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Eurados-ideas guidelines (version 2) for the estimation of committed doses from incorporation monitoring data
Abstract and Figures
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.
Figures - uploaded by C-M Castellani
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... According to the ICRP publication 78 that provides a method for evaluating the internal exposure of workers 2) , it is suggested that a single intake can be estimated by dividing the radioactivity measurement by the radioactivity prediction for a unit intake. Furthermore, in the IDEAS guidelines that describe the evaluation procedures for internal exposures 3) , it is suggested that a single intake can be estimated from multiple measurements in which the uncertainly of measurement is considered. Generally, the intake estimation is obtained by fitting the radioactivity prediction structured with a linear combination of radioactivity prediction for the unit intake and the unknown intake quantity to the radioactivity measurement in the body or excretions. ...
... To employ the least squares method, the number of intakes must be lower than the number of measurements. From the ICRP 2) and IDEAS 3) guidelines, only a single intake was considered, and the estimation of multiple intakes was not sufficiently conducted. Using the intake estimation method with singular-value decomposition in this research, estimation was possible regardless of the dimensional relationship between the number of intakes and the number of measurements. ...
... The likelihood function described in IDEAS Guidelines (57) was used for the interpretation of most of the measurement values ...
... For urine and lung data, we used S values (see eq. 2) of 0.5 and 0.35, respectively, consistent with the recommendation in the IDEAS guidelines (57) . For most post-mortem measurements, an S of 0.1 was used, except for the LN TH measurement for Case 0269 where an S of 0.3 was used following Puncher et al. (3) . ...
The respiratory tract tissues of four former nuclear workers with plutonium intakes were radiochemically analyzed post mortem by the United States Transuranium and Uranium Registries. Plutonium activities in the upper respiratory tract of these individuals were found to be higher than those predicted using the most recent biokinetic models described in publications of the International Commission on Radiological Protection. Modification of the model parameters, including the bound fraction, was not able to explain the data in one of the four individuals who had inhaled insoluble form of plutonium. Literature review points to the presence of—and a significant retention of—plutonium in the scar tissues of the lungs. Accordingly, an alternate model with scar-tissue compartments corresponding to larynx, bronchi, bronchioles, alveolar-interstitium and thoracic lymph nodes was proposed. The rates of transfer to the scar tissue compartments were determined using Markov Chain Monte Carlo analysis of data on urinary excretion, lung counts and post-mortem measurements of liver, skeleton and individual respiratory tract compartments, as available. The posterior models predicted that 20–100%—depending on the solubility of the material inhaled—of the activities retained in the respiratory tract were sequestered in the scar tissues.
... In general, the uncertainties due to both calibration and the variation of background signal could be controlled within 5%. 49 However, it is noted that all calibrations were performed with reference thyroid phantoms, and its uncertainty due to calibration should be further considered for individual monitoring. On the other hand, it was also pointed out that although uncertainties due to the variation of background signal could be relatively easily controlled by shielding or deducting the background, the MDA would significantly increase with the increase of environmental background signal especially in the case of nuclear accidents. ...
... For more accurate assessments of the internal dose, the EURADOS-IDEAS has established a guide. 49 Table 1 lists its general requirements on the typical scattering factors for in vivo measurement of radionuclides emitting photons with energy higher than 100 keV. Based on a previous review, it is still difficult to accomplish all the requirements in the in vivo monitoring of 131 I in the thyroid by using portable gamma spectrometers at present. ...
Iodine-131 is a highly toxic and volatile artificial radionuclide that is easily inhaled or ingested by the human body and selectively accumulates in thyroid tissue. With the development of nuclear medicine and nuclear power plants, the unintended release of ¹³¹I has been widely studied, and the in vivo measurement of ¹³¹I in the thyroid has become a research hotspot in the field of radiation protection. In recent decades, several methods and devices have been developed for in vivo measurements with respect to different measurement purposes and requirements. In this work, for more accurate determinations of individual ¹³¹I activity in the thyroid in the field, the uncertainties of measurements by using portable gamma spectrometers were reviewed and analyzed, and monitoring strategies for improving the accuracy were proposed and prospected.
