Low-level activity measurement of 131Xem, 133Xem, 135Xe and 133Xe in atmospheric air samples using high-resolution dual X-gamma spectrometry.

High-resolution dual X and gamma spectrometry has been optimized to improve the sensitivity in analyzing radioxenon from environmental samples, especially for the metastable isotopes (131Xem and 133Xem). The full-energy peak (FEP) efficiency curve in the 20-700 keV range has been established with a global uncertainty better than +/-3% using a Monte Carlo simulation. The minimum detectable activity concentrations (MDC) achievable at the laboratory for 131Xem, 133Xem, 133Xe and 135Xe are presented and the influence of 133Xe activity on the metastable radioxenon MDCs is evaluated.     

Evaluation of an integrated 133Xe regional pulmonary-function analyzer.

An integrated system for diagnostic, quantitative, static and dynamic, regional pulmonary-function analysis--both ventilation and perfusion--using 133Xe has recently been developed by Ohio-Nuclear. This paper considers this equipment in a clinical setting and describes the results obtained from 50 normal subjects. Functionally, the analyzer was found to be satisfactory and its operation simple and easy to learn. Patient discomfort is minimal and the complete ventilation-perfusion analysis can be performed and reported in less than 30 min. The results from normal subjects were comparable with published results.     

Characterization of 133Xe gas washout in pulmonary emphysema with dynamic 133Xe SPECT functional images

PURPOSE: To characterize regional ventilation impairment of pulmonary emphysema using dynamic 133Xe single photon emission computed tomography (SPECT) functional images, compared with other forms of chronic obstructive pulmonary disease (COPD). METHODS: Dynamic 133Xe SPECT was performed in 34 patients with emphysema and 15 patients with other forms of COPD. Three-dimensional voxel-based functional images of the half-clearance time (T1/2) mainly reflecting the initial rapid washout of 133Xe gas from the large airways, and of the mean transit time (MTT) reflecting 133Xe gas washout from the entire lungs, including the small airways and alveoli, were created based on an area-over-height method. T1/2 and MTT values were compared with the regional extent of low attenuation areas (%LAA) on density-mask computed tomography images and the diffusing capacity of the lungs for carbon monoxide (DLCO). RESULTS: The MTT/T1/2 ratio in each lung in emphysema was significantly higher than that in other forms of COPD (1.60+/-0.74 vs. 1.21+/-0.26; P<0.01). In the selected unilateral lungs with similar T1/2 values, MTT values were also significantly higher in emphysema. MTT values in each lung showed a significantly closer correlation with the corresponding %LAA values compared with T1/2 values in emphysema (R=0.698, P<0.0001 vs. R=0.338, P<0.01; P<0.05); while only the T1/2 values showed a significant correlation in other forms of COPD (P<0.0001). In correlation with DLCO, MTT values showed a significantly closer correlation compared with T1/2 values in emphysema (R=0.909, P<0.0001 vs. R=0.555, P<0.001; P<0.05); while either value did not show a significant correlation in other forms of COPD. CONCLUSION: MTT values are more critically affected in emphysema compared with other forms of COPD without significant alveolar destruction, and MTT and T1/2 values appear to be differently correlated with the regional extent of LAA between these two disorders. Direct comparison of regional T1/2 and MTT values on functional images may contribute to the demarcation of lung pathology of these two disorders.     

Evaluation of 235U decay data

Evaluation of the complete decay scheme and data for ²³⁵U including new measurements are presented in this report; literature data available up to June 2008 are included. The half-life is determined to be (7.04±0.01)×10⁸ yr. All known measured γ-ray absolute intensities have been examined; the γ-ray emission probability of the reference γ-ray line of 185.72 keV is recommended to be 57.0±0.3%. The calculated internal conversion coefficients and their uncertainties have been used to obtain the complete decay intensity balance. The other decay characteristics are calculated using the ENSDF analysis program. Finally the new decay scheme for ²³⁵U is presented.     

Lateral-view ventilation images with 133Xe.

