repair foci, was associated with reduced ATM dependency of foci formation, a slower DNA repair kinetics, and an increased number of residual DNA double-strand breaks 7 h post irradiation. In parallel with this impaired efficiency of DNA break recognition and repair in older MSCs, chromosomal instability after mitosis increased significantly as shown by a higher number of micronuclei, both spontaneously and induced by γ-irradiation. Multifactorial regression analysis demonstrates that in vitro aging reduced DNA damage recognition in MSCs after irradiation by a multiplicative interaction with dose (p

Age dependent radiation sensitivity for DNA damage after in vitro blood exposure by computer tomography (CT) was investigated.Radiation biomarkers (dicentrics and gammaH2AX) in blood samples of newborns, children under five years and adults after sham exposure (0 mGy), low-dose (41 mGy) and high-dose (978 mGy) in vitro CT exposure were analyzed.Significantly higher levels of dicentric induction were found for the single and combined newborns/children group compared to adults, by a factor of 1.48 (95% CI 1.30-1.68), after exposure to 978 mGy. Although a significant dose response for damage induction and dose-dependent repair was found, the gammaH2AX assay did not show an age-dependent increase in DNA damage in newborns/children compared to adults. This was the case for the gammaH2AX levels after repair time intervals of 30 minutes and 24 hours, after correcting for the underlying background damage. For the low dose of 41 mGy, the power of the dicentric assay was also not sufficient to detect an age-dependent effect in the sample size investigated.A 1.5-fold increased level of dicentric aberrations is detected in newborns and children under five years after 1 Gy radiation exposure.

Purpose: Automated detection of dicentric chromosomes from a large number of cells was applied to study age-dependent radiosensitivity after in vitro CT exposure of blood from healthy donors. Materials and methods: Blood samples from newborns, children (2-5 years) and adults (20-50 years) were exposed in vitro to 0 mGy, 41 mGy and 978 mGy using a CT equipment. In this study, automated scoring based on 13,000-31,000 cells/dose point/age group was performed. Results for control and low dose points were validated by manually counting about 26,000 cells/dose point/age group. Results: For all age groups, the high number of analyzed cells enabled the detection of a significant increase in the frequency of radiation induced dicentric chromosomes in cells exposed to 41 mGy as compared to control cells. Moreover, differences between the age groups could be resolved for the low dose: young donors showed significantly increased risk for induced dicentrics at 41 mGy compared to adults. Conclusions: The results very clearly demonstrate that the automated dicentric scoring method is capable of discerning radiation induced biomarkers in the low dose range (

In 1983, a young man inhaled accidentally a large amount of plutonium and americium. This case was carefully followed until 2013. Since no decorporation measures had been taken, the undisturbed metabolism of Pu and Am can be derived from the data. First objective was to determine the amount of inhaled radionuclides and to estimate committed effective dose. In vivo and excretion measurements started immediately after the inhalation, and for quality assurance, all types of measurements were performed by different labs in Europe and the USA. After dose assessment by various international groups were completed, the measurements were continued to produce scientific data for model validation. The data have been analysed here to estimate lung absorption parameter values for the inhaled plutonium and americium oxide using the proposed new ICRP Human Respiratory Tract Model. As supplement to the biokinetic modelling, biological data from three different cytogenetic markers have been added. The estimated committed effective dose is in the order of 1 Sv. The subject is 30 y after the inhalation, of good health, according to a recent medical check-up.

International audience; In the event of a large-scale radiological emergency, the triage of individuals according to their degree of exposure forms an important initial step of the accident management. Although clinical signs and symptoms of a serious exposure may be used for radiological triage, they are not necessarily radiation specific and can lead to a false diagnosis. Biodosimetry is a method based on the analysis of radiation-induced changes in cells of the human body or in portable electronic devices and enables the unequivocal identification of exposed people who should receive medical treatment. The MULTIBIODOSE (MBD) consortium developed and validated several biodosimetric assays and adapted and tested them as tools for biological dose assessment in a mass-casualty event. Different biodosimetric assays were validated against the 'gold standard' of biological dosimetry-the dicentric assay. The assays were harmonised in such a way that, in an emergency situation, they can be run in parallel in a network of European laboratories. The aim of this guidance is to give a concise overview of the developed biodosimetric tools as well as how and when they can be used in an emergency situation. © The Author 2014.