... In this case, all urine samples were analyzed using radiochemical alpha spectrometry (RAS), and therefore "full count data" (i.e., number of gross and background counts, ratio of background count time to sample count time, normalization coefficient, and its logarithmic standard deviation) were available allowing the use of the "exact likelihood function." The exact likelihood function is more accurate than the normal-lognormal approximation typically used in internal dosimetry applications (Castellani et al. 2013). In addition, the exact likelihood function can be used for negative measurements that are often encountered in bioassays. ...
A glovebox breach at the plutonium facility at Los Alamos National Laboratory potentially exposed 15 individuals to 238Pu aerosols. One of the individuals (P0) received two 1-g intravenous DTPA treatments, one on the day of the intake and another the following day. Several urine samples were collected from the individuals involved in the incident. Particle size analysis on the PPE and solubility analysis of the particles on a filter sample were conducted in vitro. The applicability of the results from the in vitro studies for dose assessment was questionable because of the effect of the cloth mask the workers were wearing for COVID-related protection. Based on several considerations, including the effect of cloth masks on the "effective" particle size inhaled and the analysis of fecal-to-urine ratio, the default Type M 1 μm AMAD model was used to estimate intakes and doses. Using the urinary excretion data collected after 100 d post last chelation treatment, the committed effective dose, E(50), for P0 was calculated to be 5.2 mSv. For all others, the bioassay data were consistent with no intakes or very small intakes [corresponding to E(50) less than 0.1 mSv].
... The Internal Dosimetry Laboratory of the Nuclear Technology Development Center (LDI/CDTN) located in Belo Horizonte -MG, Brazil is contamination of workers of the Research and Production of Radiopharmaceuticals Unit (UPPR/ CDTN) involved in the production of 18 F-FDG. Studies with phantoms have already been performed for the calibration of the internal contamination monitoring system with 18 F-FDG (9)(10)(11)(12), these simulators are used to obtain the calibration coefficient (CC). The CC is one of the most important parameters to calculate the activity present in the sample. ...
A atividade mínima detectável (AMD) representa o valor mínimo de atividade que é detectada em um sistema de monotoração. Existem diversas metodologias que podem ser utilizadas para calcular a AMD, no entanto os resultados para cada uma destas podem ser divergentes. Laboratórios de dosimetria interna in vivo devem dispor deste parâmetro para cada tipo de geometria de contagem, bem como, para cada tipo de radionuclídeo de interesse, visando a otimização do processo de monitoração interna. O objetivo deste trabalho foi comparar três tipos de metodologias de cálculo utilizadas na determinação da AMD com os resultados obtidos experimentalmente. As metodologias de cálculo utilizadas foram as sugeridas por Currie (1968), a publicada em Health Physics Society N13.30 (1996) e a ISO 11929 (2018). A monitoração de um phantom de cabeça contendo na região correspondente ao cérebro 18F-FDG foi realizada para a obtenção da AMD experimental. Os resultados obtidos para os valores de AMDs utilizando as três diferentes metodologias apresentaram diferenças de acordo com as faixas de atividades analisadas. As incertezas do fator de calibração e Background do sistema são os principais parâmetros entre as três metodologias de cálculo que influenciaram nos resultados obtidos.
... It can be useful in detecting and quantifying an inhalation exposure to a relatively insoluble form of radionuclide, because clearance via feces is the predominant excretion mode in such a situation (17). Nevertheless, this method carries significant uncertainty as stated by EURADOS where it described that the transit time through the alimentary tract is subject to large inter/intra subject variations (21). ...
... assumed to be distributed lognormally with a geometric standard deviation (GSD) of 3.0 for measurements before 1949, a GSD of 2.0 for measurements between 1949 and 1957, and a GSD of 1.6 for measurements after 1957 [45]. The less than MDA/2 urine bioassay measurements were replaced by MDA/2 and marked as '<LOD' in IMBA. ...
