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PubMed1983

1976 Hanford americium exposure incident: in vivo measurements.

Detailed external measurements were made of internally deposited 241Am in a nuclear chemical operator involved in an americium exposure accident at the Hanford plant. Despite some interference from high-level external contamination, quantitative measurements of the 241Am content in the lung, liver and bones were made starting on the third day after the accident. The rate of excretion of 241Am from these organs was determined. The 241Am embedded in the skin of the face and head was carefully mapped. The distribution over the total length of the body was also determined. Linear and rectilinear scanners, gamma cameras, large and small scintillation detectors, proportional counters, and Si(Li) and intrinsic germanium detectors were used to evaluate the internal deposition. Methods of calibration for quantitative measurement included simulation of the 241Am activity in both phantom and cadaver parts.

Absorption↗
PubMed1975

A longitudinal study of total body potassium in normal children.

Most investigators studying changes in body composition during growth agree to the desirability of having longitudinal data. A group of 110 boys and 126 girls, studied annually for 4-5 years with 880 measurements of total body K in a 2pi liquid scintillation whole body counter, had total body K vs. height and total body K vs. weight data that fit previously described regression lines.

Adolescent↗
PubMed1990

[The use of the direct basophil degranulation test for the diagnosis of allergy].

Basophil degranulation test (BDT) was used in examinations of patients suffering from allergies. A modified technique was employed with toluidine blue staining and basophil scintillation in a counter chamber. The examinees were divided into three groups. Group 1 (n = 34) consisted of patients suffering from atopic bronchial asthma with suspected sensitization to home dust. Group 2 included 118 patients with a history of allergy to penicillin. Group 3 consisted of 51 patients with drug allergies (streptomycin, vitamin B1, procaine, analgin intolerance). In all the cases specific diagnosis was confirmed by skin and provocation test. 71.4 percent of the patients with sensitization to home dust allergen showed positive results in BDT, as did 68.6 percent of Group 3 subjects. Of the cases with penicillin sensitization confirmed by application test 91.7 percent were positive in BDT, of those with positive intradermal tests, 66.7 percent were BDT-positive, this being probably explained by individual sensitivity of the patients. These results recommend BDT, an informative and simple technique, for wide practice.

Asthma↗
PubMed1989

[Effect on erythropoietin production after inhibition of RNA synthesis by D-actinomycin and hyperglycemia].

Short-lasting hypobaric hypoxia was used in male white rats as a stimulus of erythropoietin synthesis (0.42 atm.). Plasma erythropoietin activity was determined by a biologic method on highly sensitive to exogenous erythropoietin recipients-posthypoxic polycytemic mice. Erythropoietin activity was estimated by measuring the percentage of incorporated 59Fe in newly formed erythrocytes of mice under the influence of the examined plasma, using automatic scintillation gamma-counter. Hypoxia induced an increase of plasma erythropoietin activity with 54% in comparison with control animals. Administration of actinomycin D in a dose of 0.4 microgram/g of body mass before exposure of the animals to hypoxia diminished production of erythropoietin with 58% in comparison with that of rats, exposed to pure hypoxia. A suggestion could be made that the formation of erythropoietin requires DNA dependent RNA-synthesis.

Animals↗
PubMed1989

Plasma erythropoietin activity in diabetes patients, studied by determining the 59Fe incorporation in posthypoxic polycythemic mice.

The plasma erythropoietin activity in diabetes patients was studied using methods for biological testing on posthypoxic polycythemic mice, based on the incorporation of 59Fe in the newly-formed red blood cells of the animals. The data are read on an automatic scintillation gamma-counter. Considerably higher erythropoietin activity of the plasma obtained from diabetics (p less than 0.01) compared with clinically health individuals has been obtained, as well as a statistically significant difference in the percentage of 59F incorporated in the newly-formed erythrocytes of the animals treated with that plasma, compared with the animals treated with saline. A dependence has been found between the chronic hyperglycaemia and the plasma erythropoietin level.

Animals↗
PubMedDate not supplied

Measurement of dose distributions of linear energy transfer in matter irradiated by fast neutrons.

A detector has been developed and used to measure dose distributions versus linear energy transfer to thin gas targets in spherical geometry from fast neutron irradiation of tissue-equivalent plastic and carbon. The detector is a hemispherical proportional counter with a Cs(T1) scintillator at the center of the hemisphere. The coincidence of the proportional counter signals constrain the measurements to charged particles traversing the radius of the hemisphere. The charged particle energy deposition distributions are directly measured for a known pathlength. The A-150 kerma factor was measured at a neutron energy of 14.8 MeV and is in agreement with tabulated values. The carbon kerma factor measurements are less than the tabulated value at 14.8 MeV. The alpha-particle production in carbon was measured for neutron energies from 14.1 to 14.8 MeV and is compared with existing data.

Energy Transfer↗
PubMedDate not supplied

Radiation detectors in nuclear medicine.