Large scale radiological emergencies require high throughput techniques of biological dosimetry for population triage in order to identify individuals indicated for medical treatment. The dicentric assay is the gold standard technique for the performance of biological dosimetry, but it is very time consuming and needs well trained scorers. To increase the throughput of blood samples, semi-automation of dicentric scoring was investigated in the framework of the MULTIBIODOSE EU FP7 project, and dose effect curves were established in six biodosimetry laboratories. To validate these dose effect curves, blood samples from 33 healthy donors (>10 donors/scenario) were irradiated in vitro with Co-60 gamma rays simulating three different exposure scenarios: acute whole body, partial body, and protracted exposure, with three different doses for each scenario. All the blood samples were irradiated at Ghent University, Belgium, and then shipped blind coded to the participating laboratories. The blood samples were set up by each lab using their own standard protocols, and metaphase slides were prepared to validate the calibration curves established by semi-automatic dicentric scoring. In order to achieve this, 300 metaphases per sample were captured, and the doses were estimated using the newly formed dose effect curves. After acute uniform exposure, all laboratories were able to distinguish between 0 Gy, 0.5 Gy, 2.0, and 4.0 Gy (p < 0.001), and, in most cases, the dose estimates were within a range of +/- 0.5 Gy of the given dose. After protracted exposure, all laboratories were able to distinguish between 1.0 Gy, 2.0 Gy, and 4.0 Gy (p < 0.001), and here also a large number of the dose estimates were within +/- 0.5 Gy of the irradiation dose. After simulated partial body exposure, all laboratories were able to distinguish between 2.0 Gy, 4.0 Gy, and 6.0 Gy (p < 0.001). Overdispersion of the dicentric distribution enabled the detection of the partial body samples; however, this result was clearly dose-dependent. For partial body exposures, only a few dose estimates were in the range of +/- 0.5 Gy of the given dose, but an improvement could be achieved with higher cell numbers. The new method of semi-automation of the dicentric assay was introduced successfully in a network of six laboratories. It is therefore concluded that this method can be used as a high-throughput screening tool in a large-scale radiation accident. AuthorCount:19

Objectives This study sought to evaluate differences in radiation exposure of the operator depending on the type of catheterization lab procedure. Background Invasive cardiologists and angiologists are exposed to long-term, low-dose occupational radiation. Increased workload and specialization require more detailed knowledge of the extent and cause of the radiation exposure. Methods In this prospective single-center experience, radiation doses of 3 operators were measured by real-time dosimetry for body, neck, and hand during 284 procedures in 281 patients over a period of 14 weeks. To determine the association between the type of procedure and the doses and to draw a pairwise comparison between the procedures, 3 mixed models were used. Results The type of procedure, the patient9s body mass index, and the fluoroscopy time were independently associated with the operator9s radiation exposure. Per procedure, the operators were exposed to a mean effective dose (E) of 2.2 ± 5.9 μSv. Compared with coronary angiography, E was 2.3-fold higher in pelvic procedures (95% confidence interval [CI]: 1.7 to 3.0, p Conclusions Endovascular procedures for pelvic, upper limb, and below-the-knee disease are accompanied with a higher radiation exposure of the operator than with coronary procedures.

International audience; Purpose: RENEB, ‘Realising the European Network of Biodosimetry and Physical Retrospective Dosimetry,’ is a network for research and emergency response mutual assistance in biodosimetry within the EU. Within this extremely active network, a number of new dosimetry methods have recently been proposed or developed. There is a requirement to test and/or validate these candidate techniques and inter-comparison exercises are a well-established method for such validation. Materials and methods: The authors present details of inter-comparisons of four such new methods: dicentric chromosome analysis including telomere and centromere staining; the gene expression assay carried out in whole blood; Raman spectroscopy on blood lymphocytes, and detection of radiation-induced thermoluminescent signals in glass screens taken from mobile phones. Results: In general the results show good agreement between the laboratories and methods within the expected levels of uncertainty, and thus demonstrate that there is a lot of potential for each of the candidate techniques. Conclusions: Further work is required before the new methods can be included within the suite of reliable dosimetry methods for use by RENEB partners and others in routine and emergency response scenarios. © 2016 Crown Copyright. Published by Informa UK Limited, trading as Taylor & Francis Group.

