SEARCH · PubMed Health

Results for “SCINTILLATION COUNTER”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 541 records · Page 30Linked to original sources

PubMed1993

Metabolism of injected plutonium in two healthy men.

The metabolism of plutonium has been studied following intravenous injection of 237Pu as Pu (IV) citrate into two healthy male volunteers. Measurements of the tracer in samples of blood and excreta were made by gamma-ray spectrometry, and patterns of organ uptake were investigated through serial measurements with a scintillation counter viewing the liver and selected skeletal sites. Excretion in urine and feces measured during the first 3 wk accorded closely with the patterns deduced by Durbin from the report of Langham et al. on patients injected with 239Pu. However, concentrations in blood were roughly twice those suggested by Durbin during most of the 14 d covered by our measurements. In one subject, the liver deposit increased to a plateau after about 21 d, at roughly 55% of the injection; in the other, the increase was prolonged, reaching about 70% after several months.

Aged↗

PubMed1993

Simultaneous quantitative determination of 3H, 14C, 32P, 35S, 51Cr, and 125I on the surface of a paper disc using combustion.

A paper disc that retained 3H, 14C, 32P, 35S, 51Cr, and 125I on its surface was combusted in a flow-type combustion flask filled with oxygen. The combustion products containing five radionuclides, except 14CO2, were collected by washing the inner wall of the flask with 0.5-M hydrogen peroxide containing excess NaHSO3. The 14CO2 that remained in the gas phase of the flask was introduced into another flask for absorption into an organic base solution. By determining the radioactivity of both the solutions containing the respective radionuclides by means of NaI(Tl) and liquid scintillation counters, the six radionuclides in the solutions were quantified. The detection limit of surface contamination with this method was compared with the limit specified by Japanese law for the surface contamination of controlled areas.

Fires↗

PubMed1994

Systematic indoor radon and gamma measurements in kindergartens and play schools in Slovenia.

Systematic measurements of indoor radon concentrations and gamma dose rates were carried out in the 730 kindergartens and play schools in Slovenia that, together, care for 65,600 children. The main method for indoor radon measurement was direct sampling in alpha scintillation cells, but in cases with an increased instantaneous radon concentration, the additional methods of track-etch detectors and alpha spectroscopy were applied. In 528 kindergartens and play schools (72%), radon concentrations were below 100 Bq m-3, with a geometric mean of 58 Bq m-3. In 16 kindergartens and play schools (2.2%), radon concentrations exceeded 800 Bq m-3. In all cases, the main reason for a high indoor radon concentration was the geological structure of the soil. Gamma dose rates were measured with a portable scintillation counter, but in the Ljubljana region thermoluminescence dosimeters were also exposed. The results ranged from 30 to 295 nGy h-1, with a geometric mean of 88 nGy h-1.

Air Pollution, Indoor↗

PubMed2000

Systematic indoor radon and gamma-ray measurements in Slovenian schools.

During the winter months of 1992/93 and 1993/94, instantaneous indoor radon concentrations and gamma dose rates were measured in 890 schools in Slovenia attended in total by about 280,000 pupils. Under "closed conditions," the room to be surveyed was closed for more than 12 h prior to sampling, the air was sampled into alpha scintillation cells with a volume of 700 cm3, and alpha activity was measured. An arithmetic mean of 168 Bq m(-3) and a geometric mean of 82 Bq m(-3) were obtained. In 67% of schools, indoor radon concentrations were below 100 Bq m(-3), and in 8.7% (77 schools with about 16,000 pupils) they exceeded 400 Bq m(-3), which is the proposed Slovene action level. In the majority of cases, radon concentrations were high due to the geological characteristics of the ground. Approximately 70% of schools with high radon levels were found in the Karst region. Gamma dose rates were measured using a portable scintillation counter. An arithmetic mean of 102 nGy h(-1) and a geometric mean of 95 nGy h(-1) were obtained. No extraordinarily high values were recorded.

Adolescent↗

PubMed2000

Elements of a portable radiation detector calibration program.

