ABSTRACT
The influence of the radionuclidic impurities in radiopharmaceuticals on the reading of sample activities in a dose calibrator has been studied. As a practical example, commercially available 123I was used to measure the effect of radioactive impurities on "dose calibrator" readings. The impurities present in commercially available 123I were identified and quantified by the use of a Ge(Li) detector, and the response of a dose calibrator to each impurity was determined. The contribution of radioactive impurities to sample readings was determined for each sample of 123I studied. It was found that impurities may increase the dose calibrator readings up to 31%, even though the impurities were within the warranty given by the manufacturer.
Subject(s)
Radioisotopes/analysis , Iodine Radioisotopes/analysis , Radiation DosageABSTRACT
The past, present and future development of radiopharmacology as a new branch of science is being presented. Radiopharmacological techniques have been applied by many scientists in the past, not knowing that they were developing a new scientific field. With the advancement of these techniques, the creation of a specialized teaching program and the organization of the first international symposium on radiopharmacology, the first specialized meeting in this area, radiopharmacology became a discipline standing on its own feet. The main purpose of radiopharmacology is to study the chemical properties of radiotracers, and their interactions with living organisms. In order to promote and further expand this field, an international association of radiopharmacology was created. The main purpose of the association is to congregate all those interested in the uses of radiotracers in biological sciences, including medicine, by the organization of national and international meetings.
Subject(s)
Biological Availability , Isotope Labeling , Pharmaceutical Preparations/metabolism , Radioactive Tracers , Radioisotopes , HumansABSTRACT
Occasionally, radiopharmaceuticals prepared from the eluates of 99Mo-99mTc generators that have not been eluted for several days contain large amounts of free pertechnetate, as tested by radiochromatography and biologically by administration to patients. We fing the most probable causes of poor 99mTc-labeling in these cases to be: a) the presence of a large concentration of 99TcO4-in eluants; b) insufficient stannous ions available for the complete reduction of Tc due to spontaneous oxidation of Sn in the vial and also due to oxidation of stannous ions by the presence of larger than expected concentrations of H2O2 and HO2 radicals in the eluant.
Subject(s)
Isotope Labeling/standards , Technetium , Brain/diagnostic imaging , Humans , Mouth/diagnostic imaging , Oxidation-Reduction , Pentetic Acid , Radionuclide Imaging , Salivary Glands/diagnostic imaging , Thyroid Gland/diagnostic imagingSubject(s)
Adrenal Gland Diseases/diagnosis , Pancreatic Diseases/diagnosis , Parathyroid Diseases/diagnosis , Radionuclide Imaging , Thyroid Diseases/diagnosis , Animals , Ascorbic Acid , Carbon Radioisotopes , Cholesterol , Dichlorodiphenyldichloroethane/analogs & derivatives , Estradiol , Humans , Iodine Radioisotopes , Phenytoin , Selenomethionine , TechnetiumSubject(s)
Iodine Radioisotopes , Thyroid Gland/diagnostic imaging , Absorption , Half-Life , Humans , Radiation Dosage , Radionuclide ImagingABSTRACT
Although the current use of 51Cr for the evaluation of monocyte chemotaxis has yielded encouraging results, certain properties of this radionuclide leave room for improvement. Technetium-99m was evaluated as an alternative label for this purpose. A cell loss of 50% was found, but the recovered cells showed excellent viability and function. Chemotaxis was measured using a modified Boyden's chamber and a lymphocyte-derived chemotactic factor. The chemotactic properties of 99mTc-labeled human monocytes were preserved, and an excellent correlation between radioactive measurement and microscopic counting of migrating cells was observed.
Subject(s)
Chemotaxis, Leukocyte , Isotope Labeling/methods , Monocytes , Technetium , Humans , In Vitro Techniques , Monocytes/physiologyABSTRACT
The effectiveness of three commercial bone scintigraphic agents and freshly made stannous chloride in labeling erythrocytes with 99mTc was compared. Our results indicate that tin pyrophosphate is the agent of choice and that it is most effective when injected at least 15 minutes before the 99mTc-pertechnetate is administered. This technique of labeling red blood cells in vivo could be applied in performing blood pool studies.
Subject(s)
Erythrocytes , Technetium , Animals , Binding Sites , Diphosphonates , Dogs , Isotope Labeling , Tin , Tin PolyphosphatesABSTRACT
Current techniques for determining the radiochemical purity of 99mTc-labeled radiopharmaceuticals are limited by the variety of compounds that can be tested or the length of time required to complete the test. A chromatographic method, based on the use of two solvents (0.9% saline and acetone) and a stationary phase made of silica-coated cellulose strips, solves these problems for water-soluble 99mTc-labeled radiopharmaceuticals. With this method, the oxidation state of unbound 99mTc and the labeling yield of 99mTc-labeled radiopharmaceuticals can be quickly determined: the whole procedure takes only a few minutes to run. This system compares favorably with lengthier procedures and with a commercially available kit.
Subject(s)
Technetium , Chromatography/methods , Diphosphates , Isotope Labeling , Pentetic Acid , Quality ControlABSTRACT
Venograms were obtained on dogs in which venous thrombosis had been surgically induced. Radionuclide venograms, obtained after injection of 99mTc-labeled microspheres or macroaggregated albumin, showed decreased radioactivity over the areas of venous thrombosis and increased radioactivity over areas of venous stasis. Scintigrams of veins excised after an injection of labeled particles did not delineate thrombi, areas of crush-injured vein, or the venous valves. Delay in the washout of radioactivity on a venogram indicates stasis due to impeded venous flow in the area of thrombosis. A modified technique was developed to obtain simultaneous images of the superficial and deep veins of the leg. Visualization of the superficial veins not only permits detection of superficial abnormalities, but also assists interpretation of the venographic observations of the deep veins.
Subject(s)
Radionuclide Imaging , Saphenous Vein , Thrombosis/diagnosis , Animals , Dogs , Female , Humans , Male , Microspheres , Serum Albumin , TechnetiumABSTRACT
The radiation dose to patients from RISA, sodium iodohippurate, and rose bengal labeled with commercially available 123I and its accompanying radioimpurities has been studied. The extra radiation dose to target organs was found to range from 29% to 97% that due to 123I alone when the radiopharmaceutical is administered at calibration time. Additional delay in the time of administration increases the relative impurity dose.
Subject(s)
Iodine Radioisotopes , Drug Contamination , Female , Humans , Iodohippuric Acid , Male , Pregnancy , Radiation Dosage , Rose Bengal , Serum Albumin, Radio-Iodinated , Time FactorsSubject(s)
Mannose , Radioisotope Renography , Technetium , Animals , Dogs , Male , Rabbits , Rats , Sugar Acids , TinABSTRACT
Stable labeling of red blood cells (RBCs) with 99mTc, in yields of about 66%, was achieved by using stannous chloride as a reducing agent. In a study of 12 patients, the stability of technetium-labeled RBCs in the circulation varied significantly among individuals, but the average biologic half-life of the labeled cells was 16.8 hr. Although the labeling yield was lower when the labeling was carried out without EDTA with the addition of stannous chloride after the pertechnetate, this sequence appears to be the best for labeling RBCs for use in obtaining images of the blood pool or the cardiovascular system because of the increased viability of the RBCs.
