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At least 19 recordsLinked to original sources
PubMed2002

The planning and design of a new PET radiochemistry facility.

The objectives of the Mayo positron emission tomography (PET) radiochemistry facility are the production of PET drugs for clinical service of our in-house patients, commercial distribution of PET drug products, and development of new PET drugs. The factors foremost in the planning and design phases were the current regulatory climate for PET drug production, radiation safety issues, and effective production flow. A medium-energy cyclotron was preferred for its small footprint to allow a compact vault, its high-proton energy to offer a higher product radioactivity; and its research capabilities. A vault installation was chosen instead of a self-shielded machine for improved access and ease of maintenance. Adjacent to the cyclotron is an area that houses the support equipment and a large dedicated workshop to support machine maintenance and targetry development. The total floor area of the PET radiochemistry facility is 344.2 m(2) (3,705.5 ft(2)), of which the radiochemistry laboratory occupies 130.7 m(2) (1,407 ft(2)). To reduce environmental contamination of PET drug products, the laboratory contains a controlled-air environment class 10,000 (M5.5) clean room with access via an interlocking entry change area. A fully shielded isolator (class 100 [M3.5]) is located in the clean room. The PET drugs are delivered via shielded tubing between the synthesizer and isolator. Inside the isolator, there is an automated device for dispensing the PET drug into either a bulk-activity vial or a unit-dose syringe. The dispensed PET radiopharmaceutical then passes through a hatch to a dedicated area where it is packaged for in-house use or commercial distribution. Unit doses for in-house patients are transported via pneumatic tube to the PET imaging area 76.2 m (250 ft) away. There is extensive radiation area monitoring throughout the facility that continuously measures radiation levels. We believe that our new PET radiochemistry facility not only meets overall objectives, but also provides an ergonomic, efficient working environment for the production and development of PET drugs.

Journal Article↗
PubMed1994

Synthesis and radiochemistry of 2,4-disubstituted 17 alpha-iodovinylestradiols.

This report details the preparation of three compounds which are structurally designed to have depressed metabolism and/or conjugation: 2,4-dibromo-, 2,4-dichloro-, and 2,4-dimethyl-17 alpha-iodovinylestradiol. Their synthesis includes the use of two novel transformations based upon tin chemistry: preparation of an intermediate 17 alpha-vinylstannanes via stannylcupration of a 17 alpha-ethynyl steroid, and preparation of the 2,4-dimethyl functionality via a palladium catalyzed coupling of 2,4-dibromoestrone acetate with tetramethyltin. The preparative radiochemistry of these three materials is also described.

Estradiol↗
PubMed2001

Radiochemical approach to the JCO criticality accident in Tokai-mura, 1999--an overview of the radiochemistry group.

A few days after the JCO criticality accident in Tokai-mura, a collaborating scientific investigation group was organized to evaluate the environmental impact of the accident. The group consisted of two groups: an environmental research group (radiochemistry group) and a biological research group. This paper overviews the scientific activity of the former group based on 6 sampling campaigns conducted at the JCO campus, Tokai-mura and Naka-machi. Some of the topical results and our remaining tasks concerning the JCO accident are discussed.

Environment↗
PubMed1994

Neutron activation analysis of biological samples at the radiochemistry division of IPEN-CNEN/SP.

Neutron activation analysis is a very useful method for determination of a great number of elements in biological samples. At the Radiochemistry Division of the IPEN-CNEN/SP, this method is being extensively applied to study several materials, such as extracts from medicinal plants, human hair, snake venoms, human lungs, food-stuffs, and corn samples. Both instrumental neutron activation analysis (INAA) and radiochemical neutron activation analysis (RNAA) are used to analyze real samples, as well as biological standard reference materials to evaluate the accuracy and precision of the results.

Brazil↗
PubMed2000

Radiochemistry: inconvenient but indispensable

Radiochemistry has always been and still is a crucial tool in the field of radionuclide determination, both for high and low level works; this holds particularly in the case of alpha and beta emitters. Requests to the analyst are increasingly demanding in terms of performance (detection limit, reliability, accuracy, precision,...), but also of economy (cost, time,...) and of flexibility with respect to sample types. In general, chemical and radiochemical analyses consist of four main steps: sample pre-treatment including pre-concentration, dissolution and/or digestion, separation of analytes from the matrix and from each other, transformation of the separated fraction into a source suited for measurement, determination of the amount or the activity of the analytes. The required combination of sub-procedures is determined by the analytes under investigation, their absolute and relative amounts, the matrix composition and by the performance required. IRMM's Analytical Chemistry Unit started several years ago to develop, adapt and/or validate various radiochemical methods and procedures, and apply these to different measurement tasks. This paper gives an overview on recent and ongoing activities.