To set up an operational basis of the Realizing the European Network of Biodosimetry (RENEB) network within which the application of seven established biodosimetric tools (the dicentric assay, the FISH assay, the micronucleus assay, the PCC assay, the gamma-H2AX assay, electron paramagnetic resonance and optically stimulated luminescence) will be compared and standardized among the participating laboratories.Two intercomparisons were organized where blood samples and smartphone components were irradiated, coded and sent out to participating laboratories for dosimetric analysis. Moreover, an accident exercise was organized during which each RENEB partner had the chance to practice the procedure of activating the network and to handle large amounts of dosimetric results.All activities were carried out as planned. Overall, the precision of dose estimates improved between intercomparisons 1 and 2, clearly showing the value of running such regular activities.The RENEB network is fully operational and ready to act in case of a major radiation emergency. Moreover, the high capacity for analyzing radiation-induced damage in cells and personal electronic devices makes the network suitable for large-scale analyses of low doses effects, where high numbers of samples must be scored in order to detect weak effects.

In the framework of RENEB, several biodosimetry exercises were conducted analyzing different endpoints. Among them, the analysis of translocations is considered the most useful method for retrospective biodosimetry due to the relative stability of their frequency with post irradiation time. The aim of this study was to harmonize the accuracy of translocation-based biodosimetry within the RENEB consortium.An initial telescoring exercise analyzing FISH metaphase images was done to harmonize chromosome aberration descriptions. Then two blind intercomparison exercises (IE) were performed, by sending irradiated blood samples to each partner. Samples were cultured and stained by each partner using their standard protocol and translocation frequency was used to produce dose estimates.The coefficient of variation in the 1st IE (CV = 0.34) was higher than in the 2nd IE (CV = 0.16 and 0.23 in the two samples analyzed), for the genomic frequency of total translocations. Z-score analysis revealed that eight out of 10 and 17 out of 20 dose estimates were satisfactory in the 1st and 2nd IE, respectively.The results obtained indicate that, despite the problems identified in few partners, which can be corrected, the RENEB consortium is able to carry out retrospective biodosimetry analyzing the frequency of translocations by FISH.

The European Network of Biological and Physical Retrospective Dosimetry 'RENEB' has contributed to European radiation emergency preparedness. To give homogeneous dose estimation results, RENEB partners must harmonize their processes.A first inter-comparison focused on biological and physical dosimetry was used to detect the outliers in terms of dose estimation. Subsequently, trainings were organized to improve both tools dose estimation. A second inter-comparison was performed to validate training efficiency. Simultaneously, based on ISO standards, a QAQM manual on all dosimetry assays was produced which states a common basis and harmonized procedures for each assay. The evaluation of the agreement of RENEB partners to follow the QAQM manual was performed through a questionnaire. The integration of new members into the network was carried out in the same way, whatever the assays.The training courses on biological and physical dosimetry were judged to be successful because most of the RENEB members' dose estimates improved in the second inter-comparison. The QAQM manual describes the consensus for the minimum requirements and the performance criteria for both dosimetry assays. The questionnaire revealed that the whole network capacity currently can manage between 15 and 3800 samples once.The methodology used to harmonize all dosimetry practice within the network RENEB was highly successful. The network is operational to manage a mass casualty radiation accident for immediate dose assessment.

Radiation accidents with exposure of human beings can assume huge dimensions concerning occurring health impairments and essential medical resources such as personnel, patient care management and appropriate medical facilities. Particularly in mass-casualty events, a rapid sorting and allocation of victims to treatment is needed and their classification in medical treatment groups has to be conducted as fast as possible. For triage purposes several approaches can be considered. Clinical signs and symptoms are extremely helpful in estimating radiation effects on an organ-based level, whereas the assessment of radiation effects based on cytogenetic biodosimetry tools is the alternative approach. For both systems there are pros and cons with respect to the usefulness for specific applications, such as individual cases versus mass-casualty screening or whole- versus partial-body exposures. Among the biodosimetry tools the dicentric chromosome assay (DCA) is considered as the “gold standard” for biodosimetry after an acute radiation exposure. Recently, steady progress in standardization and harmonization of the DCA has occurred, in order to enable the validated performance of the DCA in the frame of cooperative response of biodosimetry networks during a large scale radiological scenario. Using the DCA in triage mode which allows the stratification of radiation exposed victims into broad 1.0 Gy categories only 20–50 metaphase cells per subject are scored instead of the 500–1000 scored for routine analysis. Our data show that there are significant differences between the dicentric yields after 1.0 Gy and 3.0 Gy γ-ray ex vivo exposure of blood suggesting this assay as suitable for the distinction between high and low dosed exposed individuals. These preliminary findings indicate the usefulness of the DCA also for therapeutic decision making.