Single-photon-emitting or positron-emitting radionuclides employed in nuclear medicine are detected by using sophisticated imaging devices, whereas simpler detection devices are used to quantify activity for the following applications: measuring doses of radiopharmaceuticals, performing radiotracer bioassays, and monitoring and controlling radiation risk in the clinical environment. Detectors are categorized in terms of function, the physical state of the transducer, or the mode of operation. The performance of a detector is described by the parameters efficiency, energy resolution and discrimination, and dead time. A detector may be used to detect single events (pulse mode) or to measure the rate of energy deposition (current mode). Some detectors are operated as simple counting systems by using a single-channel pulse height analyzer to discriminate against background or other extraneous events. Other detectors are operated as spectrometers and use a multichannel analyzer to form an energy spectrum. The types of detectors encountered in nuclear medicine are gas-filled detectors, scintillation detectors, and semiconductor detectors. The ionization detector, Geiger-Müller detector, extremity and area monitor, dose calibrator, well counter, thyroid uptake probe, Anger scintillation camera, positron emission tomographic scanner, solid-state personnel dosimeter, and intraoperative probe are examples of detectors used in clinical nuclear medicine practice.

Health Physics↗
PubMed2003

Determination of potassium in the skeletal muscles by whole-body counting.

Changes in muscular function are related to nutritional status, disease and physical activity. To study these relationships, it is desirable to be able to determine the whole body potassium content, which is characteristic to the muscular tissue. This can be achieved by measurements in a whole-body counter, identifying contributions from the upper and lower parts of the body. In a whole-body counter with large plastic scintillators, a special measuring methodology is required. Such a method of measuring (40)K in the leg muscles, extracting the part of the detector signal originating from the lower part of the body, has been developed and tested by independent phantom measurements. The results suggest that it is suited to perform regional measurements of body potassium but validation and implementation into clinical research are still necessary.

Humans↗
PubMedDate not supplied

The absolute standardization of 32P and 204Tl at LNMRI.

32P and 204Tl solutions were standardized within the frame of the international key comparisons organized by bureau international des poids et mesures, in 2002. The activity concentration of 32P was measured by counting solid sources in a 4pibeta proportional gas flow counter and by liquid scintillation counting. The self-absorption in solid sources for 4pibeta counting and the presence of 33P as an impurity were evaluated. The combined standard uncertainty for 32P was 0.59% in the 4pibeta counting and 0.38% in the liquid scintillation counting. Liquid scintillation counting was used to measure the activity concentration of 204Tl with combined standard uncertainty of 0.35%.

Brazil↗
PubMed1987

Total body potassium measurement--the effect of fallout from Chernobyl.

As a result of fallout from the nuclear accident at Chernobyl in April 1986, the caesium radioisotopes, 134Cs and 137Cs, have been detected in man. A minor consequence of this is that total body potassium (TBK) measurements obtained from the whole body activity of 40K, a naturally occurring radioisotope of potassium, can be overestimated because of gamma spectrum overlap between 134Cs and 40K. Whole-body activities for 134Cs and 40K were measured in 18 healthy adults (13 M, 5 F) in June/July, 1986, using a whole-body counter with NaI crystal scintillation detectors. Studies using anthropometric phantoms containing known activities of the two radionuclides, allowed the contribution of 134Cs to the '40K activity' in the human subjects to be assessed. The group mean 134Cs level was 172 Bq, resulting in an average overestimate in TBK of 2.8%. It is recommended that when TBK measurements are being undertaken and 134Cs contamination is suspected, then 134Cs levels should be measured and their effect corrected for.

Accidents↗
PubMed2004

Measurement and Monte Carlo modelling of the JRC 241Am-Li(alpha,n) source spectrum.

The neutron energy spectrum of the JRC 241Am-Li(alpha,n) radionuclide source has been measured at the PTB in Germany using various spectrometry systems, such as Bonner spheres, proton recoil counters and NE213 liquid scintillators. The source photon spectrum has been measured and the neutron contamination due to traces of beryllium through the 9Be(alpha,n)12C reaction has been determined. The effects associated with source encapsulation and the materials it contains have been investigated previously, using Monte Carlo simulations, the various structures seen in the spectra have been explained and the anisotropy of fluence distributions in 4pi have been calculated and compared to measurements. These extensive high resolution spectrometry measurements have been coupled to Monte Carlo calculations to provide a realistic spectrum and new spectrum-averaged fluence-to-dose equivalent conversion coefficients for the actual 241Am-Li source.

Americium↗
PubMed2004

Reference dosimetry measurements for the international intercomparison of criticality accident dosimetry SILENE 9-21 June 2002.

An international intercomparison of criticality accident dosimetry systems took place in the SILENE reactor, in June 2002. Participants from 60 laboratories irradiated their dosemeters (physical and biological) using two different configurations of the reactor. In preparation for this intercomparison, the leakage radiation fields were characterised by spectrometry and dosimetry measurements using the ROSPEC spectrometer associated with a NE-213 scintillator, ionisation chambers, GM counters, diodes and thermoluminescence dosemeters (TLDs). For this intercomparison, a large area was required to irradiate the dosemeters both in free air and on phantoms. Therefore, measurements of the uniformity of the field were performed with activation detectors and TLDs for neutron and gammas, respectively. This paper describes the procedures used and the results obtained.

