Uncertainties in doses calculated according to ICRP recommendations after inhalation of 239PUO2 and early chest monitoring

This study estimates uncertainties in Pu biokinetics and effective doses calculated after an acute inhalation exposure to (239)PuO(2) according to ICRP recommendations (default values for aerosols size and PuO(2) dissolution parameters). This was performed using the most recently reported variations in model parameters and simulations after a Monte Carlo approach. Without chest monitoring, uncertainties in thoracic retention and plutonium excretion was 8-10 (95% confidence interval as the ratio between 97.5 and 2.5 percentiles of the lognormal distributions) up to 900 d after exposure. Early chest monitoring reduces significantly the uncertainties in plutonium biokinetics and doses which remain within a 95% confidence interval of 2.3 as compared with 6.6, without monitoring. Analysis of bioassay data previously reported shows that the dose delivered to some individuals can be out of the confidence interval, which was mostly due to an inhibition of the late mechanical clearance of the alveolar interstitium.     

A computational study of the urinary excretion rates for 339Pu using new ICRP internal dosimetry models

A computational study of the urinary excretion rates for 239Pu has been carried out using a methodology which involved the solution of a complete compartmental model describing the biokinetic behaviour of inhaled plutonium aerosols in the human body. The methodology, after proper validation, was applied to investigate the dependence of urinary excretion rates for 239Pu on the transfer rates given in the complete compartmental model. For this purpose, the default values of the transfer/absorption rates were modified by factors of 2 and 4 and urinary excretion rates were computed on 1, 10, 100, 1000 and 10,000 d post-intake. The percentage variations in the urinary excretion rates as a result of the modified transfer rates were computed for exposures to Type M and S aerosols of 239Pu. These results facilitated the identification of parameters significantly affecting the short-term and long-term urinary excretion rates. In addition, time variations of the predicted ratios of 239Pu activity in daily urine to that in blood (excretion ratios) were studied for the three biokinetic models of plutonium: the ICRP 67 model, the modified ICRP 67 model with the compartment STI to urinary bladder removed and Luciani and Polig's model. All the computational results are presented and discussed in this paper.     

Prediction of monitoring data for 239Pu accidentally injected via wound site based on the proposed NCRP wound model

In response to the consultation from the National Council on Radiation Protection and Measurements (NCRP) to the International Commission on Radiological Protection (ICRP) committee 2, retention and excretion of 239Pu deposited at wound site were calculated by coupling together the proposed NCRP wound model and the current ICRP systemic model of Pu. The physicochemical forms considered were the soluble form categorized into 'Strong Retention', and the colloidal, particulate and fragmentary forms. The results are summarized as follows. If in soluble form, immediate medical intervention is needed to prevent uptake of radionuclides to body tissues, and prompt wound monitoring is essential for an accurate estimation of the initially deposited radioactivity. If in particulate form, a multi-component exponential equation leads to an overestimation of the absorption rate to blood because of significant lymph node drainage. The committed doses in the organs for direct transfer of 239Pu to the blood may be applied to every cases of accidental injection except for fragments.     

Joint determination of 238Pu, 239, 240Pu, 241Pu, and 90Sr in soil

A procedure for determination of ²³⁸Pu, ^{239, 240}Pu, ²⁴¹Pu, and ⁹⁰Sr in soil is reported. ²⁴¹Pu was determined by liquid scintillation counting in the same Pu sample that was obtained from the initial soil sample by coprecipitation with neodymium fluoride and used for α-spectrometric measurements. ⁹⁰Sr was determined by the carbonate method after ion-exchange separation of plutonium. The ⁹⁰Sr activity in the sample was estimated using two measurements of the Cherenkov radiation of ⁹⁰Y, the first made just after separation of ⁹⁰Sr from ⁹⁰Y. This technique allows monitoring of ⁹⁰Y accumulation, excluding contributions from foreign radionuclides. Original Russian Text & V.N. Zabrodskii, Yu.I. Bondar’, A.S. Komarovskaya, V.N. Kalinin, 2006, published in Radiokhimiya, 2006, Vol. 48, No. 1, pp. 87–91.     

Comparisons of the thoracic trauma index with other models

The thoracic trauma index (TTI) provides an indication of the severity of injuries received by motor vehicle occupants in side-impact collision environments. The index was derived from results on two sets of cadaver tests. Using a variety of statistical and numerical methods, the authors reanalyzed the data from these 80+ cadaver tests to construct a better measure of injury than TTI. Indices generated by these analyses were compared with TTI using the following quantitative measures: monotonicity, overlap, percentage correct, and sensitivity. The values of these measures are broadly similar for all indices and none of the new indices consistently performs better than TTI. This suggests that TTI is as good a predictor of injury as any of the several alternative models created.     