Biological dosimetry is an essential tool for estimating radiation doses received to personnel when physical dosimetry is not available or inadequate. The current preferred biodosimetry method is based on the measurement of radiation-specific dicentric chromosomes in exposed individuals' peripheral blood lymphocytes. However, this method is labour-, time- and expertise-demanding. Consequently, for mass casualty applications, strategies have been developed to increase its throughput. One such strategy is to develop validated cytogenetic biodosimetry laboratory networks, both national and international. In a previous study, the dicentric chromosome assay (DCA) was validated in our cytogenetic biodosimetry network involving five geographically dispersed laboratories. A complementary strategy to further enhance the throughput of the DCA among inter-laboratory networks is to use a triage DCA where dose assessments are made by truncating the labour-demanding and time-consuming metaphase-spread analysis to 20 to 50 metaphase spreads instead of routine 500 to 1000 metaphase spread analysis. Our laboratory network also validated this triage DCA, however, these dose estimates were made using calibration curves generated in each laboratory from the blood samples irradiated in a single laboratory. In an emergency situation, dose estimates made using pre-existing calibration curves which may vary according to radiation type and dose rate and therefore influence the assessed dose. Here, we analyze the effect of using a pre-existing calibration curve on assessed dose among our network laboratories. The dose estimates were made by analyzing 1000 metaphase spreads as well as triage quality scoring and compared to actual physical doses applied to the samples for validation. The dose estimates in the laboratory partners were in good agreement with the applied physical doses and determined to be adequate for guidance in the treatment of acute radiation syndrome.

Introduction In the framework of the RENEB project, two intercomparison exercises were conducted to assess the suitability of the cytokinesis-block micronucleus assay, and to evaluate the capacity of a large laboratory network performing biodosimetry for radiation emergency triages. Twelve European institutions participated in the first exercise, and four non-RENEB labs were added in the second one. Materials and methods Irradiated blood samples were shipped to participating labs, whose task was to culture these samples and provide a blind dose estimate. Micronucleus analysis was performed by automated, semi-automated and manual scoring procedures. Results The dose estimates provided by the network laboratories were in good agreement with the true administered doses. The most accurate estimates were reported for the low dose points ( 1 Gy). For higher dose points ( > 2.5 Gy) a larger variation in estimates was observed, though in the second exercise the number of acceptable estimates increased satisfactorily. Higher accuracy was achieved with the semi-automated method. Conclusion The results of the two intercomparsion exercises performed by our network demonstrate that the micronucleus assay is a useful tool for large-scale radiation emergencies, and can be successfully implemented within a large network of laboratories. The results further emphasize the importance of performing regular intercomparison training exercises within a specialised biodosimetry network.

Creating a sustainable network in biological and retrospective dosimetry that involves a large number of experienced laboratories throughout the European Union (EU) will significantly improve the accident and emergency response capabilities in case of a large-scale radiological emergency. A well-organised cooperative action involving EU laboratories will offer the best chance for fast and trustworthy dose assessments that are urgently needed in an emergency situation. To this end, the EC supports the establishment of a European network in biological dosimetry (RENEB). The RENEB project started in January 2012 involving cooperation of 23 organisations from 16 European countries. The purpose of RENEB is to increase the biodosimetry capacities in case of large-scale radiological emergency scenarios. The progress of the project since its inception is presented, comprising the consolidation process of the network with its operational platform, intercomparison exercises, training activities, proceedings in quality assurance and horizon scanning for new methods and partners. Additionally, the benefit of the network for the radiation research community as a whole is addressed.

