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A new method has been developed to identify and localize a single hot particle in the lungs using an array of four high-purity germanium detectors. The method is based upon calculating a set of three count rate ratios (generated by each individual detector in the array) that are evaluated in sequence to designate whether the measured deposition can be associated with a hot particle rather than the default assumption of a uniform activity distribution. Identification and localization of the hot particle are determined from a single in vivo measurement in which detectors are positioned above and below the thorax. The method was tested using an anthropomorphic thorax phantom in which point sources of 241Am, 137Cs and 60Co were individually inserted in the lungs at 15 different locations and were measured using a scanning bed whole-body counter. Depending upon source location and photon energy, a bias of −35% up to +76% could be introduced by falsely assuming a uniform activity distribution in the lungs. This bias would directly translate to an erroneous dose estimate to the lungs. It was demonstrated that by using the appropriate detector efficiencies for the single hot particle, the bias associated with the activity determination is reduced to <10% and ~2% in average. [ABSTRACT FROM AUTHOR]

The solubility of 7Be particles was measured in vitro as part of an evaluation of the exposure of workers who inhaled particles released from a damaged source. Initial in vivo measurements performed with one worker revealed that a significant fraction of 7Be particles were rapidly removed from the respiratory tract with a half-life of approximately 0.4 days. Since rapid clearance of 7Be was not supported by conventional biokinetic models, a study of the solubility of the particles in vitro was launched. A representative sample of the 7Be particles was collected from the damaged source and exposed to a surrogate lung fluid solution for increasing periods of time. Over 98% of the material was dissolved at the end of the dissolution period. The effective half-time for solubility of the majority of 7Be particles was found to be ≅ 0.4 days and is wholly consistent with results of in vivo measurements. [ABSTRACT FROM AUTHOR]

Several workers were internally exposed to 7Be particles following their dispersion in air from a damaged electrodeposited source. A series of in vivo measurements performed with one worker up to 108 days post exposure determined that retention of 7Be in the thoracic region of the respiratory tract was best described by a two-component exponential function with halflives of ~0.4 and ~109 days. The initial deposition in the thoracic region was estimated to be 6.8 kBq. The concentration of 7Be in single void urine samples collected from this worker up to 3 days post intake ranged from 1 to 10 Bq/l. In the absence of specific knowledge about the physical and chemical characteristics of the inhaled particles, the committed effective dose was estimated to be 0.3 µSv. [ABSTRACT FROM AUTHOR]

The performance characteristics of a shadow-shield whole-body counter system with an array of four high-resolution germanium detectors using whole-body and organ-specific (lungs, liver, head, knee and thyroid) physical phantoms are described. Detection efficiency and minimum detectable activities for selected radionuclides and several measurement configurations are presented. Results demonstrate that the system meets the requirements for direct radio bioassay and that detection efficiency and minimum detectable activities are similar in magnitude to other whole-body (or organ) counting systems installed in fully shielded structures. [ABSTRACT FROM AUTHOR]

The transfer of 226Ra from irrigation water to basil crops was studied in field conditions. A dedicated basil plot was established and divided into test and control subplots irrigated with water having high (2.1 Bq L-1) and low (0.05 Bq L-1) activity concentrations of 226Ra, respectively. The experiment was performed over a period of 18 months during the autumn, winter and spring seasons, altogether eight cycles of growth and harvest. The activity concentration of 226Ra in basil grown in the test subplots was found to increase from a value of 0.6 Bq kg-1 up to 5.1 Bq kg-1 with successive cycles, compared to a mean value of 0.2 Bq kg-1 for basil grown in the control subplots. The increase in activity concentration of 226Ra in basil grown in the test subplots is mainly attributed to its build-up in the soil in which the level of 226Ra was found to increase by ~ 40%. The effective uptake of 226Ra from the irrigation water (via soil) by the basil plants was found to be approximately 0.4%. The maximal radiation dose following consumption of basil crops grown in the test subplots is negligible (~3 μSv/y)., (© The Author(s) 2021. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

Several workers were internally exposed to 7Be particles following their dispersion in air from a damaged electrodeposited source. A series of in vivo measurements performed with one worker up to 108 days post exposure determined that retention of 7Be in the thoracic region of the respiratory tract was best described by a two-component exponential function with half-lives of ~0.4 and ~109 days. The initial deposition in the thoracic region was estimated to be 6.8 kBq. The concentration of 7Be in single void urine samples collected from this worker up to 3 days post intake ranged from 1 to 10 Bq/l. In the absence of specific knowledge about the physical and chemical characteristics of the inhaled particles, the committed effective dose was estimated to be 0.3 μSv., (© The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

The dependency of radon emanation on soil texture was investigated using the closed chamber method. Ground phosphate rock with a large specific surface area was analyzed, and the presence of inner pores, as well as a high degree of roughness and heterogeneity in the phosphate particles, was found. The average radon emanation of the dry phosphate was 0.145 ± 0.016. The emanation coefficient was highest (0.169 ± 0.019) for the smallest particles (<25 μm), decreasing to a constant value (0.091 ± 0.014) for the larger particles (>210 μm). The reduction rate followed an inverse power law. As expected, a linear dependence between the emanation coefficient and the specific surface area was found, being lower than predicted for the large specific surface area. This was most likely due to an increase in the embedding effect of radon atoms in adjacent grains separated by micropores. Results indicate that knowledge of grain radium distribution is crucial to making accurate emanation predictions., (Copyright © 2017 Elsevier Ltd. All rights reserved.)