Standard Reference Data on the Nuclear Characteristics of the Alpha-Radiating Radionuclides 226Ra, 233U, 238Pu,and 239Pu

Estimated values of the half-life, the energy and absolute emission probability of alpha-particles for radionuclides, forming part of the standard spectrometric alpha-radiation sources: ²²⁶Ra with daughter decay products ²³³U, ²³⁸Pu, and ²³⁹Pu, are presented as a draft of standard reference data. The recommended values are obtained by analyzing and selecting published estimated and experimental data (up to December 2000).     

Effect of uncertainty in transfer rates for the ICPR publication 67 biokinetic model on dose estimation for 239Pu from results of individual monitoring. International Commission on Radiological Protection

The radiation dose due to internal exposures from 239Pu is mainly estimated by measuring actual urinary or faecal excretion of activity and comparing those values with the standard excretion rates calculated from the models of the International Commission on Radiological Protection (ICRP). Recently, on the other hand, uncertainties in the ICRP's models and parameters are under consideration because of the paucity of human data. In addition, there is a possibility of variation between individuals. A code has been developed to reproduce the ICRP's dose coefficients and excretion rates for 239Pu, which is one of the most important elements for occupational exposure. By using this code, the respective transfer rates for the ICRP Publication 67 biokinetic model were modified, and the effect owing to these changes on present hazard assessment was investigated. As a result, it was shown that dose estimates for workers exposed to 239Pu were not very sensitive to changes in these transfer rates.     

Automatic application of ICRP biokinetic models in voxel phantoms for in vivo counting and internal dose assessment

As part of the improvement of calibration techniques of in vivo counting, the Laboratory of Internal Dose Assessment of the Institute of Radiological Protection and Nuclear Safety has developed a computer tool, 'OEDIPE', to model internal contamination, to simulate in vivo counting and to calculate internal dose. The first version of this software could model sources located in a single organ. As the distribution of the contamination evolves from the time of intake according to the biokinetics of the radionuclide, a new facility has been added to the software first to allow complex heterogeneous source modelling and then to automatically integrate the distribution of the contamination in the different tissues estimated by biokinetic calculation at any time since the intake. These new developments give the opportunity to study the influence of the biokinetics on the in vivo counting, leading to a better assessment of the calibration factors and the corresponding uncertainties.     

Estimation of skin impedance models with experimental data and a proposed model for human skin impedance

The skin is a complex biological tissue whose impedance varies with frequency. The properties and structure of skin changes with the location on the body, age, geographical location and other factors. Considering these factors, skin impedance analysis is a sophisticated data analysis. However, despite all these variations, various researchers have always worked to develop an equivalent electrical model of the skin. The two most important categories of electrical models are RC‐based model and CPE‐based model which focus on the physiological stratification and biological properties of skin, respectively. In this work, experimental skin impedance data is acquired from ten sites on the body to find the fitting model. It is observed that a hybrid of fractional‐order CPE‐based model and higher‐order RC layered‐based model can provide the best fitting electrical model of skin. A new model is developed with this hybrid orders. Genetic algorithm is used for the extraction of parameter components. Least error of fitting has been observed for the proposed model as compared with the other models. This model can be used in correlating many skin problems and in the development of diagnostic tools. It will offer an additional supportive tool in‐vitro to the medical specialist.Inspec keywords: genetic algorithms, skin, data analysis, bioelectric phenomena, medical computing, electric impedance, patient diagnosisOther keywords: skin impedance models, human skin impedance, skin impedance analysis, data analysis, electrical models, RC‐based model, biological properties, experimental skin impedance data, fractional‐order CPE‐based model, skin problems, complex biological tissue, higher‐order RC layered‐based model, genetic algorithm, diagnostic tools     

Comparisons of polymer/gas partition coefficients calculated from responses of thickness shear mode and surface acoustic wave vapor sensors

Apparent partition coefficients, K, for the sorption of toluene by four different polymer thin films on thickness shear mode (TSM) and surface acoustic wave (SAW) devices are compared. The polymers examined were poly(isobutylene) (PIB), poly(epichlorohydrin) (PECH), poly(butadiene) (PBD), and poly(dimethylsiloxane) (PDMS). Independent data on partition coefficients for toluene in these polymers were compiled for comparison, and TSM sensor measurements were made using both oscillator and impedance analysis methods. K values from SAW sensor measurements were about twice those calculated from TSM sensor measurements when the polymers were PIB and PECH, and they were also at least twice the values of the independent partition coefficient data, which is interpreted as indicating that the SAW sensor responds to polymer modulus changes as well as to mass changes. K values from SAW and TSM measurements were in agreement with each other and with independent data when the polymer was PBD. Similarly, K values from the PDMS-coated SAW sensor were not much larger than values from independent measurements. These results indicate that modulus effects were not contributing to the SAW sensor responses in the cases of PBD and PDMS. However, K values from the PDMS-coated TSM device were larger than the values from the SAW device or independent measurements, and the impedance analyzer results indicated that this sensor using our sample of PDMS at the applied thickness did not behave as a simple mass sensor. Differences in behavior among the test polymers on SAW devices are interpreted in terms of their differing viscoelastic properties.     

