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Abstract

Decentralized wastewater systems treat, dispose and reuse the wastewater in the vicinity of source, reducing the sewage transportation cost to minimal. As an alternative to centralized systems it can function as a satellite system or an individual wastewater treatment unit. Design an onsite facility applies the same sizing procedure compared the conventional large scale systems, whereas the input flow data and its variability, the model parameters could differ. In this study a small size treatment unit was designed by biokinetic modeling, where the model parameters were estimated using analytical methods. As a result of the calculation the biomass build-up and the quality of the treated effluent was predicted and the operation parameters were determined in summer and winter operation.

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Abstract  

In most cases the measurement of radioactivity in an environmental or biological sample will be followed by some estimation of dose and possibly risk, either to a population or an individual. This will normally involve the use of a dose coefficient (dose per unit intake value) taken from a compendium. In recent years the calculation of dose coefficients has seen many developments in both biokinetic modelling and computational capabilities. ICRP has recommended new models for the respiratory tract and for the systemic behavior of many of the more important elements. As well as this, a general age-dependent calculation method has been developed which involves an effectively continuous variation of both biokinetic and dosimetric parameters, facilitating more realistic estimation of doses to young people. These new developments were used in work for recent ICRP, IAEA and CEC compendia of dose coefficients for both members of the public (including children) and workers. This paper presents a general overview of the method of calculation of internal doses with particular reference to the actinides. Some of the implications for dose coefficients of the new models are discussed. For example it is shown that compared with data in ICRP Publications 30 and 54: the new respiratory tract model generally predicts lower deposition in systemic tissues per unit intake; the new biokinetic models for actinides allow for burial of material deposited on bone surfaces; age-dependent models generally feature faster turnover of material in young people. All of these factors can lead to substantially different estimates of dose and examples of the new dose coefficients are given to illustrate these differences. During the development of the new models for actinides, human bioassay data were used to validate the model. Thus, one would expect the new models to give reasonable predictions of bioassay quantities. Some examples of the bioassay applications, e.g., excretion data for the plutonium model, are discussed briefly.

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Abstract  

In vivo skull measurements of 210Pb have been performed to assess the individual, chronic exposures of two persons living for 28 years in a house with a distinctly enhanced radon concentration of more than 10,000 Bq/m3. A partial body counter consisting of 4 HPGe detectors, which were placed close to parietal positions of the head, was used in the study. The lower limit of detection of 210Pb activity in the skeleton was found to be 40 Bq. Lead-210 activities of up to 152 Bq were found in the test persons, whereas no activity could be measured in an unexposed control person. The cumulative uptake of 210Pb into the body was assessed for each single test person by using the ICRP respiratory tract and the biokinetic models. A fairly good agreement (within a factor of 2) between in vivo measurements and model was achieved for these two test persons. The technique used in the study may be a useful tool to evaluate assumptions, which have to be made for the reconstruction of individual, cumulative exposures to high radon concentrations.

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Abstract  

Changes and refinements to original biokinetic models, based on postmortem radiochemical measurements of the concentration and distribution of actinides in tissues obtained from volunteer donors with known occupational experience with actinides, are discussed with emphasis on applications to operational health physics. Analysis of five whole body donations to the United States Transuranium Registry indicates that the239Pu model put forth in ICRP Publication 30 is generally applicable, although there is a significant fraction missing from the model that is retained in the muscle. For241Am, the more recent model put forth in ICRP Publication 48 fits the autopsy data better than the model in Publication 30, although the observed retention half-time in the liver is on the order of two to three years rather than 20 years proposed by the model. An estimated 20% of the initial systemic deposition for241Am goes to the muscle, where it has a residence half-time estimated at ten years. For both Pu and Am, less than 5% of the skeletal actinide in the skeleton is found in the marrow. The highest concentrations appear to be associated with the periosteum and endosteum. A significantly greater fraction of inhaled Pu and Am is retained in the lungs than is predicted by current models. Differences in the actinide distribution between lung and the associated lymph nodes are observed in smokers as compared with non-smokers.

