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PubMed1993

A scintillation spectrometer for direct comparison of neutron energy spectra at high and low rates.

The energy spectrum of the HB11 beam at HFR, Petten, has previously been measured by proton and alpha recoil in hydrogen and helium gas proportional counters at power levels of a few kW. There is some doubt whether the spectrum remains the same at the much higher power of 45 MW required for therapeutic fluxes. In order to test this point, a scintillation detector has been developed at the Paul Scherrer Institute, Villingen, Switzerland. While the device is again based on the proton recoil reaction, a combination of mm-sized plastic scintillators and fast electronics will allow it to operate at both a few kW and 45 MW, permitting direct comparison of energy spectra at these very different power levels. Results of preliminary tests at LFR, Petten, are presented.

Humans↗
PubMed1980

A cytotoxicity assay using 3H-uridine and emulsions scintillator.

In immunological studies, cytotoxicity assay are extremely important. The assay method was modified so that the radioactivity of beta-decaying isotopes in a large volume of aqueous sample could be counted. Through tests of various scintillators, it was found that emulsion scintillators had a higher counting efficiency than toluene- or dioxane-based scintillators. The results obtained by this method using an emulsion scintillator agreed well with those obtained by the 51Cr release method. The advantages of the emulsion scintillator method are as follows: (a) the activity of a beta-decaying isotope can be counted in a large volume of aqueous sample, (b) a long half-life beta-decaying isotope can be used, (c) the effects of free labeled materials can be eliminated by simple procedures, and (d) no gamma counter is needed.

Animals↗
PubMed1977

Whole-body retention of radioxenon.

The total-body retention of 127Xe, and its variation with time following short, nonequilibrium periods of inhalation, were measured in vivo so as to refine dosimetry calculations. Radioactivity in the chest region and in the recirculating xenon-air mixture was measured continuously during re-breathing of the gas mixture and in the first 5 min of the immediate gas-washout period using a scintillation camera and shielded NaI detector, respectively. Subjects were then counted in a whole-body counter at varying time intervals until background levels were reached, usually in 72 hr. Five components of Xe clearance from the entire body were measured; they had biologic half-times of 21.7+/-12.4 sec, 3.05+/-1.72 min, 0.04+/-0.11 hr, and 2.71+/-0.87 hr, and a long-term component varied between 7.59 and 17.04 hr. The half-time of the last component correlated highly with the percent of total-body fat. After 10-min inhalations of the xenon-air mixture, approximately one-third of the total xenon was transferred to the body tissues, extrapolated back to the start of gas washout. Of this amount, 13% was associated with the slowest component of clearance.

Adipose Tissue↗
PubMed2004

Self-cleaning in an estuarine area formerly affected by 226Ra anthropogenic enhancements.

The estuary of the Odiel River has been affected by both direct discharges of phosphogypsum (radium enriched industrial waste) and dissolution and weathering of the exposed piles where this radium enriched waste was stored. In 1998 the waste management policy for industries changed. The direct discharges stopped and the new phosphogypsum piles were well protected against dissolution processes, avoiding any transference of radium into the environment. This work presents a study of the evolution with time (1999-2002) of the levels of 226Ra in river water and sediment samples with the new waste management policy. A liquid scintillation technique was used to measure the 226Ra activity concentration in sediment samples. A gas-proportional counter was also used to measure the 226Ra activity concentration in river water samples. The main conclusion is that a systematic and continuous decrease of the activity concentration of 226Ra with time in the Odiel River estuary is occurring. Thus, a possible self-cleaning in the estuary, once the direct waste discharges were avoided, can be inferred.

Journal Article↗
PubMed2004

Local vascular access of radioprotein injected subcutaneously in healthy subjects and patients with breast cancer-related lymphedema.

