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At least 145 records · Page 8Linked to original sources
PubMed1987

Model for 82Sr/82Rb generator elution profiles: a secondary approach to radioassay/dosimetry.

Static (dose calibrator) assays of 82Rb bolus yield erroneous estimates of administered activity by ignoring the asymmetric output of 82Sr/82Rb generators. Though on-line monitoring of elution profile improves accuracy for quantitative purposes, it requires an elaborately shielded detector and associated electronics at patient-study site. Our alternative approach based on mathematical description of the dynamic characteristics of the generator accurately predicts elution profiles over a broad range of flow rates.

Humans↗
PubMed1979

Preparation of 52Fe and its use in a 52Fe/52mMn generator.

Clinically useful quantities of 52Fe have been prepared at the Brookhaven Linac Isotope Producer (BLIP) by bombarding manganese or nickel targets with medium energy protons. After chemical separation, 52Fe is loaded onto a generator column from which carrier-free 52Mn is eluted. The 52mMn generator is potentially useful in emission computed tomography.

Iron Radioisotopes↗
PubMed1987

Radioanalysis of 82Rb generator eluates.

The activity of 82Rb produced from a 82Sr/82Rb generator is dependent on elution conditions (volume and eluent flow rate) and sampling conditions (time and position of collection). Assays for 82Rb in generator eluates are described using a commercial dose calibrator in a static procedure and a plastic scintillator in a dynamic procedure. Dynamic assays more accurately reflect the 82Rb administered when the eluate is injected directly. Radionuclidic contaminants which may be present with 82Sr are identified and procedures for their measurement are described.

Humans↗
PubMed1991

Direct radiolabeling of monoclonal antibodies with generator-produced rhenium-188 for radioimmunotherapy: labeling and animal biodistribution studies.

The use of 188Re from an alumina-based 188W/188Re generator has been investigated for antibody radiolabeling. It was found that, with simple labeling techniques, 188Re can be used immediately after elution. The direct radiolabeling of intact antibodies with 188Re is described. Lyophilized antibody preparations have been reconstituted with 188Re taken directly from the generator at specific activities of up to 15 mCi of 188Re per mg of antibody. Radiolabeling yields of 90 to 98% have been obtained, with the incorporation rate being dependent upon time and the relative concentrations of the reagents. It was determined that the conjugates were immunoreactive and stable when challenged by serum in vitro, with 188Re-immunoglobulin G showing adequate resistance to reoxidation with no transfer of 188Re to serum protein. 188Re-antibody conjugates were shown to clear from the blood faster than the corresponding 131I-labeled antibody, giving rise to good tumor/nontumor ratios at 24 to 72 h postinjection, while serum samples taken from the animals have shown that the circulating 188Re remained bound to immunoglobulin G. The combination of the technologies of the 188W/188Re generator, the direct labeling methodology, and the use of single-vial lyophilized antibody makes the use of 188Re-radiolabeled monoclonal antibodies a simple and convenient method of cancer radioimmunotherapy with a beta-emitting radionuclide.

Animals↗
PubMed1992

An assessment of factors which influence the effectiveness of the modified in vivo technetium-99m-erythrocyte labeling technique in clinical use.

This study assessed factors which may contribute to suboptimal image quality when the modified in vivo erythrocyte labeling technique is used with standard clinical 99mTc activities. For each assessment duplicate or triplicate blood specimens were withdrawn from > or = 10 patients, into syringes containing 700-900 MBq 99mTc as pertechnetate. After incubation the percent of 99mTc which was not bound to erythrocytes at blood re-injection time (%Unbound 99mTc), was measured and compared when one of four factors was varied. The most significant results, in descending order of measured effect were: [table: see text] Our data suggest that the requirements for optimal erythrocyte labeling with standard clinical 99mTc activities are: (A) Erythrocyte tinning time between 10 and 30 min; (B) blood volume > or = 3 ml; (C) blood incubation time > or = 20 min; and (D) Generator ingrowth time < or = 24 hr.

Adult↗
PubMed1987

In vivo animal demonstration of the effect of vasoactive drugs using 195mAu and gamma camera techniques.

195mAu, an ultrashort-lived (physical half life = 30.5 s) generator-produced radionuclide, has been used in an animal model to study, by gamma camera techniques, the peripheral effects of the vasoactive drugs norepinephrine and sodium nitroprusside systemically administered or epinephrine (intraarterially) injected at various concentrations. According to the results obtained by the analysis of time activity curves generated from areas of interest drawn on the proximal and distal parts of the limbs, the well known hemodynamic changes induced by these drugs, vasoconstriction (resulting in a decrease of the distal activity recorded), or vasodilatation (shortening the time of radioactivity appearance), could be observed. It is concluded that gamma camera techniques using the ultrashort lived radionuclide 195mAu allow the in vivo study of the effects of vasoactive drugs in an animal model and potentially in clinical situations.