The Department of Environmental Health & Safety at San Diego State University (SDSU) calibrates portable radiation detectors as a service to the university's research community. SDSU's calibration program was developed and implemented based on selected recommendations provided by the American National Standards Institute and the National Council on Radiation Protection and Measurements. This paper outlines the elements of the calibration program including, technical references and the rationale for program development. Covered under the provisions of this paper include those instruments used to evaluate the dose rates from radioactive materials and those instruments used to determine radioactive contamination or uptake. Those detectors specifically not addressed are liquid scintillation counters, semi-conductors, neutron dose rate instruments, and instruments intended for quantifying dose rates due to beta emission.

Calibration↗

PubMed2003

Results of surveys at United States pulp and paper mills for the presence of scales and precipitates containing naturally occurring radioactive material (NORM).

Field surveys were carried out at sixteen pulp and paper mills in the United States--seven kraft process, two sulfite process, and seven recycling process mills--for the presence of naturally occurring radioactive material (NORM) in precipitates and scales. NORM was detected at three of the kraft mills, one sulfite mill, and none of the recycling mills. At one of the kraft mills, the NORM was associated with a commercial aluminum sulfate ("alum") slurry used on the paper machines and in intake water treatment. The maximum activity level of this alum scale was 252,000 Bq kg(-1) (6,800 pCi g(-1)) 228Ra. At two kraft mills, NORM was associated with precipitates in the bleach plant. The measured NORM activity in samples of these scales was approximately 44,400 Bq kg(-1) (1,200 pCi g(-1)) 226Ra. Where NORM was detected at a sulfite mill, the NORM deposits were found adhering tightly to the surfaces of brownstock washers. Although samples were not removed for radionuclide analysis, survey readings at the drum surface were 26 nC kg(-1) h(-1) (100 microR h(-1)) with a scintillation counter and 2,200 cpm with a Geiger-Muller counter. At all mills, exposure rate measurements and risk assessment calculations indicated that it would be highly unlikely for any worker's annual exposure to exceed 1 mSv (100 mrem) (the Nuclear Regulatory Commission limit for untrained workers) due to exposure to these materials.

Background Radiation↗

PubMed1996

Adrenomedullin as a novel antiproliferative factor of vascular smooth muscle cells.

OBJECTIVE: The present study was designed to examine whether adrenomedullin affects fetal calf serum (FCS)-stimulated proliferation in cultured rat vascular smooth muscle cells (VSMCs). METHODS: Rat VSMCs were grown from explants of Sprague-Dawley rat aorta and were grown using the standard cell culture method. After incubation for 24 h with various concentrations of adrenomedullin in the presence of 5% FCS, trichloroacetic acid-insoluble tritiated thymidine was measured in a liquid scintillation counter. After incubation for 48 h, cell counts were performed. Cyclic adenosine 3',5'-monophosphate (AMP) levels were determined by radioimmunoassay. RESULTS: Rat adrenomedullin exhibited concentration-dependent inhibition of the FCS-stimulated increase in thymidine incorporation between 10(-7) and 10(-9) mol/l and of cell number at 10(-7) mol/l. However, the calcitonin generelated peptide (CGRP) receptor antagonist human CGRP(8-37) abolished these antiproliferative effects of rat adrenomedullin. Inhibition by adrenomedullin of FCS-stimulated cellular proliferation was paralleled by an increase in the cellular level of cyclic AMP. 8-Bromocyclic AMP, a cyclic AMP analogue, and forskolin, an activator of adenylate cyclase, inhibited the FCS-stimulated increase in thymidine incorporation and cell number. CONCLUSIONS: These results suggest that adrenomedullin inhibits FCS-stimulated proliferation in cultured rat VSMCs, probably through a cyclic AMP-dependent process. Taken together with the finding that adrenomedullin is synthesized in and secreted from vascular endothelial cells, adrenomedullin may play a role as an antiproliferative factor for VSMCs in a paracrine fashion.

