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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↗
PubMed2004

PET tracers and radiochemistry.

This paper provides a brief review of the radiochemistry of radiopharmaceuticals used in positron emission tomography (PET). It includes some history of PET, the basic formation of radionuclides in a cyclotron target, the processing of the precursor molecules into a useful PET radiotracer and the clinical significance and outlook for PET radiotracers. This review is based on a series of recent books and articles outlining the fundamental goals of PET and how radiochemistry plays a part in achieving these goals. It is also drawn from the literature that has been developed in PET over the last 30 years since PET became a research and valuable clinical tool. PET is a growing field and the clinical applications of the chemistry and technology have just begun to be explored. There is a great deal left to do in order to explore the full potential of PET in the clinic.

Heart Diseases↗
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↗
PubMed2003

Positron emission tomography radiochemistry.

Factors that place constraints on radio-chemists who are seeking to design and develop radiopharmaceuticals for PET imaging studies include the short half-lives of 11C and 18F, minimum radiochemical yield and specific activity requirements, and high radiation fields that are associated with multi-Curie quantities of PET radionuclides. Nevertheless, during the past 20 years, considerable progress has been made in the development and application of a variety of PET radiotracers for a range of imaging studies in human subjects. We have highlighted a few areas of radiochemistry that focused on PET radiotracers that are described in this issue. Although the number of PET radiotracers synthesized is in the hundreds [6], much work remains to develop specific and useful PET radiotracers for a host of new and exciting noninvasive imaging applications.

Animals↗
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↗
PubMed2005

Microfluidic technology for PET radiochemistry.

This paper describes the first application of a microfabricated reaction system to positron emission tomography (PET) radiochemistry. We have applied microfluidic technology to synthesise PET radiopharmaceuticals using (18)F and (124)I as labels for fluorodeoxyglucose (FDG) and Annexin-V, respectively. These reactions involved established methods of nucleophilic substitution on a mannose triflate precursor and direct iodination of the protein using iodogen as an oxidant. This has demonstrated a proof of principle of using microfluidic technology to radiochemical reactions involving low and high molecular weight compounds. Using microfluidic reactions, [(18)F]FDG was synthesised with a 50% incorporation of the available F-18 radioactivity in a very short time of 4s. The radiolabelling efficiency of (124)I Annexin-V was 40% after 1 min reaction time. Chromatographic analysis showed that such reaction yields are comparable to conventional methods, but in a much shorter time. The yields can be further improved with more optimisation of the microfluidic device itself and its fluid mixing profiles. This demonstrates the potential for this technology to have an impact on rapid and simpler radiopharmaceutical synthesis using short and medium half-life radionuclides.

Biotechnology↗
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↗
PubMed1950

Radiochemistry.

Explore the source record for details and available documents.

Radiochemistry↗
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↗
PubMed2005

Aspects of positron emission tomography radiochemistry as relevant for food chemistry.

Positron emission tomography (PET) is a medical imaging technique using compounds labelled with short-lived positron emitting radioisotopes to obtain functional information of physiological, biochemical and pharmacological processes in vivo. The need to understand the potential link between the ingestion of individual dietary agents and the effect of health promotion or health risk requires the exact metabolic characterization of food ingredients in vivo. This exciting but rather new research field of PET would provide new insights and perspectives on food chemistry by assessing quantitative information on pharmocokinetics and pharmacodynamics of food ingredients and dietary agents. To fully exploit PET technology in food chemistry appropriately radiolabelled compounds as relevant for food sciences are needed. The most widely used short-lived positron emitters are (11)C (t(1/2) = 20.4 min) and (18)F (t(1/2) = 109.8 min). Longer-lived radioisotopes are available by using (76)Br (t(1/2) = 16.2 h) and (124)I (t(1/2) = 4.12 d). The present review article tries to discuss some aspects for the radiolabelling of food ingredients and dietary agents either by means of isotopic labelling with (11)C or via prosthetic group labelling approaches using the positron emitting halogens (18)F, (76)Br and (124)I.

Chemical Phenomena↗
PubMed2005

Overcoming ICP-QMS instrumental limitations for (99)Tc determination in environmental solid samples using radiochemistry.

Besides its capabilities, quadrupole-based ICP-MS counting establishes several limitations on (99)Tc analysis in environmental samples. Overcoming these limitations requires the use of radiochemical methods. We have developed a new method for the detection of (99)Tc by ICP-QMS in solid environmental samples. In order to improve the limit of detection of the technique, high amounts of solid samples (> or = 100g) are used. Hence, great amounts of the interfering elements are involved in the process, and therefore special emphasis is put on achieving a good commitment between adequate matrix elements removal and a minimization of the limit of detection. The performances of the method are analyzed in terms of conveniently defined figures of merit. The developed method is applied to several fallout level samples. In this way, the real performances and especially the real limitations of this method are shown.

Mass Spectrometry↗
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↗