Equipment Design↗
PubMed2003

Influence of fragment reaction of relativistic heavy charged particles on heavy-ion radiotherapy.

The production of projectile fragments is one of the most important, but not yet perfectly understood, problems to be considered when planning for the utilization of high-energy heavy charged particles for radiotherapy. This paper reports our investigation of the fragments' fluence and linear energy transfer (LET) spectra produced from various incident ions using an experimental approach to reveal these physical qualities of the beams. Polymethyl methacrylate, as a substitute for the human body, was used as a target. A deltaE-E counter telescope with a plastic scintillator and a BGO scintillator made it possible to identify the species of fragments based on differences of various elements. By combining a gas-flow proportional counter with a counter telescope system, LET spectra as well as fluence spectra of the fragments were derived for each element down from the primary particles to hydrogen. Among them, the information on hydrogen and helium fragments was derived for the first time. The result revealed that the number of light fragments, such as hydrogen and helium, became larger than the number of primaries in the vicinity of the range end. However, the greater part of the dose delivered to a cell was still governed by the primaries. The calculated result of a simulation used for heavy-ion radiotherapy indicated room for improving the reaction model.

Ions↗
PubMed1976

A simple method for the differential measurement of 125I and 3H by liquid-scintillatin spectrometry.

1. A method is described for the differential radioactivity counting of 125I and 3H in a liquid-scintillation spectrometer without a separate gamma counter. 2. The sample was contained in a polyethylene miniature vial placed centrally in a standard 20 ml glass scintillation vial containing a tin-loaded scintillant. 3. A direct measure of the 125I radioactivity at an efficiency of 30% was then obtained by radioactivity counting in the pre-set 3H window of a scintillation spectrometer. No counts for 3H radioactivity were registered at this stage because of the barrier to the passage of the low-energy beta-particles provided by the wall of the polyethylene vial. 4. After mixing the sample and scintillant both 125I and 3H were detected at efficiencies of 73% and 29% respectively. Subtraction of the 125I contribution from the combined radioactivity count rate then gave the net 3H count.

Humans↗
PubMed2004

Response of a lithium gadolinium borate scintillator in monoenergetic neutron fields.

Accurate estimation of neutron dose requires knowledge of the neutron energy distribution in the working environment. Existing neutron spectrometry systems, Bonner spheres for example, are large and bulky, and require long data acquisition times. A portable system that could indicate the approximate neutron energy spectrum in a short time would be extremely useful in radiation protection. A composite scintillator, consisting of lithium gadolinium borate crystals in a plastic scintillator matrix, produced by Photogenics is being tested for this purpose. A prototype device based on this scintillator and digital pulse processing electronics has been calibrated using quasi-monoenergetic neutron fields at the low-scatter facility of the UK National Physical Laboratory (NPL). Energies selected were 144, 250, 565, 1400, 2500 and 5000 keV, with correction for scattered neutrons being made using the shadow cone technique. Measurements were also made in the NPL thermal neutron field. Pulse distributions collected with the digitiser in capture-gated mode are presented, and detection efficiency and energy resolution derived. For comparison, neutron spectra were also collected using the commercially available Microspec N-Probe from Bubble Technology Industries, which consists of an NE213 scintillator and a 3He proportional counter.

Algorithms↗
PubMed1993

Criteria of applicability for autoradiography of tritium.

Autoradiography is an effective tool for the imaging of radionuclide distributions in various samples. In sophisticated applications with special preparation and development of sample-emulsion combinations and subsequent grain counts it can be highly quantitative, but it requires carefully controlled conditions and a variety of counter-checks, for example through scintillation spectroscopy. Less refined applications use X-ray films as detectors, and their seeming simplicity tends to invite artefacts and misinterpretations. Particular care needs to be taken, if one deals, or presumes to deal, with the low-energy beta-emitter tritium. Because of the short electron ranges the film must be in intimate contact with the sample, which tends to produce chemographic artefacts; without added spectroscopic measurements it is impossible to discriminate the spurious signals from a blackening of the film due to tritium. Recent statements concerning autoradiographic tritium measurements in tree samples have created considerable public concern and have demonstrated the pitfalls of uncritical use. This paper presents order-of-magnitude criteria for the detection threshold in the autoradiography of tritium; they can serve as an exclusion principle for some of the more extravagant misinterpretations.

Autoradiography↗
PubMed1985

Phenotyping of proliferating cells in cultures of human lymphocytes.

Lymphocytes stimulated with mitogens, alloantigens or soluble antigens were pulsed with tritiated thymidine to label proliferating cells. Aliquots of the cells were labeled with OKT 4 or OKT 8 mouse monoclonal antibodies and then incubated in microtiter wells coated with goat anti-mouse immunoglobulin G (IgG). Unattached cells were flushed out of the wells: individual wells were then separated for counting in scintillation fluid in a B counter. This method permits simple characterization of the relative T cell subset proliferative responses and is clinically applicable.

Antibodies, Monoclonal↗