8-Bromo Cyclic Adenosine Monophosphate↗

PubMed1995

A direct measurement of strontium-89 activity in bone metastases.

The total absorbed dose after systemic administration of 89Sr has been determined by measuring directly its activity in bone metastases. Autoradiography was performed on sections of bones obtained from patients treated with 89Sr to study the pattern of deposition. Discs of 5 and 8 mm diameter were cut from metastatic sites and normal bone. The beta-ray activity was determined with a scintillation counter, which was calibrated using similar bovine cancellous bone discs, onto which a known activity of 89Sr was transferred by pipette. From the activity measured, the initial activity (at the time of 89Sr administration) was calculated. The absorbed dose was estimated using the methodology described in NCRP Report No. 58. The estimated initial activity of 89Sr in the bone metastases varied from 2.3 to 240 MBq kg-1, with a mean value of 31 +/- 27 MBq kg-1. The total absorbed dose ranged from 1.3 to 64 Gy, with a mean of 18 +/- 16 Gy. The average total dose to normal bone sites was 1.1 +/- 0.4 Gy. The metastases to normal bone dose ratio in individual samples varied from 8 +/- 4 to 40 +/- 25. These estimates are in agreement with those obtained previously by indirect methods.

Autoradiography↗

PubMed2003

Estimation of thyroid mass in Graves' disease by a scintigraphic method.

scintigraphic method for the estimation of the thyroid mass in patients with Graves' disease is described. The method was first standardized using thyroid phantoms with eight different volumes ranging from 5 to 110 cm(3). The planar and single photon emission computed tomography (SPECT) images of each phantom were acquired with four different activities [3.7 MBq (100 microCi), 11.1 MBq (300 microCi), 22.2 MBq (600 microCi) and 37 MBq (1.0 mCi) of 99mTc-pertechnetate] with a 20% window symmetrically placed over the photopeak of 99mTc. The thyroid lobes were enclosed with the help of regions of interest (ROI) tools and a threshold was selected to identify the thyroid boundaries. The same threshold was used in all slices of an image. In the phantom study, a 20% threshold for planar images and a 30% threshold for SPECT were found to be optimum for measuring the thyroid volume. The volume from planar images was calculated by the formula described by Allen and Goodwin (The scintillation counter as an instrument for in-vivo determination of thyroid weight. Radiology 1952; 58: 68-79), whereas, in SPECT images, the sum of the slice areas was multiplied by the slice thickness. The estimated volume of each phantom was compared and correlated with its actual volume. After standardization of the technique with phantom studies, planar scintigraphy (with 20% threshold) in 51 patients and SPECT (with 30% and 35% threshold) in 40 patients with Graves' disease were performed to estimate the thyroid size. The thyroid size was also estimated by ultrasonography, which showed good agreement with the scintigraphic method, particularly with SPECT.

Graves Disease↗

PubMed2004

Measurement of the extraction fractions of nanocolloid and polyclonal immunoglobulin by axillary lymph nodes in patients with breast cancer.

