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In the Mayak Worker Dosimetry System-2013, lung dose is calculated as an average of the three absorbed doses to the bronchial, the bronchiolar and the alveolar regions. Previous epidemiological studies involving Mayak Workers have used a lung dose calculated as the total energy deposited in the lungs divided by the mass. These two definitions lead to very different estimates of lung dose, especially for radon dosimetry. This paper uses the results of recent epidemiological studies to justify the use of a regionally weighted lung dose (wi = 1/3, I = 1, 3) over the use of an 'average lung' dose. [ABSTRACT FROM AUTHOR]

The TECHREC project, funded by the European Commission, will provide Technical Recommendations for Monitoring Individuals for Occupational Intakes of Radionuclides. It is expected that the document will be published by the European Commission as a report in its Radiation Protection Series during 2016. The project is coordinated by the European Radiation Dosimetry Group (EURADOS) and is being carried out by members of EURADOS Working Group 7 (Internal Dosimetry). This paper describes the aims and purpose of the Technical Recommendations, and explains how the project is organised. [ABSTRACT FROM AUTHOR]

Dose assessment after intakes of radionuclides requires application of biokinetic and dosimetric models and assumptions about factors influencing the final result. In 2006, a document giving guidance for such assessment was published, commonly referred to as the IDEAS Guidelines. Following its publication, a working group within the European networks CONRAD and EURADOS was established to improve and update the IDEAS Guidelines. This work resulted in Version 2 of the IDEAS Guidelines, which was published in 2013 in the form of a EURADOS report. The general structure of the original document was maintained; however, new procedures were included, e.g. the direct dose assessment method for 3H or special procedure for wound cases applying the NCRP wound model. In addition, information was updated and expanded, e.g. data on dietary excretion of U, Th, Ra and Po for urine and faeces or typical and achievable values for detection limits for different bioassay measurement techniques. [ABSTRACT FROM AUTHOR]

The International Commission on Radiological Protection (ICRP) Publication 66 Human Respiratory Tract Model (HRTM) treats clearance of materials from the respiratory tract as a competitive process between absorption into blood and particle transport to the alimentary tract and lymphatics. The ICRP recommended default absorption rates for lead and polonium (Type M) in ICRP Publication 71 but stated that the values were not appropriate for short-lived radon progeny. This paper reviews and evaluates published data from volunteer and laboratory animal experiments to estimate the HRTM absorption parameter values for short-lived radon progeny. Animal studies showed that lead ions have two phases of absorption: ∼10 % absorbed with a half-time of ∼15 min, the rest with a half-time of ∼10 h. The studies also indicated that some of the lead ions were bound to respiratory tract components. Bound fractions, fb, for lead were estimated from volunteer and animal studies and ranged from 0.2 to 0.8. Based on the evaluations of published data, the following HRTM absorption parameter values were derived for lead as a decay product of radon: fr = 0.1, sr = 100 d−1, ss = 1.7 d−1, fb = 0.5 and sb = 1.7 d−1. Effective doses calculated assuming these absorption parameter values instead of a single absorption half-time of 10 h with no binding (as has generally been assumed) are only a few per cent higher. However, as there is some conflicting evidence on the absorption kinetics for radon progeny, dose calculations have been carried out for different sets of absorption parameter values derived from different studies. The results of these calculations are discussed. [ABSTRACT FROM PUBLISHER]

The European Commission project IDEAS has produced guidelines for internal dose assessments from monitoring data. A key stage in the guidelines requires assessment of the goodness-of-fit of biokinetic models to bioassay data. The present note extends the use of an autocorrelation coefficient to assess the fits of multiple types of bioassay quantity simultaneously. [ABSTRACT FROM AUTHOR]

Epidemiological studies on uranium miners are being carried out to quantify the risk of cancer based on organ dose calculations. Mathematical models have been applied to calculate the annual absorbed doses to regions of the lung, red bone marrow, liver, kidney and stomach for each individual miner arising from exposure to radon gas, radon progeny and long-lived radionuclides (LLR) present in the uranium ore dust and to external gamma radiation. The methodology and dosimetric models used to calculate these organ doses are described and the resulting doses for unit exposure to each source (radon gas, radon progeny and LLR) are presented. The results of dosimetric calculations for a typical German miner are also given. For this miner, the absorbed dose to the central regions of the lung is dominated by the dose arising from exposure to radon progeny, whereas the absorbed dose to the red bone marrow is dominated by the external gamma dose. The uncertainties in the absorbed dose to regions of the lung arising from unit exposure to radon progeny are also discussed. These dose estimates are being used in epidemiological studies of cancer in uranium miners. [ABSTRACT FROM PUBLISHER]