Within the EU MULTIBIODOSE project, the automated micronucleus (MN) assay was optimised for population triage in large-scale radiological emergencies. For MN scoring, two approaches were applied using the Metafer4 platform (MetaSystems, Germany): fully automated scoring and semi-automated scoring with visual inspection of the gallery of MN-positive objects. Dose-response curves were established for acute and protracted whole-body and partial-body exposures. A database of background MN yields was set up, allowing determination of the dose detection threshold in both scoring modes. An analysis of the overdispersion of the MN frequency distribution sigma(2)/A mu obtained by semi-automated scoring showed that the value of this parameter represents a reliability check of the calculated equivalent total body dose in case the accident overexposure is a partial-body exposure. The elaborated methodology was validated in an accident training exercise. Overall, the semi-automated scoring procedure represents important added value to the automated MN assay.

Response to a large-scale radiological incident could require timely medical interventions to minimize radiation casualties. Proper medical care requires knowing the victim's radiation dose. When physical dosimetry is absent, radiation-specific chromosome aberration analysis can serve to estimate the absorbed dose in order to assist physicians in the medical management of radiation injuries. A mock exercise scenario was presented to six participating biodosimetry laboratories as one individual acutely exposed to Co under conditions suggesting whole-body exposure. The individual was not wearing a dosimeter and within 2-3 h of the incident began vomiting. The individual also had other medical symptoms indicating likelihood of a significant dose. Physicians managing the patient requested a dose estimate in order to develop a treatment plan. Participating laboratories in North and South America, Europe, and Asia were asked to evaluate more than 800 electronic images of metaphase cells from the patient to determine the dicentric yield and calculate a dose estimate with 95% confidence limits. All participants were blind to the physical dose until after submitting their estimates based on the dicentric chromosome assay (DCA). The exercise was successful since the mean biological dose estimate was 1.89 Gy whereas the actual physical dose was 2 Gy. This is well within the requirements for guidance of medical management. The exercise demonstrated that the most labor-intensive step in the entire process (visual evaluation of images) can be accelerated by taking advantage of world-wide expertise available on the Internet.

International audience; Purpose The European Union's Seventh Framework Programme-funded project 'Multi-disciplinary biodosimetric tools to manage high scale radiological casualties' (MULTIBIODOSE) has developed a multiparametric approach to radiation biodosimetry, with a particular emphasis on triage of large numbers of potentially exposed individuals following accidental exposures. In November 2012, an emergency exercise took place which tested the capabilities of the MULTIBIODOSE project partners. The exercise described here had a dual purpose Intercomparison of (i) three biodosimetric assays, and (ii) the capabilities of the seven laboratories, with regards to provision of triage status for suspected radiation exposed individuals. Materials and methods Three biological dosimetry tools-the dicentric, micronucleus and gamma-H2AX (the phosphorylated form of member X of histone H2A, in response to DNA double-strand breaks) foci assays-were tested, in addition to provision of the triage status results (low exposure < 1 Gy; medium exposure 1-2 Gy; high exposure > 2 Gy) by the MULTIBIODOSE software. The exercise was run in two modes An initial triage categorisation of samples (based on the first dose estimates for each assay received from each laboratory) followed by collation of the full set of estimated doses (all the results from all modes of each assay carried out by the participating laboratories) calculated using as many modes of operation as possible of the different assays developed during the project. Simulated acute whole body and partial body exposures were included. Results The results of the initial triage categorisation and the full comparison of assays and methods within and between laboratories are presented here. Conclusions The data demonstrate that the MULTIBIODOSE approach of applying multiparametric tools to radiation emergencies is valid and effective. © 2014 Informa UK, Ltd.

The focus of the study is an intercomparison of laboratories' dose-assessment performances using the cytokinesis-block micronucleus (CBMN) assay as a diagnostic triage tool for individual radiation dose assessment. Homogenously X-irradiated (240 kVp, 1 Gy/min) blood samples for establishing calibration data (0.25-5 Gy) as well as blind samples (0.1-6.4 Gy) were sent to the participants. The CBMN assay was performed according to protocols individually established and varying among participating laboratories. The time taken to report dose estimates was documented for each laboratory. Additional information concerning laboratory organization/characteristics as well as assay performance was collected. The mean absolute difference (MAD) was calculated and radiation doses were merged into four triage categories reflecting clinical aspects to calculate accuracy, sensitivity and specificity. The earliest report time was 4 days after sample arrival. The CBMN dose estimates were reported with high accuracy (MAD values of 0.20-0.50 Gy at doses below 6.4 Gy for both manual and automated scoring procedures), but showed a limitation of the assay at the dose point of 6.4 Gy, which resulted in a clear dose underestimation in all cases. The MAD values (without 6.4 Gy) differed significantly (P = 0.03) between manual (0.25 Gy, SEM = 0.06, n = 4) or automated scoring procedures (0.37 Gy, SEM = 0.08, n = 5), but lowest MAD were equal (0.2 Gy) for both scoring procedures. Likewise, both scoring procedures led to the same allocation of dose estimates to triage categories of clinical significance (about 83% accuracy and up to 100% specificity).