Purpose
Radiation dose estimates in epidemiology typically rely on intake predictions based on urine bioassay measurements. The purpose of this article is to compare the conventional dosimetric estimates for radiation epidemiology with the estimates based on additional post-mortem tissue radiochemical analysis results.
Methods
The comparison was performed on a unique group of 11 former Manhattan Project nuclear workers, who worked with plutonium in the 1940s, and voluntarily donated their bodies to the United States Transuranium and Uranium Registries.
Results
Post-mortem organ activities were predicted using different sets of urine data and compared to measured activities. Use of urinalysis data collected during the exposure periods overestimated the systemic (liver+skeleton) deposition of ²³⁹ Pu by 155±134%, while the average bias from using post-exposure urinalyses was –4±50%. Committed effective doses estimated using early urine data differed from the best estimate by, on average, 196±193%; inclusion of follow-up urine measurements in analyses decreased the mean bias to 0.6±36.3%. Cumulative absorbed doses for the liver, red marrow, bone surface, and brain were calculated for the actual commitment period.
Conclusion
On average, post-exposure urine bioassay results were in good agreement with post-mortem tissue analyses and were more reliable than results of urine bioassays collected during the exposure.
CADORmed is a free bespoke Excel® tool for committed effective dose assessment using latest dose coefficients from ICRP OIR publications. The field of application of CADORmed is special monitoring, and it is not available for the dose assessment of chronic exposure. Calculations are made according to EURADOS guidelines and principles (EURADOS report 2013-1). The Chi-squared test for the goodness of fit is made with a scattering factor for type A and type B errors according to the EURADOS report. The Intake is calculated with the maximum likelihood method. Measurements that are below the detection limit are incorporated by the use of an allocated value equal to one-half or one-quarter of the detection limit. The Identification of rogue data can easily be achieved. Advanced options may also be used: mixed ingestion and inhalation, mixture of default absorption types, correction for DTPA treatment, calculation with a new intake and adjustment when the date of intake are unknown. The validation of the tool has been included in the work plan of EURADOS WG 7. The validation plan has been defined and the validation tests completed. All changes are traced in a Quality Assurance document.
Accidental inhalation of plutonium at the workplace is a non-negligible risk, even when rigorous safety standards are in place. The intake and retention of plutonium in the human body may be a source of concern. Thus, if there is a suspicion of a significant intake of plutonium, medical countermeasures such as chelation treatment may be administered to the worker. The present work aimed to interpret the bioassay data of a worker involved in an inhalation incident due to a glovebox breach at Los Alamos National Laboratory’s plutonium facility. The worker was treated with intravenous injections of calcium salts of diethylenetriaminepentaacetic acid (DTPA) in an attempt to reduce the amount of plutonium from the body and therefore reduce the internal radiation dose. It is well known in the internal dosimetry field that the administration of chelation treatment poses additional challenges to the dose assessment. Hence, a recently developed chelation model was used for the modeling of the bioassay data. The objectives of this work are to describe the incident, model the chelation-affected and non-affected bioassay data, estimate the plutonium intake, and assess the internal radiation dose.
After nuclear accidents, people can be contaminated internally via ingestion, inhalation and via intact skin or wounds. The assessment of absorbed, committed doses after internal exposure is based on activity measurement by in vivo or in vitro bioassay. Estimation of dose following internal contamination is dependent on understanding the nature and form of the radionuclide. Direct counting methods that directly measure γ-rays coming from within the body or bioassay methods that measure the amount of radioactive materials in urine or feces are used to estimate the intake, which is required for calculating internal exposure doses. The interpretation of these data in terms of intake and the lifetime committed dose requires knowledge or making assumptions about a number of parameters (time, type of exposure, route of the exposure, physical, biological and chemical characteristics) and their biokinetics inside the body. Radioactive materials incorporated into the body emit radiation within the body. Accumulation in some specific organs may occur depending on the types of radioactive materials. Decorporation therapy is that acceleration of the natural rate of elimination of the contaminant will reduce the amount of radioactivity retained in the body. This article presents an overview of treatment of radiological contamination after internal contamination.