New information on particle retention of inhaled insoluble material indicates that the ICRP Human Respiratory Tract Model (HRTM) significantly underestimates long-term retention in the lungs. In a previous paper, the information from three studies was reviewed, and a model developed to predict particle retention in the lungs of coal miners was adapted in order to obtain parameter values for general use to predict particle retention in the alveolar–interstitial (AI) region. The model is physiologically based and simpler than the HRTM, requiring two instead of three compartments to model the AI region. The main difference from the HRTM AI model is that a significant fraction, about 35 %, of the AI deposit of insoluble material remains sequestered in the interstitium. The new model is here applied to the analysis of two well-known contamination cases with several years of follow-up data. [ABSTRACT FROM PUBLISHER]

A training course named ‘European Radiation Dosimetry Group/International Atomic Energy Agency Advanced Training Course on Internal Dose Assessment’ was held in Czech Technical University in Prague from 2 to 6 February 2009. The course, jointly organised by the two organisations, had the aim of providing guidance on the application of IDEAS guidelines and of disseminating the results of EC CONRAD Project in relation to internal dosimetry (Work Package 5). At the end of the course a dose assessment exercise was proposed to participants. Four artificial cases, named exercises left to participants, were used to check the capabilities of application of the IDEAS guidelines, gained by participants during the event. The participants had to use both hand calculations and dedicated software, in limited time (7 h). Forty per cent of participants had solved all four cases in the allotted time. The results of the dose assessment were analysed to gain experience in types of errors assessors may make during the evaluations. The result of this intercomparison exercise was promising: half of the results in each case were equal to the ‘reference evaluation estimate’, which was obtained by applying the guidelines correctly. [ABSTRACT FROM PUBLISHER]

EURADOS working group on ‘Internal Dosimetry (WG7)’ represents a frame to develop activities in the field of internal exposures as coordinated actions on quality assurance (QA), research and training. The main tasks to carry out are the update of the IDEAS Guidelines as a reference document for the internal dosimetry community, the implementation and QA of new ICRP biokinetic models, the assessment of uncertainties related to internal dosimetry models and their application, the development of physiology-based models for biokinetics of radionuclides, stable isotope studies, biokinetic modelling of diethylene triamine pentaacetic acid decorporation therapy and Monte-Carlo applications to in vivo assessment of intakes. The working group is entirely supported by EURADOS; links are established with institutions such as IAEA, US Transuranium and Uranium Registries (USA) and CEA (France) for joint collaboration actions. [ABSTRACT FROM PUBLISHER]

The work of Task Group 5.1 (uncertainty studies and revision of IDEAS guidelines) and Task Group 5.5 (update of IDEAS databases) of the CONRAD project is described. Scattering factor (SF) values (i.e. measurement uncertainties) have been calculated for different radionuclides and types of monitoring data using real data contained in the IDEAS Internal Contamination Database. Based upon this work and other published values, default SF values are suggested. Uncertainty studies have been carried out using both a Bayesian approach as well as a frequentist (classical) approach. The IDEAS guidelines have been revised in areas relating to the evaluation of an effective AMAD, guidance is given on evaluating wound cases with the NCRP wound model and suggestions made on the number and type of measurements required for dose assessment. [ABSTRACT FROM AUTHOR]

The CONRAD Project is a Coordinated Network for Radiation Dosimetry funded by the European Commission 6th Framework Programme. The activities developed within CONRAD Work Package 5 ('Coordination of Research on Internal Dosimetry') have contributed to improve the harmonisation and reliability in the assessment of internal doses. The tasks carried out included a study of uncertainties and the refinement of the IDEAS Guidelines associated with the evaluation of doses after intakes of radionuclides. The implementation and quality assurance of new biokinetic models for dose assessment and the first attempt to develop a generic dosimetric model for DTPA therapy are important WP5 achievements. Applications of voxel phantoms and Monte Carlo simulations for the assessment of intakes from in vivo measurements were also considered. A Nuclear Emergency Monitoring Network (EUREMON) has been established for the interpretation of monitoring data after accidental or deliberate releases of radionuclides. Finally, WP5 group has worked on the update of the existing IDEAS bibliographic, internal contamination and case evaluation databases. A summary of CONRAD WP5 objectives and results is presented here. [ABSTRACT FROM AUTHOR]

The European project Alpha-Risk aims to quantify the cancer and non-cancer risks associated with multiple chronic radiation exposures by epidemiological studies, organ dose calculation and risk assessment. In the framework of this project, mathematical models have been applied to the organ dosimetry of uranium miners who are internally exposed to radon and its progeny as well as to long-lived radionuclides present in the uranium ore. This paper describes the methodology and the dosimetric models used to calculate the absorbed doses to specific organs arising from exposure to radon and its progeny in the uranium mines. The results of dose calculations are also presented. [ABSTRACT FROM AUTHOR]

A common problem in internal dosimetry occurs in routine monitoring, when it is required to estimate an intake from a measurement made at the end of a monitoring interval, and the time of intake is unknown. ICRP suggests that it should be assumed that the intake occurred in the middle of the monitoring period. However, it has been shown that this will, in the long-term, lead to biased estimates of a worker's intake and dose. In order to overcome this biasing, the United States Department of Energy (USDOE) recommends a different method based on calculating the intakes for all possible intake times in the interval and then taking an arithmetic average. In a recent paper, it has been shown that both the ICRP and USDOE methods were biased and that the only unbiased estimator of the true intake was obtained by assuming a constant chronic intake throughout the monitoring interval. In all of the analyses carried out to date on this 'Constant Chronic' method, it was assumed that the measurements were exact. In this paper, the effects of assuming either normally or log-normally distributed measurement errors are explored, and the effect on the bias of the intake estimate is investigated. [ABSTRACT FROM AUTHOR]