BACKGROUND: 99mTc nanocolloid (99mTc-NC) is the most widely used tracer for lymphoscintigraphy, although others have been proposed, including radiolabelled proteins such as human serum albumin and polyclonal human immunoglobulin G (HIG). The extraction fraction of such tracers by individual nodes is clearly important but has not previously been measured in humans. METHODS: Patients scheduled for axillary clearance surgery (three groups) received dual-labelled radiotracers 2-4 h before surgery: group 1 (3 patients) received 99mTc-NC (10 MBq) and 111In-HIG (2 MBq) as a mixture (0.2 ml) into the breast parenchyma above the primary tumour; group 2 (3 patients) received 99mTc-HIG (10 MBq) and 111In-HIG (2 MBq) as a mixture (0.2 ml) into the breast parenchyma above the primary tumour; and group 3 (4 patients) received 99mTc-HIG (10 MBq) and 111In-HIG (2 MBq) separately (both 0.2 ml) into the breast parenchyma above the tumour and the intradermal plane at the areola. All resected nodes were counted for Tc and In in a well-type scintillation counter. In group 1, nodes were ranked according to their Tc uptake. In groups 2 and 3, nodes were ranked separately according to their respective Tc and In uptakes. If nodes are arranged in linear order and each node extracts a constant fraction of incoming tracer, then the activity in the nodes would decrease exponentially with an individual nodal extraction fraction, E, equal to 1-e(-k), where k is the rate constant of decrease. RESULTS: In the first group, 99mTc-NC and 111In-HIG identified the same sentinel and second echelon nodes. The observed decrease in nodal activity was exponential in all groups, at least for the first five nodes. Average values for E, based on the first five nodes were 0.69 (range 0.57-0.89; n=3) for 99mTc-NC and 0.45 (0.15-0.70; n=17) for HIG (irrespective of label) (Wilcoxon rank sum, P=0.02). With respect to HIG, there was no significant difference in E between 99mTc and 111In or between deep and superficial injections in group 3. CONCLUSION: Although HIG has an extraction fraction less than 99mTc-NC, the value of E is still high enough to make HIG a useful tracer for lymphoscintigraphy, especially for identifying second echelon nodes in addition to sentinel nodes and for imaging lymphatic vessels as well as lymph nodes.

Aged↗

PubMed2005

A comparison of techniques for analysing 90Y-Zevalin thin-layer chromatography plates.

OBJECTIVES: To simulate 90Y-Zevalin thin-layer chromatograms representing a range of radiochemical purities, to compare the radiochemical purities obtained with five techniques used to quantify 90Y on the plates and to measure the reproducibility of the five techniques at the minimum acceptable radiochemical purity of 95%. METHODS: Yttrium-90 solutions were pipetted onto the origin and solvent front lines of thin-layer chromatography (TLC) plates to simulate radiochemical purities of 90%, 92%, 94%, 95%, 96%, 98% and 100%. Each plate was analysed using three TLC scanners (Bioscan AR2000, Bioscan Mini-scan and an instrument constructed in-house) and two cut-and-count techniques: one using a sodium iodide well detector and the other a liquid scintillation counter. The reproducibility of each technique was measured by analysing the 95% plate 10 times. RESULTS: The radiochemical purities measured by the five techniques agreed well. The means of the seven results obtained with each agreed within 0.7%. The reproducibility of each technique was excellent. The coefficient of variation for 10 measurements was < or =0.3%. The signal to background ratios were satisfactory, ranging from 24 to 2.1 x 10(5). CONCLUSION: Each technique is suitable for analysing 90Y-Zevalin TLC plates.

Antibodies, Monoclonal↗

PubMed2002

Sevoflurane reduces synaptic glutamate release in human synaptosomes.

Volatile anesthetics reduce excitatory synaptic transmission in the mammalian brain. In the present study, the effect of sevoflurane on synaptic glutamate release, free cytosolic Ca2+ ([Ca2+]i), and glutamate uptake was investigated using isolated presynaptic terminals prepared from human cerebral cortex. The tissue was obtained from standard temporal lobe specimens removed because of epilepsy. The glutamate release and [Ca2+]i was measured as the fluorescence of nicotinamide adenine dinucleotide phosphate (NADPH) and fura-2, respectively. The uptake of radiolabeled glutamate was measured in a beta-scintillation counter. Membrane depolarization with 4-aminopyridine for three minutes evoked a Ca2+-dependent glutamate release of 3.4 +/- 0.5 nmol/mg. Sevoflurane 2.5 and 4.0% attenuated the evoked release by 45 and 55%, respectively. The evoked increase in [Ca2+]i was not significantly altered by the anesthetic agent. The uptake studies were performed in the high-affinity area, and Km was calculated to 19.3 +/- 5.7 x 10(-6) M and Vmax to 5.7 +/- 1.0 micromol g(-1) min(-1). The Km and Vmax values were not significantly altered by sevoflurane 2.5%. These results demonstrate that sevoflurane in the human brain reduces Ca2+-dependent glutamate release. The exact mode of action is still to be resolved.