International audience; Mass casualty scenarios of radiation exposure require high throughput biological dosimetry techniques for population triage in order to rapidly identify individuals who require clinical treatment. The manual dicentric assay is a highly suitable technique, but it is also very time consuming and requires well trained scorers. In the framework of the MULTIBIODOSE EU FP7 project, semi-automated dicentric scoring has been established in six European biodosimetry laboratories. Whole blood was irradiated with a Co-60 gamma source resulting in 8 different doses between 0 and 4.5. Gy and then shipped to the six participating laboratories. To investigate two different scoring strategies, cell cultures were set up with short term (2-3. h) or long term (24. h) colcemid treatment. Three classifiers for automatic dicentric detection were applied, two of which were developed specifically for these two different culture techniques. The automation procedure included metaphase finding, capture of cells at high resolution and detection of dicentric candidates. The automatically detected dicentric candidates were then evaluated by a trained human scorer, which led to the term 'semi-automated' being applied to the analysis. The six participating laboratories established at least one semi-automated calibration curve each, using the appropriate classifier for their colcemid treatment time. There was no significant difference between the calibration curves established, regardless of the classifier used. The ratio of false positive to true positive dicentric candidates was dose dependent. The total staff effort required for analysing 150 metaphases using the semi-automated approach was 2. min as opposed to 60. min for manual scoring of 50 metaphases. Semi-automated dicentric scoring is a useful tool in a large scale radiation accident as it enables high throughput screening of samples for fast triage of potentially exposed individuals. Furthermore, the results from the participating laboratories were comparable which supports networking between laboratories for this assay. © 2013 Elsevier B.V.

This study sought to evaluate differences in radiation exposure of the operator depending on the type of catheterization lab procedure.Invasive cardiologists and angiologists are exposed to long-term, low-dose occupational radiation. Increased workload and specialization require more detailed knowledge of the extent and cause of the radiation exposure.In this prospective single-center experience, radiation doses of 3 operators were measured by real-time dosimetry for body, neck, and hand during 284 procedures in 281 patients over a period of 14 weeks. To determine the association between the type of procedure and the doses and to draw a pairwise comparison between the procedures, 3 mixed models were used.The type of procedure, the patient's body mass index, and the fluoroscopy time were independently associated with the operator's radiation exposure. Per procedure, the operators were exposed to a mean effective dose (E) of 2.2 ± 5.9 μSv. Compared with coronary angiography, E was 2.3-fold higher in pelvic procedures (95% confidence interval [CI]: 1.7 to 3.0, p0.001), 1.7-fold higher in upper limb procedures (95% CI: 1.3 to 2.1, p0.001), and 1.4-fold higher in below-the-knee procedures (95% CI: 1.1 to 2.0, p = 0.023). The mean eye dose was 19.1 ± 37.6 μSv. Eye doses were significantly higher in peripheral procedures than in coronary angiography procedures. The mean hand dose was 99.6 ± 196.0 μSv. Hand doses were significantly higher in pelvic than in coronary angiography, upper limb, and below-the-knee procedures.Endovascular procedures for pelvic, upper limb, and below-the-knee disease are accompanied with a higher radiation exposure of the operator than with coronary procedures.

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, respectively. Irrespective of the assay we found a 2.5-4-fold variation of interlaboratory accuracy per assay and lowest MAD values for the DCA assay (0.16 Gy) followed by CBMN (0.34 Gy), gene expression (0.34 Gy) and γ-H2AX (0.45 Gy) foci assay. Binary categories of dose estimates could be discriminated with equal efficiency for all assays, but at doses ≥1.5 Gy a 10% decrease in efficiency was observed for the foci assay, which was still comparable to the CBMN assay. In conclusion, 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.