The IDEAS Guidelines for the assessment of internal doses from monitoring data suggest default measurement uncertainties (i.e. scattering factors, SFs) to be used for different types of monitoring data. However, these default values were mainly based upon expert judgement. In this paper, SF values have been calculated for different radionuclides and types of monitoring data using real data contained in the IDEAS Internal Contamination Database. Results are presented. [ABSTRACT FROM AUTHOR]

In an emergency involving the deliberate or accidental release of radioactive materials, there could potentially be a large number of people who require monitoring for internal contamination. Doses from these measurements will need to be calculated as quickly as possible. Emergency Response Internal Dose Assessment Software (ERIDAS) has been designed for this purpose. [ABSTRACT FROM AUTHOR]

Project IDEAS has produced guidelines for internal dose assessment. An integral part of this process is assessing the goodness of fit of biokinetic models to bioassay data. It is recommended that a fit should only be accepted if (a) it is close enough to the data not to be rejected by a χ² test and (b) if it looks acceptable to 'the eye'. The latter criterion was added to enable the assessor to reject fits which seemed to display some sort of systematic bias. However, there are problems with both of these tests: (a) the χ² test is dependent on the assumed uncertainties which are often unknown, (b) 'by eye' assessment is subjective. In this paper, another statistic, the autocorrelation coefficient of the residuals, ρ, is investigated. The main advantages of the ρ statistic are that it is objective, very sensitive to biasing and independent of the assumed errors. [ABSTRACT FROM AUTHOR]

The EUropean RAdiation DOSimetry Group (EURADOS) initiated in 2005 the CONRAD Project, a Coordinated Network for Radiation Dosimetry funded by the European Commission (EC), within the 6th Framework Programme (FP). The main purpose of CONRAD is to generate a European Network in the field of Radiation Dosimetry and to promote both research activities and dissemination of knowledge. The objective of CONRAD Work Package 5 (WP5) is the coordination of research on assessment and evaluation of internal exposures. Nineteen institutes from 14 countries participate in this action. Some of the activities to be developed are continuations of former European projects supported by the EC in the 5th FP (OMINEX and IDEAS). Other tasks are linked with ICRP activities, and there are new actions never considered before. A collaboration is established with CONRAD Work Package 4, dealing with Computational Dosimetry, to organise an intercomparison on Monte Carlo modelling for in vivo measurements of 241Am deposited in a knee phantom. Preliminary results associated with CONRAD WP5 tasks are presented here. [ABSTRACT FROM AUTHOR]

Intakes and doses are assessed for seven workers who accidentally inhaled particles containing 60Co in the same incident. Comprehensive whole body data to 15 y, and some early urine and fecal data, are available for each individual. The biokinetic and dosimetric models currently recommended by ICRP have been used to assess these cases. It was not possible to obtain good fits to the data using the ICRP models with their default parameter values. However, good fits to all the measurement data were obtained by varying parameter values following a procedure similar to that recommended in recently developed guidelines for assessment of internal doses from monitoring data. It was found that retention in the lungs was much longer than predicted by the ICRP Human Respiratory Tract Model, and so for each case it was necessary to reduce the particle transport clearance of material from the deep lungs. This reduction in lung clearance rates, and the use of specific AMAD values, were the dominating factors in changing assessed doses from those calculated using ICRP default values.

A common problem in internal dosimetry occurs in routine monitoring, when it is required to estimate an intake from a measurement made at the end of a monitoring interval, and the time of intake is unknown. ICRP suggests that, in these cases, it should be assumed that the intake occurred in the middle of the monitoring period. However, it has been shown that this will, in the long term, lead to biased estimates of a worker's intake and dose. In order to overcome this biasing, the United States Department of Energy (USDOE) recommends a different method based on calculating the intakes for all possible intake-times in the interval, and then taking an arithmetic average. In this paper, it is shown that both the ICRP and USDOE methods are biased. An alternative method is suggested, which assumes a constant chronic intake throughout the monitoring interval. Monte Carlo simulations are used to estimate the magnitude of bias for two realistic monitoring programmes using all three methods. It is shown that the proposed method is unbiased and also yields estimates of intake that are generally closer to the actual intake, than the other two. The Monte Carlo conclusions are backed up by a theoretical analysis of bias. Finally, the source of bias in the apparently intuitive approach of the USDOE method is revealed by viewing the problem from a Bayesian perspective. [ABSTRACT FROM AUTHOR]

A correction to the article "Eurados Coordinated Action on Research, Quality Assurance and Training of Internal Dose Assessments," which was published in a 2011 issue is presented.