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.
The PLUTO software package was developed at Sellafield to make optimum use of the analysis data from plutonium in urine samples in arriving at the best estimate of intake/uptake. The program prompts the assessment parameters required to fit the data to the excretion function using the maximum likelihood method. A critical appraisal is given of the relative strengths and weaknesses of this assessment package.
The high concentration of uranium and thorium in certain Brazilian areas provides an opportunity to evaluate the radiation exposure due to intake of radionuclides by the populations that live and work in areas with a high natural radiation background. Buena, where this study was conducted, is a small village on the coast in the northern part of Rio de Janeiro State, characterised by the presence of a large deposit of monazite sand. In this paper. the concentrations of U-238, U-234, Th-232, Th-228, Ra-228, Ra-226 and Pb-210 in faecal samples from inhabitants of this area were determined by a sequential analytical method. The results of the average concentrations in faeces of inhabitants of Buena are 9.4 +/- 3.4 mBq g(ash)(-1), for U-238, 9.2 +/- 4.0 mBq g(ash)(-1) for U-234, 7.0 +/- 4.2 mBq g(ash)(-1) for Th-232 256.1 +/- 134.6 mBq g(ash)(-1) for Th-228, 335.5 +/- 192.8 mBq g(ash)(-1) for Ra-228, 156.6 +/- 74.1 mBq g(ash)(-1) for Ra-226 and 66.7 +/- 17.7 mBq g(ash)(-1) for Pb-210. The results were compared with background concentrations from faecal Janeiro City. For most of the radionuclides analysed, the average concentration in samples from individuals living in Rio de faeces from inhabitants of the high natural radiation background was higher than the concentration found in Rio de Janeiro, considered a 'normal' background area.
210Po concentrations in urine samples from individuals exposed in different areas of a uranium milling and mining complex in Brazil were measured, in search of possible indications of internal contamination by Rn and daughters. Results were compared with 210Po excretion by a control group from Rio de Janeiro. The influence of smoking habits on 210Po excretion was also tested for the two groups. The results have shown a statistically significant increase of 210Po in the smokers' urinary excretion for the control group relative to non-smokers. In the workers group, the difference was not significant. Occupationally exposed personnel at some areas of the plant had statistically significant higher excretions of 210Po in urine than the control group.
Thorium is a natural radioactive element and has numerous applications. The extremely low annual limits on intake of national and international regulations and the extreme difficulties in detecting thorium in the body or excreta makes high demands on the techniques used for the monitoring of exposed workers. In addition, there are problems resulting from a lack of information on the biokinetics of thorium and its radioactive decay products. A programme for monitoring thorium intakes on the basis of new regulations in Germany, is described.
The aim of the study was to make a realistic estimation of 241Am activity in the body of the people with old internal contamination. A whole-body counter equipped with HPGe and LEGe detectors was used as a major tool. Calibration was performed using phantoms of the human head, knee, arm and leg of different origin. Using it for the evaluation of 241Am in the body of an internally contaminated case, body activity was estimated to be 5.6 kBq and its uncertainty was in the range given by factor 1.5 ± 1.
The normal dietary and fluid intake and urinary and fecal excretion of 234 U and ${}^{238}{\rm U}$ were determined in humans under strictly controlled conditions in the Metabolic Research Ward at Hines Hospital. These values formed the basis of the metabolic balances of these uranium isotopes. The major pathway of 234 U and of ${}^{238}{\rm U}$ excretion was via the intestine while the urinary 234 U and ${}^{238}{\rm U}$ were very low, averaging 2% of the total excretion. The uranium balances were roughly in equilibrium. These data were used in combination with measurements of tissue concentrations of uranium from nonoccupationally exposed humans to calculate steady-state uptake factors for environmental exposure to uranium isotopes during baseline conditions of a normal dietary intake.