In Europe, a network for biological dosimetry has been created to strengthen the emergency preparedness and response capabilities in case of a large-scale nuclear accident or radiological emergency. Through the RENEB (Realising the European Network of Biodosimetry) project, 23 experienced laboratories from 16 European countries will establish a sustainable network for rapid, comprehensive and standardised biodosimetry provision that would be urgently required in an emergency situation on European ground. The foundation of the network is formed by five main pillars: (1) the ad hoc operational basis, (2) a basis of future developments, (3) an effective quality-management system, (4) arrangements to guarantee long-term sustainability and (5) awareness of the existence of RENEB. RENEB will thus provide a mechanism for quick, efficient and reliable support within the European radiation emergency management. The scientific basis of RENEB will concurrently contribute to increased safety in the field of radiation protection.

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. © The Author 2010. Published by Oxford University Press. All rights reserved.

Biological dosimetry is an essential tool for estimating radiation dose. The dicentric chromosome assay (DCA) is currently the tool of choice. Because the assay is labor-intensive and time-consuming, strategies are needed to increase throughput for use in radiation mass casualty incidents. One such strategy is to truncate metaphase spread analysis for triage dose estimates by scoring 50 or fewer metaphases, compared to a routine analysis of 500 to 1000 metaphases, and to increase throughput using a large group of scorers in a biodosimetry network. Previously, the National Institutes for Allergies and Infectious Diseases (NIAID) and the Armed Forces Radiobiology Research Institute (AFRRI) sponsored a double-blinded interlaboratory comparison among five established international cytogenetic biodosimetry laboratories to determine the variability in calibration curves and in dose measurements in unknown, irradiated samples. In the present study, we further analyzed the published data from this previous study to investigate how the number of metaphase spreads influences dose prediction accuracy and how this information could be of value in the triage and management of people at risk for the acute radiation syndrome (ARS). Although, as expected, accuracy decreased with lower numbers of metaphase spreads analyzed, predicted doses by the laboratories were in good agreement and were judged to be adequate to guide diagnosis and treatment of ARS. These results demonstrate that for rapid triage, a network of cytogenetic biodosimetry laboratories can accurately assess doses even with a lower number of scored metaphases.

In case of a large-scale radiation accident when hundreds of people may be exposed, it is important to distinguish the severely exposed individuals (or =1 gray), who require early medical treatment, from those less exposed. The aim of our study was to develop a quick population triage method based on automated micronucleus (MN) scoring.Using the MN software module developed by MetaSystems specifically for the Metafer4 platform, about 60 blood samples can be scored in one day. Standard dose response curves were determined for manual and automated MN scoring.The automated MN assay results were closely correlated with MN yields obtained with the manual procedure. A dose of 1 Gy can be estimated with an uncertainty of 0.2 Gy. Corrections for false positives and false negatives by visual inspection of the image gallery did not result in an improved accuracy or reproducibility. To test the automated MN assay in a multicenter setting, an inter-laboratory comparison was performed whereby irradiated blood samples were processed in Ghent University (Belgium) and BfS (Bundesamt fuer Strahlenschutz; Germany). Both laboratories obtained comparable results.These results confirm the efficacy of the automated MN assay for fast population triage in a multicenter setting, in the case of large radiation accidents.

Biological dosimetry, based on the analysis of dicentric chromosomes, is an internationally established, independent method applied in the area of radiation protection. The biodosimetry is mainly performed, in addition to physical dosimetry, with the aim of individual dose assessment, especially after unclear or suspected radiation dose exposures. However, a new biodosimetrical challenge has emerged in recent years in the form of a possible large scale radiation accident potentially involving large numbers of exposed persons. In order to be prepared to act in an efficient manner in such an accident, the established cytogenetic laboratories have increased their cooperation at the national and international level. General experience and results of intercomparisons are reported and future options to increase sample throughput are outlined.