Animals↗
PubMed1987

Experience with a 82Sr/82Rb generator for clinical use.

A 82Sr/82Rb generator system is described which is shown to be suitable for continuous intravenous infusion in man. The breakthrough of the 82Sr parent has been closely monitored and remained less than 18.5 Bq mL-1 of infusate. A method using a 0.05% solution of sodium hypochlorite to disinfect the generator resulted in a sterile and pyrogen free eluate. Recommendations are made for the setting up of the generator to ensure the maintenance of its pharmaceutical integrity.

Humans↗
PubMed1991

110Sn/110In--a new generator system for positron emission tomography.

A generator system, 110Sn/110In, is suggested for use in the labelling of leukocytes with this short-lived (t1/2 = 1.15 h) positron emitting (62%) isotope of indium. The half-life gives the labelled leukocytes time to be adequately distributed but is short enough to allow repeated studies within a few hours. The mother radionuclide 110Sn (t1/2 = 4.15 h) is produced by the reaction natIn(p, xn)110Sn which has a maximum cross-section of 110 mb at approx. 70 MeV and a practical yield of 400 MBq/microAh.

Indium Radioisotopes↗
PubMedDate not supplied

[Technetium-99m production for use in nuclear medicine].

INTRODUCTION: Technetium-99m is the most important radioisotope used in nuclear medicine. Its routine application is ensured by introduction of 99Mo/99mTc generators. This paper reviews the present status and perspectives of different types of generators. Novelties in the production of either 99Mo for generators or directly 99mTc by using accelerators are also included. PRODUCTION OF 99MO IN NUCLEAR REACTORS AND 99MO/99MTC TYPES OF GENERATORS: The main source of 99Mo is a nuclear reactor. Nuclear reaction 99Mo(n, gamma)99Mo is rather simple, but the main disadvantage is a low specific activity of 99Mo. For routine production the nuclear reaction 235U(n,f)99Mo is used. It gives high yields of 99Mo of very high specific activity. However, its main disadvantages are high costs and generation of large quantities of highly radioactive waste. Depending on the separation method several types of generators were developed. The predominant is the chromatographic generator based on fission-produced 99Mo. Due to the disadvantages of (n,f)99Mo production, the alternatives based on (n, gamma)99Mo were developed. However, sublimation (except low temperature sublimation) and extraction generators at the present stage have no perspective. Only gel generators are promising. PRODUCTION OF 99MO AND 99MTC IN ACCELERATORS: Several nuclear reactions are considered. 100Mo(gamma, n)99Mo gives 99Mo of low specific activity. So it could be used in production by sublimation generators. The reaction 100Mo(p,pn)99Mo was also investigated but it seems not to be suitable for routine production of 99Mo. 99mTc can be directly produced by 98Mo(p, gamma)99mTc and 100Mo(p,2n)99mTc nuclear reactions. It seems that the latter could serve as an auxilliary source of 99mTc. CONCLUSION: At present chromatographic generators based on fission-produced 99Mo seem to have no real alternative. Gel and in lesser extent sublimation generators are prosperous, but still not suitable for large scale production of 99mTc. The accelerators offer good possibilities but a real alternative to fission 99Mo has not been found yet.

Molybdenum↗
PubMed1994

[99mTc-generator eluates: effects on the radiochemical purity of the labelling products].

Relatively sensitive kits--which are known for low tin content (HMPAO) or for a complicated chemical labelling procedure (MAG3)--were tested for their efficiency of labelling with eluates of different generators. The radiochemical purity of the labelling products was determined according to the manufacturer's instructions (HMPAO: Amersham Buchler, MAG3: Mallinckrodt Diagnostica) after adding the 99mTcO4- eluates from the different Tc-generators (Amersham Buchler, Mallinckrodt Diagnostica, CIS Biointernational). The radiochemical purity was determined by using radioanalytical methods such as high performance liquid chromatography, thin layer chromatography, paper chromatography and reversed phase chromatography. The quality of the three different generator eluates was sufficient for the labelling of HMPAO and MAG3. The small differences in quality did not limit the use in nuclear medical routine.

Isotope Labeling↗
PubMed1980

A new osmium-191 leads to iridium-191m generator.