Comparisons of Kt/V evaluated using an online method and calculated from urea measurements in patients on intermittent hemodialysis

Kt/V(urea) (Kt/V) depends on the method applied for its evaluation. Our aim was to compare Kt/V obtained using the conductivity online method and that calculated from urea measurements. Studies were carried out in 40 patients. A stable dialysis schedule was maintained during the study. Online Kt/V was measured every week or 4 consecutive months. Single pool Kt/V (spKt/V) was calculated from urea estimations in the fourth week of the first month and in the last week of the fourth month of studies, using the formulas: (1)spKt/V = -ln(Ct/Co), where Ct is the postdialysis urea concentration obtained at the end of dialysis, Co the predialysis urea concentration obtained before the start of the blood pump; (2)spKt/V = -ln(R - 0.008 x t - f x UF/W), where R is the Ct/Co, t the duration of HD session, f=1.0, UF is the ultrafiltration volume (l), W is the body weight after the HD session; and (3)spKt/V + -ln(R - 0.008 x t) + (4 - 3.5 x R) x UF/W. The equilibrated Kt/V (eKt/V) was calculated as (3)spKt/V - {0.47 x [(3)spKt/V]/t} + 0.02. Correlation analysis was performed between all obtained Kt/V. Weekly online Kt/V was stable during 4 months of studies. In the first month, the respective values of online Kt/V, (1)spKt/V, (2)spKt/V, (3)spKt/V, and eKt/V were 1.15+/-0.14, 1.16+/-0.14, 1.38+/-0.17, 1.36+/-0.20, and 1.22+/-0.13. In the fourth month, these values were 1.17+/-0.14, 1.16+/-0.17, 1.38+/-0.22, 1.35+/-0.20, and 1.22+/-0.18. The respective values of Kt/V, estimated in the first and fourth month, were not different and showed a positive correlation: the highest one occurred between online Kt/V estimated at the indicated study periods (r=0.713, p=0.0000). Online Kt/V was significantly lower than (2)spKt/V, (3)spKt/V, and eKt/V. Correlation coefficients between online Kt/V, spKt/V, and urea reduction ratio did not exceed 0.490. Our studies show that Kt/V obtained using online monitoring indicates a lower intermittent hemodialysis adequacy that those calculated from urea measurements. This difference has to be remembered in application of results to clinical practice.     

Statistical validation of WLAN range calculated with propagation models for industrial environments by chipset-level received signal strength measurements

The wireless range of an IEEE 802.11b/g system as predicted by an empirical model for path loss and temporal fading is validated statistically by measurements of the received signal strength or RSS reported by WLAN monitoring software. This validation is made for indoor industrial environments. In this work, a comparison between a link budget based on industrial propagation models and site surveys executed with WLAN monitoring software is made for two types of industrial environments, namely production centres and warehouses, and for three practically important 802.11b/g data rates of 2, 11 and 18 Mbps. In general, wireless ranges calculated with the link budget and extracted from the site survey measurements are in good agreement. An important finding is that in production centres, the site survey measurements show severe attenuation of the 802.11b/g signal in the presence of large obstacles with approximately the same height as the access point. This phenomenon can cause a noticeable overestimation of the real wireless range by the link budget. Furthermore, it is shown that changing the receiving antenna?s height between 0.5, 1.5 and 2 m has only very limited effect on the wireless range.     

Evaluation of absorbed doses in voxel-based and simplified models for small animals

Internal dosimetry in non-human biota is desirable from the viewpoint of radiation protection of the environment. The International Commission on Radiological Protection (ICRP) proposed Reference Animals and Plants using simplified models, such as ellipsoids and spheres and calculated absorbed fractions (AFs) for whole bodies. In this study, photon and electron AFs in whole bodies of voxel-based rat and frog models have been calculated and compared with AFs in the reference models. It was found that the voxel-based and the reference frog (or rat) models can be consistent for the whole-body AFs within a discrepancy of 25%, as the source was uniformly distributed in the whole body. The specific absorbed fractions (SAFs) and S values were also evaluated in whole bodies and all organs of the voxel-based frog and rat models as the source was distributed in the whole body or skeleton. The results demonstrated that the whole-body SAFs reflect SAFs of all individual organs as the source was uniformly distributed per mass within the whole body by about 30% uncertainties with exceptions for body contour (up to -40%) for both electrons and photons due to enhanced radiation leakages, and for the skeleton for photons only (up to +185%) due to differences in the mass attenuation coefficients. For nuclides such as (90)Y and (90)Sr, which were concentrated in the skeleton, there were large differences between S values in the whole body and those in individual organs, however the whole-body S values for the reference models with the whole body as the source were remarkably similar to those for the voxel-based models with the skeleton as the source, within about 4 and 0.3%, respectively. It can be stated that whole-body SAFs or S values in simplified models without internal organs are not sufficient for accurate internal dosimetry because they do not reflect SAFs or S values of all individual organs as the source was not distributed uniformly in whole body. Thus, voxel-based models would be good candidates for dosimetry in non-human biota if further accuracy in environmental dosimetry is desired.     