Journal Article↗
PubMed1984

Radiochemistry and biostability of autologous leucocytes labelled with 99mTc-stannous colloid in whole blood.

Autologous leucocytes were labelled in whole blood by phagocytic uptake of 99mTc-stannous colloid. This colloid has a mean particle size of 1.5 micron and labels leucocytes with 81% efficiency. Individual cell uptakes were: granulocytes 42%, monocytes 39%. Isotonic sodium citrate added after the labelling procedure did solubilise excess colloid but was not necessary for adequate removal of excess colloid. Labelled leucocytes were shown in vitro to be viable and maintain normal bactericidal and chemotactic capacity. Biodistribution, clearance rates and dosimetry are presented. These results indicate that autologous leucocytes can be efficiently labelled with 99mTc-stannous colloid with good residual cell function.

Animals↗
PubMed2001

Nuclide migration and the environmental radiochemistry of Florida phosphogypsum.

Phosphogypsum, a waste by-product derived from the wet process production of phosphoric acid, represents one of the most serious problems facing the phosphate industry in Florida today. This by-product gypsum precipitates during the reaction of sulfuric acid with phosphate rock and is stored at a rate of about 40 million tons per year on several stacks in central and northern Florida. The main problem associated with this material concerns the relatively high levels of natural uranium-series radionuclides and other impurities which could have an impact on the environment and prevent its commercial use. We have studied the potential release of radionuclides from phosphogypsum by: (i) analysis of stack fluids, groundwaters, and soils associated with gypsum stacks; and (ii) geochemical modeling. Stack fluids were observed to be very high in dissolved uranium and 210Pb with only moderate concentrations of 226Ra. Underlying soils tend to be enriched in U and 210Pb indicating precipitation when acidic stack fluids enter a buffered environment. Modeling results showed significant increases in radionuclide complexes with sulfate and phosphate, resulting in relatively mobile uncharged or negatively charged solution species within the stacks with likely precipitation of multicomponent solids with increasing pH below the stack. Our evidence thus suggests that, while phosphogypsum stacks do contain significant quantities of dissolved radionuclides, removal mechanisms appear to prevent large-scale migration of radionuclides to the underlying aquifer.

Calcium↗
PubMed2001

[Development of theme in radiochemistry].

The disintegration rates of 222Rn and its daughters in natural water were determined successfully by the use of the integral counting method with a liquid scintillation spectrometer. A significant advantage of this method is its freedom from the quenching effect. Moreover, when plural alpha-, and beta-emitters are present, their total amounts can be determined. The simple extrapolation of integral counting curve to zero pulse-height, however, do not give the true disintegration rate for the soft beta-emitters (Emax < 200 keV), because the liquid scintillator (LS) has a relatively high detection threshold. Therefore, the zero detection threshold of the liquid scintillation spectrometer was determined by measuring standard 3H samples, and a modified integral counting method which extrapolates the integral counting curve to the zero detection threshold was proposed. The method has been successfully applied to various beta-emitters, 222Rn samples, and coloured samples of beta-emitters, giving more accurate absolute disintegration rate than the conventional integral counting method and the efficiency tracing method. In the course of the study determining 222Rn by liquid scintillation counting, we observed unexpected phenomena; the air luminescence from gaseous space above LS, and the temperature dependence of pulse-height spectra. As for the former phenomenon, we proposed a method for correcting errors due to air luminescence, a method for determining alpha-emitters by the air luminescence, and a rapid calibration method for 222Rn detectors. As for the latter phenomenon, we observed that the pulse-height spectra for alpha, and beta-emitters in LS are shifted toward higher pulse-height with decreasing temperature. We found that the fluorescence intensities of the solvent of LS (toluene) is promoted at lower temperatures, and that not only toluene, but also the fluorescence intensity of a number of aromatic hydrocarbons and aliphatic hydrocarbons show the same effect as toluene. Other unexpected results are existence of metals in number of enzymes, and discrepancies between the experimental value for Kurie plot of allowed beta-emitters and the value which would be expected according to Fermi's theory, the results of which would affect the transmission probability of potential barrier for alpha-particles.

Fluorescence↗