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Abstract  

The main objective of this paper is to point out problems associated with interpretation of bioassay monitoring in view of the existing biokinetic models. The exposure to thorium in Brazil is given in this paper as an example of the seriousness of the problem.

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Abstract  

For more than 25 years, the United States Transuranium and Uranium Registries (USTUR) and the Dosimetry Registry of the Mayak Industrial Association (DRMIA) of the Russian Federation have, each independently, collected tissues at autopsy from workers with potential or confirmed body burdens of actinide elements resulting from occupational exposures. Tissues, thus obtained, were radiochemically analyzed for actinides for the purpose of evaluating the biokinetics of these elements in the human body. Scientists of these two organizations have recently begun a collaborative research program to compare, combine and analyze the data to verify or refine biokinetic models needed for radiation dosimetry.

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Journal of Radioanalytical and Nuclear Chemistry
Authors: S. Ridone, D. Arginelli, E. Inglese, A. Lucca, R. Matheoud, A. Miranti, M. Montalto, C. Peroni, M. Rudoni, C. Secco, S. Vallegiani, and L. Vigna

Abstract  

The radiopharmaceutical [153Sm]Sm-EDTMP is administered for painful bone metastases with the standard dosage of 37 MBq/kg, without evaluation of patient individual characteristics. For a better dose estimate in vivo stability should be considered, because labelled and unlabelled samarium do not have the same metabolic pathway. We evaluated radiopharmaceutical in vitro stability, measuring the activity by beta and gamma spectrometry. Subsequently we verified in vivo stability on serial blood and urine samples. The percentage of the unlabelled radiopharmaceutical is high and, on the basis of radiochemical data as well as blood clearance and urine excretion, we calculated the main parameters for a preliminary biokinetic model.

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Abstract  

Measurements of239+240Pu in human tissues, from nuclear weapons testing, provide an invaluable source of data for verifying the uptake and distribution of radionuclides in the body. Measured concentrations of239+240Pu in lung, tracheobronchial lymph nodes, liver and skeleton have been compared with concentrations calculated using estimated plutonium intakes, the ICRP Publication 66 Respiratory Tract Model and the ICRP Publication 67 biokinetic model for plutonium. Measurement data tend to fall between the concentrations estimated on the basis of Type M and Type S absorption parameters. This indicates that the models represent the movement of plutonium through the body reasonably well.

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Abstract  

This paper describes the merits and demerits of each technique utilized for determining the intakes of radioactive materials in workers with particular emphasis on the intake of thorium, uranium, and plutonium. Air monitoring at work places have certain flaws, which may give erroneous estimates of intake of the radionuclides. Bioassay techniques involve radiochemical determinations of radionuclides in biological samples such as urine, feces etc, and employing biokinetic models to estimate the intake from such measurements. Though, highly sensitive and accurate procedures are available for the determination of these radionuclides biokinetic models employed produce large errors in the estimate. In vivo measurements have fundamental problems of poor sensitivities. Also, due to non-availability of such facilities at most of the nuclear sites transporting workers at different facilities may cost a lot of financial resources. It seems difficult to defend in the court of law that determination of intake of radioactive material in workers by an individual procedure is accurate; at the best these techniques may be employed to obtain only an estimate of intake.

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Summary  

The 238U and 232 Th concentrations were measured in various potable water samples collected from various cities in Morocco using CR-39 and LR-115 type II solid state nuclear track detectors (SSNTDs). The measured 238U and 232 Th concentrations ranged from 0.37±0.02 to 13.60±0.97 mBq . l-1 and 0.33±0.02 to 7.10±0.49 mBq . l-1, respectively. Alpha-activities due to annual 238U and 232 Th intakes were assessed in various compartments of the human body of adult members of the Moroccan population using ICRP biokinetic models. The equivalent doses due to annual intakes of 238U and 232 Th were evaluated. The influence of the target tissue mass and the activities of 238U and 232 Th on the annual committed equivalent doses in the compartments of the human body was investigated.

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