A new osmium-191 leads to iridium-191m generator suitable for first-pass radionuclide angiocardiography has been developed. This generator system allows repeated elutions of 4.96-sec iridium-191m from its 15.4-day Os- 191 parent. The Os-191 is loaded on an anion-exchange column (AGMP-1) and Ir- 191m eluted with 0.9% NaCl at pH 1. Each elution (0.6 to 1 ml) of the generator yields about 7 to 10% Ir-191m and gives 0.003-0.008% of Os-191 breakthrough. Toxicity studies of the generator eluate carried out in animals support the safety of using iridium-191m in humans. The long shelf-life of the generator (approximately equal to 2 wk) will allow medical centers to use Ir- 191m for routine clinical diagnosis. Iridium-191m obtained by this method should find additional useful applications in nuclear medicine.

Animals↗
PubMed1989

A new zinc-62/copper-62 generator as a copper-62 source for PET radiopharmaceuticals.

A new 62Zn/62Cu generator system was designed to provide a readily available 62Cu source for positron emission tomographic radiopharmaceuticals, based on the differences of complex formation between Zn and Cu. Noncarrier added 62Cu was selectively eluted as a glycine complex from 62Zn-adsorbed cation-exchange resin (CG-120, Amberlite), when a glycine solution (200 mM) was used as the eluant. The elution efficiency and radionuclidic purity of 62Cu were 70% and greater than 99.9%, respectively. Copper in glycine solution showed rapid complex formation with dithiosemicarbazone, which is one of the established Cu-binding agents for bifunctional chelating radiopharmaceutical.

Chromatography, High Pressure Liquid↗
PubMed1989

Osmium-191/iridium-191m generator based on silica gel impregnated with tridodecylmethylammonium chloride.

A new separation system for an 191Os/191mIr generator is described. The system is composed of two columns in a series: a main column, packed with silica gel impregnated with tridodecylmethylammonium chloride (loaded with high activity 191Os as an osmyl chloride); and a scavenger column, packed with activated charcoal. Iridium-191m is eluted from the generator by pH 1 saline. For clinical use the eluate is buffered by succinate solution before injection. This new system is characterized by high performance (approximately 25% 191mIr recovery with 5 X 10(-4)% 191Os breakthrough) and long shelf-life (3 wk). The buffered eluate is sterile, pyrogen-free, and nontoxic, and contains no 192Ir. It is suitable for first-pass radionuclide angiocardiography with a very low radiation dose to the patient.

Adult↗
PubMed1982

Some remarks on 99Mo-99mTc generator kinetics.

Attention is drawn to some erroneous and incomplete pieces of information on 99Mo-99mTc generator kinetics published in the literature. The assumption that 99mTc is eluted completely from the generator leads to the incorrect 99TmTc activity-time curve plotted in some papers. It is shown that the time at which 99mTc activity in the generator reaches the maximum value depends on the efficiency of 99mTc separation. The expression derived on by authors allows the prediction of 99mTc activity available in the second separation performed several hours after the previous separation.

Kinetics↗
PubMed1999

Rapid renal single-photon emission tomography by continuous infusion of iridium-191m.

Continuous infusion of iridium-191m (t1/2 = 5 s), produced with an 191Os/191mIr generator, was used to obtain rapid high-resolution single-photon emission tomography (SPET) of renal blood flow in the rabbit. SPET scans of the abdomen were obtained with a triple-detector SPET system (MS3, Siemens Gammasonics). The generator was eluted at a flow rate of 3 ml/min, which delivered a steady-state dose of 170 MBq (4.5 mCi) of 191mIr. The total 191Os breakthrough was 850 kBq (23 microCi). A 5-min SPET acquisition recorded a total of 2.8 million counts, resulting in images of high technical quality. Volume-rendered images clearly showed the abdominal aorta, splenic artery, spleen, renal arteries, kidneys and splanchnic vasculature. Tomographic slices through the kidneys revealed tracer primarily within the renal cortices without visualization of the collecting system. The estimated effective dose equivalent for a 5 min infusion of 191mIr at a steady-state dose of 170 MBq is 0.74 mSv compared with 2.7 mSv from a 170 MBq dose of 99mTc-DMSA. This study demonstrates the feasibility of high-resolution SPET of regional renal perfusion in the rabbit by continuous intravenous infusion of 191mIr. The renal distribution of continuously infused 191mIr is largely within the cortices, with minimal or no detectable activity in the region of the renal pelvicalyceal system. Using this technique, cortical renal SPET can be completed much more rapidly (< 5 min) than with conventional renal cortical imaging agents, which suggests that this technique could be applied to the observation of rapid changes in renal perfusion such as those resulting from pharmacologic intervention, obviating the need for the patient to return for additional visits. Additional studies are required to (a) validate the methodology in larger animals prior to considering the potential for use in human beings, (b) optimize the generator design for continuous infusion, and (c) evaluate the changes in the distribution of 191mIr that occur in animal models of altered renal perfusion.

Animals↗