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At least 19 recordsLinked to original sources
PubMed1989

Measurement of natural radioactivity levels in Indian foodstuffs by gamma spectrometry.

Measurements of natural radioisotopes present in some of the foodstuffs which form the main components of the composite Indian diet are presented. Assessment of daily intake of these natural radionuclides has been made on the basis of the average daily intake of these food-items by the population of Bombay and its environment. The content of 40K, 226Ra and 228Th radioactivity varies from 45.9 to 649.0 Bq/kg, 0.01 to 1.16 Bq/kg and 0.02 to 1.26 Bq/kg, respectively. The average daily intakes of 40K, 226Ra and 228Th have been estimated as 105.6, 0.17 and 0.18 Bq d(-1), respectively for the period 1970-1982.

Eating↗
PubMed1990

In situ detection of cutaneous melanoma by prompt gamma-ray spectrometry using melanoma-seeking 10B-dopa analogue.

10B1-para-boronophenylalanine (10B1-BPA), one of our boronated dopa analogues developed for thermal neutron capture therapy, has been found to have a selective affinity for malignant melanoma. We have established a method of 'in situ' detection of subcutaneous melanoma lesions, using this melanoma-seeking 10B-labeled compound. In this study, we applied an 'in situ' 10B microanalysis system via detection of the prompt gamma-ray from the 10B(n, alpha)7Li reaction triggered by irradiating the 10B-containing target with pure thermal neutrons, called prompt gamma-ray spectrometry, to hamsters bearing Greene's melanoma in subcutis and to a human patient whose occipital subcutaneous tumor was suspected of being a metastatic melanoma. In the hamsters, the time-dependent 10B dynamics showed increased 10B accumulation in melanoma, after 10B1-BPA administration, in contrast to that in non-melanoma normal skin. In the human patient, after subcutaneous injection of 10B1-BPA into perilesional sites 4 cm distant from the tumor margin, the average 10B concentration in the tumor was determined to be 24 ppm (microgram/g), in contrast to 3 ppm in skin covering the tumor and 1.1 ppm in blood, indicative of selectively high 10B1-BPA uptake by the tumor.

Aged↗
PubMed1990

[Radioactivity levels in mushrooms collected in the area of Karlsruhe during 1987 and 1988].

Radioactive contamination of wild-growing mushrooms collected in the Northern Black Forest and neighbouring Rhine Valley area has been monitored since the Chernobyl reactor accident. Cs-134, CS-137, Ag-100m and the natural nuclide K-40 were determined by gamma-spectrometry. Pooled data from all species and all locations showed a decrease in the radio-caesium levels from 1986 to 1988, both in mean values and maximum values. Samples of the same species collected at the same location exhibited large differences, although mixed samples rather than individual mushrooms were measured. Accumulation of caesium was observed particularly in Laccaria amethystina, Xerocomus badius, Xerocomus chrysenteron, Cantharellus tubaeformis, Laccaria laccata, and Russula ochroleuca, with maximum values of 3600 (1986), 2000 (1987), and 1200 (1988) Bq/kg of radiocaesium. A large number of species, among them Calocybe gambosa and Coprinus comatus, showed very small accumulations or no caesium. An accumulation of silver was found in Macrolepiota rhacodes and Agaricus arvensis, which contained a maximum of 11 Bq/kg Ag-110m.

Accidents↗
PubMed1991

In vivo analysis of intracellular thallium-201 accumulation in skeletal muscle of the rat.