UNLABELLED: The aim of the study was to use dual-isotope lymphoscintigraphy in healthy volunteers and women with breast cancer-related lymphedema (BCRL) to detect and quantify transport of radiolabeled protein from a subcutaneous injection depot to local blood vessels as a potential mechanism of protection against edema resulting from treatment to the axilla. METHODS: A total of 29 subjects and 18 women with a history of BCRL received bilateral subcutaneous injections of human IgG (HIgG) in the second dorsal web space of each hand, (99m)Tc-HIgG on one side and (111)In-HIgG on the other. In 8 further healthy subjects, epinephrine was administered with the labeled HIgG. Radioactivity at each depot was measured at regular intervals for a total of 3 h using a collimated sodium iodide scintillation detector, and radioactivity in venous blood sampled from both arms was measured using an automatic sample counter. Ipsilateral blood time-concentration curves were corrected for recirculating activity by subtraction of the simultaneous contralateral concentration, to define the component of ipsilateral blood resulting from local vascular access of radioprotein. Accumulation of activity in blood was expressed in relation to injected activity and activity that had left the depot and was calculated as a function of time-in systemic blood, by multiplying contralateral concentrations by an estimate of the subject's blood volume, and in ipsilateral blood, by using indicator dilution theory and an assumed forearm blood flow of 20 mL/min. RESULTS: (99m)Tc-HIgG and (111)In-HIgG behave almost identically with respect to depot clearance and accumulation in contralateral venous blood, with or without epinephrine, which reduced both depot clearance and blood accumulation rate. Moreover, a side-to-side correlation with respect to contralateral accumulation was present in healthy subjects, was not abolished by epinephrine, and was maintained in the face of asymmetric accumulation in BCRL. Contralateral accumulation of radioprotein was reduced in BCRL after injection into the affected side only when the hand was involved. In contrast to contralateral sampling, ipsilateral time-concentration and accumulation profiles were consistent with instability of (111)In-HIgG and rapid local vascular access of small amounts of protein-free (111)In. Experiments based on precipitation of protein with trichloroacetic acid confirmed relatively high levels of unbound ipsilateral (111)In, especially in samples obtained early after injection. Substantial accumulation of protein-bound (99m)Tc was observed in ipsilateral blood, with a time course similar to that of contralateral accumulation. Positive correlation between ipsilateral and contralateral blood (99m)Tc activity was observed at all time points, often significantly, in contrast to (111)In, for which it was negative at all time points. Ipsilateral accumulation of (99m)Tc adjusted for activity that had left the depot was unchanged with respect to the affected arm in BCRL patients. CONCLUSION: Whereas (111)In-HIgG and (99m)Tc-HigG are interchangeable for measurement of depot clearance and contralateral venous accumulation rates, ipsilateral sampling is much more sensitive to protein-free radionuclide and detects significant differences resulting from some instability of (111)In-HIgG. On the basis of (99m)Tc data, there appears to be substantial local vascular access of radioprotein within the arm, both in healthy subjects and in patients with BCRL, through either lymphaticovenous communications or direct transendothelial transport.

Arm↗
PubMed2000

Standardisation of 204Tl at IRMM

IRMM participated in a recent international comparison for the standardisation of a 204Tl solution organised by BIPM. The activity concentration of the 204Tl solution was measured at IRMM using 3 independent methods; Liquid Scintillation Counting using the CIEMAT/NIST method, 4pi-CsI counting and 4pibeta counting using a large pressurised proportional counter. This article describes the measurements in detail and discusses potential problems in the standardisation of 204Tl.

Journal Article↗
PubMed1974

Rapid method for the radioisotopic analysis of gaseous end products of anaerobic metabolism.

A gas chromatographic procedure for the simultaneous analysis of (14)C-labeled and unlabeled metabolic gases from microbial methanogenic systems is described. H(2), CH(4), and CO(2) were separated within 2.5 min on a Carbosieve B column and were detected by thermal conductivity. Detector effluents were channeled into a gas proportional counter for measurement of radioactivity. This method was more rapid, sensitive, and convenient than gas chromatography-liquid scintillation techniques. The gas chromatography-gas proportional counting procedure was used to characterize the microbial decomposition of organic matter in anaerobic lake sediments and to monitor (14)CH(4) formation from H(2) and (14)CO(2) by Methanosarcina barkeri.

Anaerobiosis↗
PubMed2002

Quantification of lymphatic function for investigation of lymphedema: depot clearance and rate of appearance of soluble macromolecules in blood.

UNLABELLED: The object of this study was to develop a new technique for the quantitative measurement of lymphatic function. The rate of clearance of radiolabeled protein from a subcutaneous depot is supplemented by measurement of the appearance of the protein in venous blood. This initial study was performed on normal arms, with a view to subsequent clinical application such as in the investigation of women with breast cancer--related lymphedema (BCRL). METHODS: Fourteen healthy volunteers (12 women, 2 men) and 8 women awaiting surgery for breast cancer were recruited for the study. Each received subcutaneous depot injection of protein solution in the second dorsal web space of each hand, labeled with (111)In on one side and with (99m)Tc on the other side. Human serum albumin (HSA) was the protein used in the first 8 subjects and human polyclonal immunoglobulin G (HIgG) was used thereafter. The activity at each depot was measured at regular intervals using a collimated sodium iodide scintillation detector, and the activity in venous blood sampled from both arms was measured in an automatic sample counter. RESULTS: (99m)Tc-HSA cleared from the depot consistently faster than (111)In-HSA (P = 0.001). The proportions of radionuclide remaining bound to protein in venous blood were higher for (99m)Tc than for (111)In. HIgG displayed improved labeling stability for both nuclides, reflected in equal rates of clearance. Blood activity rose steadily after an early latent phase and for HIgG correlated strongly with the rate of clearance from the depot (P < 0.001). Marked variation between individuals was observed. CONCLUSION: A dual-isotope technique relies on identical behavior of the 2 radiopharmaceuticals used. This study shows that this is the case with respect to HIgG but not HSA. (99m)Tc-HSA cleared faster than (111)In-HSA and yet displayed better in vivo labeling stability. We conclude that (111)In dissociates from HSA in the depot but then becomes locally bound. Using HIgG, a close correlation was observed between the rates of clearance from the depot and the appearance in venous blood. This finding suggests that HIgG would be a suitable marker for subsequent dual-isotope studies on women with BCRL.