Chromosome translocations in peripheral blood lymphocytes of normal, healthy humans increase with age, but the effects of gender, race, and cigarette smoking on background translocation yields have not been examined systematically. Further, the shape of the relationship between age and translocation frequency (TF) has not been definitively determined. We collected existing data from 16 laboratories in North America, Europe, and Asia on TFs measured in peripheral blood lymphocytes by fluorescence in situ hybridization whole chromosome painting among 1933 individuals. In Poisson regression models, age, ranging from newborns (cord blood) to 85 years, was strongly associated with TF and this relationship showed significant upward curvature at older ages versus a linear relationship (p < 0.001). Ever smokers had significantly higher TFs than non-smokers (rate ratio (RR) = 1.19, 95% confidence interval (CI), 1.09-1.30) and smoking modified the effect of age on TFs with a steeper age-related increase among ever smokers compared to non-smokers (p < 0.001). TFs did not differ by gender. Interpreting an independent effect of race was difficult owing to laboratory variation. Our study is three times larger than any pooled effort to date, confirming a suspected curvilinear relationship of TF with age. The significant effect of cigarette smoking has not been observed with previous pooled studies of TF in humans. Our data provide stable estimates of background TF by age, gender, race, and smoking status and suggest an acceleration of chromosome damage above age 60 and among those with a history of smoking cigarettes. © 2008 Elsevier B.V. All rights reserved.

This interlaboratory comparison validates the dicentric chromosome assay for assessing radiation dose in mass casualty accidents and identifies the advantages and limitations of an international biodosimetry network. The assay's validity and accuracy were determined among five laboratories following the International Organization for Standardization guidelines. Blood samples irradiated at the Armed Forces Radiobiology Research Institute were shipped to all laboratories, which constructed individual radiation calibration curves and assessed the dose to dose-blinded samples. Each laboratory constructed a dose-effect calibration curve for the yield of dicentrics for (60)Co gamma rays in the 0 to 5-Gy range, using the maximum likelihood linear-quadratic model, Y = c + alphaD + betaD(2). For all laboratories, the estimated coefficients of the fitted curves were within the 99.7% confidence intervals (CIs), but the observed dicentric yields differed. When each laboratory assessed radiation doses to four dose-blinded blood samples by comparing the observed dicentric yield with the laboratory's own calibration curve, the estimates were accurate in all laboratories at all doses. For all laboratories, actual doses were within the 99.75% CI for the assessed dose. Across the dose range, the error in the estimated doses, compared to the physical doses, ranged from 15% underestimation to 15% overestimation.

To determine whether computed tomography (CT) could enhance the chromosome aberration yields in paediatric patients.Blood samples were taken before and after CT scans from 10 children for whom the medical justifications for CT examinations were accidental injuries and not diseases as investigated in earlier studies. Chromosome analysis was carried out in lymphocytes by fluorescence plus Giemsa (FPG) staining exclusively in metaphases of the first cell cycle in vitro.The mean blood dose of the 10 children was about 12.9 mGy which was determined by a newly developed dose estimation. Based on more than 20,000 analyzed cells it was found that after CT examination the frequencies of dicentrics (dic) and excess acentric fragments (ace) in lymphocytes were significantly increased. By subdividing the children into two age groups, those with an age from 0.4 years to 9 years and from 10 - 15 years, it became obvious that the observed increase in chromosome aberrations was mainly contributed by the younger age group. In this group the frequency of dicentrics was significantly increased whereas in the older group the observed increase was not significant.Our results demonstrate that CT examinations enhance the dicentrics yields in peripheral lymphocytes of children aged up to 15 years. Since in particular significantly increased dicentric yields could be observed in children with an age from 0.4 - 9 years, it can be assumed that children younger than 10 years may be more radiation sensitive than older subjects.

Purpose: To record the latest information on control levels of translocations in cultured human lymphocytes. Materials and methods: Control-level data from seven European laboratories that are using fluorescence in situ hybridization (FISH) techniques for retrospective biological dosimetry have been combined in a meta-analysis. After correction for the differing probe combinations used, tests of consistency are performed. The combined data have been used to test for individual variation, systematic variation with age, gender and smoking habits. Results: There is a strong variation of translocation yield with age but no variation was detectable with gender or smoking habits. After correction for age, homogeneity tests showed that about 10% of individuals were outside the 95% confidence limits as opposed to 5% expected. From a total of 385, there is an excess of about 20 individuals most of whom have an unexpectedly high yield of translocations. Conclusions: For retrospective biological dosimetry purposes a generic age-dependent control level can be assumed. No other lifestyle factors such as smoking appear to have a significant effect on translocation yield. © 2005 Taylor & Francis Group Ltd.