The specific accumulation of the K(+)-analogue Tl+ (201Tl+) in muscle after intramuscular injection was analysed by gamma spectrometry in vivo of rat hamstring muscles. A mixture (0.1 ml) of 201Tl+ (thallous+ chloride-) and 99mTc-pertechnetate- (Na+ pertechnetate-) was given, by which 99mTc-pertechnetate- served as a reference substance with negligible intracellular accumulation. After 30 min 8.9 +/- 5.8% of injected 99mTc-pertechnetate- remained in the muscle and 49 +/- 10% of 201Tl+ (+/- SD, n = 18). The difference between 201Tl+ and 99mTc-pertechnetate- at 30 min was taken as a measure of the intracellular 201Tl+ accumulation, which was 40% of the initial amount of 201Tl+. The half-time of the calculated intracellular 201Tl+ accumulation was 4.9 +/- 1.9 min. In the presence of ouabain (1.0 mM in the injectate) the intracellular 201Tl+ accumulation was 25 +/- 10% (n = 7), that is ouabain decreased the intracellular 201Tl+ accumulation by 38% (P = 0.0035). Non-radioactive Tl+ (1.0 mM Tl-acetate in the injectate) inhibited the uptake by 35% (P = 0.0013). Ouabain did not significantly affect the half-time for the Tl+ uptake. An increase in [K+] of the injectate from 0 to 5 mM had no significant effect. Insulin (0.2 units in the injectate) had no effect. It is concluded that the specific Tl(+)-accumulating properties of muscle fibres can be studied with the present in vivo technique, which can provide information about the Na-K-ATPase activity and the membrane potential of muscle fibres.

Animals↗
PubMed1975

Renal blood flow distribution during steady-state exercise and exhaustion in conscious dogs.

To determine whether renal blood flow is reduced or redistributed during exercise, we measured total renal flow (TRF) and intrarenal flow distribution (IRFD) in nine dogs. They ran on a motor-driven treadmill at 3-8 mph at grades of 8-15% for an average of 35 min. We measured aortic pressure, heart rate, stroke volume, and cardiac output (CO) via chronically implanted catheters and an electromagnetic flow probe. We injected 15-mum radiolabeled microspheres (85Sr, 141Ce, and 51Cr) via a left atrial catheter during resting control, steady state (SS) and exhaustive (EE) exercise; measured their distribution by gamma spectrometry; and determined TRF as % CO and as ml/100 g per min. We determined IRFD for the outer and inner cortex and the outer medulla. TRF as %CO dropped (P less than 0.05) during both levels of exercise: from 10.2 +/- 0.7% to 3.9 +/- 0.4% (SS) and 3.4 +/- 0.6% (EE). TRF in ml/100 g per min did not change significantly from control (228 +/- 30 ml/100 g per min). IRFD was unchanged with exercise, remaining at about 80, 20, and 3% of TRF for the outer and inner cortex and outer medulla, respectively. We conclude that blood flow is not diverted from the kidneys during severe exercise in the dog.

Animals↗
PubMed1978

[The gamma ray peak efficiency determination for volume samples using a radioactive point source (author's transl)].

The peak efficiencies for volume samples in gamma spectrometry of environmental radioactive materials have been determined using a radioactive standard point source. The advantages of the method, as compared with conventional calibration method using standard volume sources, are as follows; 1) The peak efficiencies can be obtained with high accuracy and precision, 2) To be applied easily to any sample container being axial symmetry, 3) The correction for self-absorption can be performed by the simple calculation. On the other hand, the application of the method is restricted to only the cylindrical or coaxial detector.

Mathematics↗
PubMed1975

Gamma-ray spectrometry data collection and reduction by simple computing systems.

The review summarizes the present state of the involvement of relatively small computing devices in the collection and processing of gamma-ray spectrum data. An economic and utilitarian point of view has been chosen with regard to data collection in order to arrive at practically valuable conclusions in terms of feasibility of possible configurations with respect to their eventual application. A unified point of view has been adopted with regard to data processing by developing an information theoretical approach on a more or less intuitive level in an attempt to remove the largest part of the virtual disparity between the several processing methods described in the literature. A synoptical introduction to the most important mathematical methods has been incorporated, together with a detailed theoretical description of the concept gamma-ray spectrum. In accordance with modern requirements, the discussions are mainly oriented towards high-resolution semiconductor detector-type spectra. The critical evaluation of the processing methods reviewed is done with respect to a set of predefined criteria. Smoothing, peak detection, peak intensity determination, overlapping peak resolving and detection and upper limits are discussed in great detail. A preferred spectrum analysis method combining powerful data reduction properties with extreme simplicity and speed of operation is suggested. The general discussion is heavily oriented towards activation analysis application, but other disciplines making use of gamma-ray spectrometry will find the material presented equally useful. Final conclusions are given pointing to future developments and shifting their centre of gravity towards improving the quality of the measurements rather than expanding the use of tedious and sophisticated mathematical techniques requiring the limits of available computational power.