For better delineation of regional ventilation abnormalities, a lateral-view imaging has been employed when one or more areas of abnormal retention were visible in posterior views of 133Xe washout images. It is technically simple to obtain lateral views during the 133Xe washout phase. The resulting images were found to be very useful in detecting regions of ventilation-perfusion mismatch and in evaluating regional obstructive lung disease.     

Evaluation of 169Yb decay data.

This evaluation of the complete decay scheme of 169Yb sums up the recent measurements carried out during an international exercise in which 11 laboratories were involved, and also takes into account other independent experiments. As a result of the numerous high-quality measurements available, the decay scheme is shown to be highly consistent. The half-life is determined to be 32.018 (5)d, and the emission probabilities of the two reference gamma lines of 198 and 307 keV are recommended to be 35.93 (12)% and 10.046 (45)%, respectively.     

Evaluation the decay data of 153Gd

¹⁵³Gd decays to the excited states of ¹⁵³Eu through the electron capture decay mode. The evaluation of the complete decay scheme and data of ¹⁵³Gd including the recent new measurements are presented in this report. The limitation of relative statistical weight method (LRSW) was applied to average numbers throughout the evaluation. The uncertainty assigned to the average value was always greater than or equal to the smallest uncertainty of the values used to calculate the average. The half-life is determined to be 239.47±0.07 days. All known measured γ-ray relative emission probabilities have been examined. And the γ-ray emission probability of the reference γ line of 97.431 keV is recommended to be 29.5±0.5%. The calculated internal conversion coefficients and their uncertainties have been used to obtain the complete decay intensity balance. The other decay characteristics are calculated using the ENSDF analysis program. Finally the new ¹⁵³Gd decay scheme was re-built.     

Evaluation of 234Th nuclear decay data

²³⁴Th is a naturally occurring radionuclide being the daughter of ²³⁸U. This paper presents the results obtained in a new evaluation of the nuclear data characterizing the ²³⁴Th radioactive decay. The following decay characteristics have been evaluated: half-life, energies and probabilities of beta and gamma-ray transitions, internal conversion coefficients, energies and emission probabilities of gamma-rays, X-rays, conversion and Auger electrons. Some evaluation difficulties encountered have been pointed out. A new recommended absolute emission probability of 3.75 (8)% has been proposed for the main 63.3-keV gamma-ray in the ²³⁴Th decay. Some practical considerations of the ²³⁴Th activity determination by gamma-ray spectrometry are also presented.     

Evaluation of 233Pa decay data.

An evaluation of the complete scheme and data for (233)Pa decay, including results of the recent measurements, is presented. Several data evaluation procedures were used in the analysis of the half-life data. The half-life has been determined to be 26.971+/-0.013 days. All the gamma-ray emission probabilities ever published have been examined, and the gamma-ray emission probability for the reference 312-keV gamma line is recommended as 38.35+/-0.28%. The calculated internal conversion coefficients and their uncertainties have been used to obtain the complete decay intensity balance. Other decay characteristics have been calculated using the ENSDF analysis program. Finally, a new (233)Pa decay scheme has been built.     

Evaluation of 225Ac decay data.

Evaluation of the complete decay scheme and data for (225)Ac including new measurements are presented in this report; literature data available up to March 2006 are included. The half-life is determined to be 10.0+/-0.1 days. All known measured gamma-ray relative intensities have been examined; the gamma-ray emission probability of the reference gamma-ray line of 150.04 keV is recommended to be 0.693+/-0.012%. The calculated internal conversion coefficients and their uncertainties have been used to obtain the complete decay intensity balance. The other decay characteristics are calculated using the ENSDF analysis program. Finally, the new decay scheme for (225)Ac is presented.     

The decay of 133mXe.

The decay of (133m)Xe has been re-measured using an electron-transporter spectrometer and a planar HPGe detector. The sample of (133m)Xe was produced by means of proton-induced fission using an ion-guide based on-line mass separator. The deduced K and L+M+... shell conversion coefficients, alpha(Kappa)=6.5(9) and alpha(L+M+...)=2.9(4), agree within the uncertainty limits with the theoretical values and remove the inconsistencies between the previous experimental studies of (133m)Xe.