4-Aminopyridine↗

PubMed2004

Validity of sentinel lymph node concept for patients with prostate cancer.

PURPOSE: We investigated the feasibility and validity of the sentinel lymph node concept for patients with prostate cancer. MATERIALS AND METHODS: A total of 24 patients (mean age 68.1 years) with prostate cancer but without detectable distant metastases were enrolled in this study. Radioactive tracer (technetium labeled phytate) was injected into the prostate 5 to 6 hours before surgery. Preoperative lymphoscintigraphy was viewed, and in vivo and ex vivo gamma probing was performed during the surgery, which included backup extended lymph node dissection. Radioactivity of the excised lymph nodes was measured and validated with an autowell scintillation counter. RESULTS: Radioactive positive (hot) nodes were identified in 17 of the 24 (70.8%) patients by lymphoscintigraphy, in 21 of 24 (87.5%) patients by in vivo probing and in 23 of 24 (95.8%) patients by ex vivo probing. On an individual basis the numbers of hot nodes identified by lymphoscintigraphy and in vivo probing were low (40% and 36%, respectively) compared to the high detection rate for ex vivo probing (91%). CONCLUSIONS: Although sentinel lymph nodes can be used for prostate cancer, detailed lymph node mapping and extended dissection backup are currently needed. It is also important to establish novel procedures for accurate and complete removal of all hot nodes.

Aged↗

PubMed1992

Involvement of the oxidative burst in phytoalexin accumulation and the hypersensitive reaction.

The role of the oxidative burst, transient production of activated oxygen species such as H(2)O(2) and superoxide (O(2) (-)) in elicitation of phytoalexins and the hypersensitive reaction (HR) was investigated in white clover (Trifolium repens L.) and tobacco (Nicotiana tabacum L.). H(2)O(2) and O(2) (-) production was measured as chemiluminescence (CL) mediated by luminol, which was added to suspension-cultured white clover just before measurement in an out-of-coincidence mode scintillation counter. Maximum CL occurred between 10 and 20 min after addition of 0.4 x 10(8) colony-forming units/mL of incompatible Pseudomonas corrugata or 158 mum HgCl(2). Autoclaved P. corrugata produced a slightly higher response. Elicitation of cells with 25 mum HgCl(2) did not produce CL. Preincubation of plant cells in superoxide dismutase, which converts O(2) (-) to H(2)O(2), for 2 min before addition of bacteria did not significantly increase maximum CL levels (P >/= 0.05). Preincubation of plant cells with catalase for 2 min before addition of bacteria prevented the increase in CL, confirming that H(2)O(2) is the substrate for the luminol reaction. Addition of live bacteria or HgCl(2) (25 and 158 mum) to white clover increased levels of the phytoalexin medicarpin during a 24-h period, but addition of autoclaved bacteria did not elicit formation of medicarpin. Preincubation of plant cells with catalase, which quenched the bacteria-induced oxidative burst, did not decrease phytoalexin accumulation. Live bacteria infiltrated into Havana 44 tobacco leaf panels induced development of the HR, but autoclaved bacteria did not. Incubation of live bacteria with superoxide dismutase and catalase before infiltration into tobacco leaves did not interfere with development of the HR. Tobacco leaf panels infiltrated with up to 158 mum HgCl(2) did not develop an HR. These results suggest that an oxidative burst consisting of H(2)O(2) and O(2) (-) does occur during these two plant defense responses, but it may not be a necessary element of the signaling system for HR and phytoalexin formation.

Journal Article↗

PubMed1999

Electron density study of KNiF3 by the vacuum-camera-imaging plate method.

The electron density measurements of KNiF(3), nickel potassium trifluoride, by the vacuum-camera-imaging plate (VCIP) method and using a four-circle diffractometer with scintillation counter, are performed and compared. In the IP (imaging plate) case evacuation allowed the background around peaks to be reduced 50 times, which significantly increased the accuracy of the data, especially for high-angle reflections. A new VIIPP program for visualizing and integration of IP data was designed to treat the data, in which the correction for oblique incidence was applied. The resulting electron density reproduces all the features of the accurate conventional measurement.