Activation Analysis↗
PubMed1979

Gamma-ray spectrometry of humans at the University of Utah.

A human total-body counter was designed and built with two 20 X 10 cm NaI (Tl) crystals suspended over an "isoresponse surface" upon which the subject reclines. This surface is curved from head to knee and from left to right, so that a gamma-ray emitting object is detected with equal efficiency when placed anywhere upon it. The positioner and detectors are housed in a low background enclosure constructed of steel 31 cm thick with a graded inner lining of lead + cadmium + copper. Calibration of the system was accomplished by administering trace amounts of various radionuclides to 48 human subjects of various sizes, ranging in age from 4--80 years. Counting rates per retained muCi at 0.53, 0.66, 1.53, and 2.75 MeV (83Rb, 137Cs, 42K, and 24Na) were determined as a function of body size and were compared with counting rates per muCi of corresponding emitters centered in a polyethylene cylinder of radius 10.3 cm. Limits of detection, corresponding to three times the standard deviation of a 50 min background, were 170 nCi 90Sr (via Bremsstrahlung X-rays), 0.78 nCi 131I, 0.48 nCi 83Rb, 0.52 nCi 137 Cs, 4.9 nCi 40K (or 5.8 g of natural potassium) and 1.7 nCi 222Rn.

Body Height↗
PubMed1990

MIC-III--an integrated software package to support experiments using the radioactive microsphere technique.

MIC-III is a versatile program system to support gamma spectrometry data management and data collection for experiments using the radioactive microsphere technique. It is mainly written in PASCAL and running on a minicomputer. Hierarchical organ dissection schemes are used for unique classification and identification of samples. For each series of experiments, up to 12 different nuclides and up to 20 different organ dissection schemes can be handled simultaneously. Sample weights are collected on-line and sample radioactivities are measured automatically by gamma spectrometry under process control. The spectra with a resolution of 1022 channels are analyzed using a modified linear regression technique and a strategy to compensate for global spectrum shifts. The spectrum deconvolution algorithm was evaluated by calculating the recovery indices for known nuclide mixtures and compared to the stripping method, matrix method and a linear regression technique using window counts. Recovery values produced by MIC-III are better balanced than those of the other methods. MIC-III showed the smallest dispersion of the recovery index and exhibited least error accumulation in case of spectrum shift. MIC-III computes regional blood flow and arterio-venous shunt, and provides interfaces to customized programs or statistical software packages for further analysis. It has successfully been employed in more than 140 experiments.

Animals↗
PubMed1992

In-situ determination of deposited radionuclide activities: improved method using derived depth distributions from the measured photon spectra.

When applying the standard method of in-situ gamma spectrometry to determine deposited radionuclide activities, an assumption is needed regarding the depth distribution of radionuclides in the ground. The method can be improved by assessing, from information contained in the spectrum, the attenuation of the radiation by the soil and vegetation. By comparing the count rates of the x ray and the gamma-ray lines of its daughter nuclide 137mBa, the 137Cs activity per area can be determined. The range of applicability of the method is discussed by means of an uncertainty analysis, and the method is applied to post-Chernobyl measurements. A comparison with the results of the standard method of in-situ spectrometry demonstrates the progress achieved by the proposed method. Nevertheless, the method still has some shortcomings for the peak analysis that could be improved by better detector resolution or better computer software.

Cesium Radioisotopes↗
PubMedDate not supplied

Production of 134Cs thermo-generated aerosols. Study of their behavior after deposition on spruce trees.

This paper presents observations made on the behavior of radioactive cesium in laboratory conditions. 134Cs-loaded aerosols are generated from UO2 pellets in an electric oven and allowed to deposit on small spruce trees. The transfer of radioactivity to the plants has been studied. In another series of experiments, trees are submitted to artificial rain contaminated by the radioactive aerosols. The two modes of contamination are compared.

Accidents↗