Adult↗
PubMedDate not supplied

Detection of radioactivity on microtiterplates in situ using a photon-counting imager.

A position-sensitive single-photon counting imaging system, which can determine intensity and location of a light source, has been used for the detection of 125I-labeled Interleukin-1 and [3H]thymidine in 96 wells of a microtiter plate (MTP) simultaneously. 4 Bq (1 Bq = 1 Bequerel = 1 disintegration/s), 22 and 150 Bq of 125I and 3, 10 and 100 Bq of 3H were visualized and quantified by transforming the radioactivity into light in the visible range by means of Xtalscint, a solid scintillator. After only 1 min of photon accumulation time, the highest radioactivity of both isotopes could be clearly distinguished from background. Photon counts correlate well with radioactivity measured in a beta-counter (for 3H) and a gamma-counter (for 125I). The overall counting efficiency was about 5% for 125I and 3% for 3H.

Animals↗
PubMed1977

[Estimation of individual renal function by Tc-DMSA-uptake (author's transl)].

Hg-Cl2-accumulation and early hippuran uptake are widely used for the estimation of individual renal function, a clinically important procedure in nephrological-urological nuclear medicine. After clinical experience in more than 2500 patients we investigated the assessment of individual renal function by the uptake of Tc-DMSA, a new radiopharmaceutical for renal scintigraphy. Tc-DMSA-uptake was measured after application of 0.8-1.6 mCi Tc-99m-DMSA by a scintillation camera connected to a computer system and by a rectilinear scanner with data storage, additionally hippuran kinetics were registered with a scintillation camera, the total body clearance was performed due to the method of Oberhausen with a modified whole body counter. A good agreement and high correlation between Tc-DMSA-uptake with background corection and the unilateral renal clearance could be established. This easily available and clinically valuable method also can be adjusted to institutions with a rather simple equipment.

Evaluation Studies as Topic↗
PubMed1979

[Experimental investigation with 198Au colloid as to lymph communications between the retrobulbar space and the thyroid gland (author's transl)].

The problem of a direct connection of lymph drainage between the retrobulbar space and the thyroid gland was examined using the lymphotropic radioactive tracer 198Au colloid. Twelve rabbits were examined. Six animals were injected with 50 muCi 198Au colloid into the right thyroid lobe and six animals into the right retrobulbar space. Distribution and total body radioactivity was measured in vivo using a scintillation camera with a computer. After 6 hrs tissue specimens of different organs were measured in a well-counter. The discharge of activity from the thyroid after 6 hrs was significantly higher than that from the retrobulbar space (63% versus 33.5%). This was probably due to a higher vascularisation and to a higher degree of lymph drainage of the thyroid. The lymph drainage of the thyroid gland as well as of the retrobulbar space occurred mainly via the lymphonodi cerv. proff. No significant activity was found in the retrobulbar space after thyroid injection or in the thyroid after retrobulbar injection. It may be concluded from these results that there are no direct lymph connections between the retrobulbar space and the thyroid gland. However, indirect communications via the deep cervical lymph nodes cannot be excluded in the event of reverse lymph flow.

Animals↗
PubMed2003

Stomach-specific anti-H. pylori therapy. II. Gastric residence studies of tetracycline-loaded chitosan microspheres in gerbils.

This study examines the gastric residence of chitosan microspheres and the local tetracycline concentrations following oral administration in gerbils. Chitosan microspheres were prepared by ionic cross-linking and precipitation with sodium sulfate. Gastric retention studies were performed by administering radioiodinated [125I] chitosan microsphere suspension in the nonacid-suppressed and acid-suppressed states. At different time points, animals were sacrificed, and the radioactivity in tissues and fluids was measured with a gamma counter. Local tetracycline concentrations were measured using chitosan microspheres loaded with tritiated-[3H]-tetracycline. The radioactivity, measured with a liquid scintillation analyzer, was used to determine the microg of drug per gram of tissues or fluids under nonacid-suppressed and acid-suppressed states. Microspheres with a spherical shape and an average diameter of 2.0-3.0 microm were formed. After 2 hr in the fasted stomach, approximately 10% of the administered dose remained. The microspheres were predominantly found in the colon after 6 hr of administration. There was no detectable radioactivity in the small intestine, plasma, urine, liver, and kidneys. Additionally, acid suppression with ranitidine did not influence the gastric residence time of chitosan microspheres. To our disappointment, tetracycline concentration profile in the stomach from microsphere formulation was similar to the aqueous solution. Also, there was no significant difference between the stomach tetracycline concentrations in the nonacid-suppressed and acid-suppressed states. The drug was predominantly found in the colon and urine samples after 6 hr. Tetracycline could not be detected in the plasma, small intestine, liver, or kidneys. Results of this study show that chitosan microspheres prepared by ionic cross-linking do not provide a longer residence time in the fasted gerbil stomach. The tetracycline concentration profile in the stomach, following administration in microsphere formulation, was similar to that of aqueous solution. Lastly, acid suppression did not influence the gastric residence time of chitosan microspheres or tetracycline concentration profiles.

Animals↗