Journal Article↗

PubMed1995

Comparison of different X-ray data-collection systems using the crystal structure of octreotide.

The octapeptide octreotide crystallizes with three peptide molecules and about 20% water in the asymmetric unit, and in many ways possesses diffraction properties similar to those of a 'mini-protein' consisting of 24 amino-acid residues. It diffracts to about 1.0 A but data in the range 1.4-1.0 A are weak. It provides a suitable test of different macromolecular X-ray data-collection techniques, especially of their ability to measure weak reflections accurately. In contrast to typical proteins it is possible to perform a full anisotropic refinement, that we believe provides a more objective test of the quality of the data than the internal consistency of equivalent reflections. We have collected a total of six data sets. The X-ray sources included synchrotron radiation, Cu Kalpha rotating anodes and Mo Kalpha sealed tubes; position-sensitive two-dimensional detectors from four manufacturers and a four-circle diffractometer with scintillation counter were employed. Two of the six data sets were collected at low temperature. Reasonable anisotropic refinement was possible with all area-detector data sets, although significant differences in the precision of the final model were observed. In addition we tested the ability of automated Patterson interpretation to solve the structure using the six independent data sets. The structure solution was only successful using the synchrotron or rotating-anode data sets, i.e. for the more intense sources. It appears that for structure solution the maximum resolution of the data is critical, whereas for refinement the accuracy of the data is more important.

Journal Article↗

PubMed1996

A new powder diffractometer for synchrotron radiation with a multiple-detector system.

A new powder diffractometer for synchrotron radiation with six detector arms has been constructed. Five detector arms are attached radially at intervals of 25 degrees to the 2theta axis and form a multiple-detector system. Five scintillation counters coupled with flat Ge(111) crystal analyzers on the respective arms can simultaneously record the whole powder pattern divided into five segments, each with an equal 2theta span. The optics design is based on flat-specimen reflection geometry using a parallel beam. The intensity data are collected using a 2theta step-scan technique in asymmetric diffraction at a fixed incident angle. A sixth multi-purpose detector arm can be used in the conventional single-arm scan mode. It can be equipped with various kinds of analyzers such as long horizontal parallel slits, a fiat or channel-cut crystal analyzer, a receiving slit and a solid-state detector. Test operations of the multiple-detector system, conducted at the Photon Factory in Tsukuba, recorded a full width at half maximum of 0.022 degrees and a peak maximum intensity of more than 40000 counts s(-1) for the (111) reflection from Si powder. The whole powder pattern of Mg(2)SiO(4) over a 2theta range of 130 degrees could be step-scanned at a step interval of 0.004 degrees (2theta) in just 4 h. Results of whole-powder-pattern decomposition and Rietveld refinement of the Mg(2)SiO(4) pattern are given.

Journal Article↗

PubMed1998

A bent Laue analyser crystal for Rayleigh-to-Compton computed tomography.

A new optical system to perform tomography based on the Rayleigh-to-Compton (RC) method with high spatial and spectral resolution is presented. The RC technique allows the effective atomic number of a sample to be measured and finds application in bone mineral densitometry in medicine. It is particularly useful for the characterization of the distribution of biological materials which do not exhibit distinctive diffraction peaks. The system is based on the separation of the elastic line from the spectrum that is scattered by the sample by means of a bent Laue analyser crystal, and the subsequent independent detection of the elastic and inelastic parts of the spectrum with two large-area scintillation counters. The high energy resolution permits operation at low momentum transfer, where the RC method has its best contrast-to-noise ratio for low-Z materials. The geometrical and spectral requirements in terms of the incident beam and the conical analyser crystal are discussed. A first-generation tomographic imaging system (pencil beam, scanned sample) as implemented at the ESRF Compton-Scattering Station ID15B is described. A high-resolution tomographic reconstruction of a bone sample is presented.

Journal Article↗