Comparisons of bidirectional reflectance distribution function measurements on prepared particulate surfaces and radiative-transfer models

To understand the connection between single-particle optics and the optics of a closely packed surface, controlled laboratory measurements of bidirectional reflectance distribution functions on layers of polymer and glass spheres are carried out. The measurements are compared with predictions from five radiative-transfer models; the Hapke's models, the Lumme-Bowell model, the BRF algorithm of Mishchenko et al., and the discrete ordinate radiative transfer. It is found that models of strict numerical radiative-transfer equations (RTEs) predict measurements well in some regions but have errors in both forward- and backward-scattering directions. The improved Hapke's model, although it has an anisotropic multiple-scattering term, still produces considerable errors compared with the strict RTE. The difference can be attributed to the exclusion of a diffraction contribution in the Hapke model.     

Effect of Contact Time of Liquid Radioactive Waste with Bed Rock of Underground Repository on Migration Behavior of 90Sr, 137Cs, 239Pu,and 241Am

Behavior of radionuclides caused by interaction of acidic waste with sandy bedrock in deep underground repositories is studied, including sorption-desorption of ⁹⁰Sr, ¹³⁷Cs, ²³⁹Pu, and ²⁴¹Am. The amount of mobile forms of radionuclides decreases with increasing contact time with bedrock, thus decreasing the migration rate of the radionuclides in the collector bed.     

Kinetics of Reactions of Np and Pu Ions with Hydrazine Derivatives: XVII. Reaction of Pu(VI) with Hydroxyethylhydrazine

Reduction of Pu(VI) to Pu(III) with hydroxyethylhydrazine (HOC₂H₄N₂H₃) in HNO₃ solutions involves the following consecutive steps²: Pu(VI) + HOC₂H₄N₂H₄ Pu(V) + ...; Pu(V) + HOC₂H₄N₂H₄ ⁺ Pu(IV) + ...; Pu(V) + Pu(III) 2Pu(IV); and Pu(IV) + HOC_2H4N₂H₄ ⁺ Pu(III) + .... The overall kinetic equations of these steps were suggested, and their rate constants and activation energies were determined. The mechanisms of the four reaction steps, consistent with the experimental kinetic data, are discussed.     

Oxidation of Pu(VI) with ozone and stability of the oxidation products,Pu(VII) and Pu(VIII), in concentrated alkali solutions

Oxidation of Pu(VI) with ozone and stability of the oxidation products, Pu(VII) and Pu(VIII), in 4–15 M NaOH solutions were studied. In a wide range of alkali concentrations, from 1 to 15 M, the Pu(VI) ozonation yields a mixture of Pu(VII) and Pu(VIII). It was proved that Pu(VII) exists in aqueous alkali solutions in the form different from that suggested previously. Pu(VII) is readily reduced with ?2? in aqueous alkali solutions with the NaOH concentration of up to 8 M, whereas at [NaOH] + 8 M it is fairly stable. On the contrary, Pu(VIII) is noticeably reduced with water at room temperature throughout the examined range of NaOH concentrations from 1 to 15 M.     

Use of faecal excretion function for quick estimation of initial and existing lung burden for occupational exposure control due to 239Pu for S-class of intake

Two functions namely initial lung deposition and lung retention per unit faecal excretion rate are constructed primarily based on the excretion pattern of four subjects exposed to (239)Pu. In the absence of initial clear knowledge about the class of compound inhaled, faecal to urine excretion ratio was used to infer the type of inhaled class. Trends in the urine and faecal data had suggested that the intake was due to mixed class of plutonium compound for each case. With the assumption of 1:1 mixture of plutonium M&S class inhaled compound, faecal excretion rates for only S-class intake were worked out. Uptake inferred based on their urinary data had suggested it to be of similar level within 40% of uncertainty for 5 microm particle size distribution. Data, all the four cases, were pooled for analysis citing the similar level of intake, particle size distribution, nature and pattern of work. The function obtained was tested for S-class lung retention and faecal excretion rate value. These functions are handy tool for estimating initial lung burden and lung retention value for low level of S-class plutonium intake based on subject faecal analysis data.