Positron emitter radiopharmaceuticals labeled with

Design of radiotracers and radiopharmaceuticals labelled with a short-lived positron emitter The case of fluorine-18... 

Whilst the work that we focus on in the first part of this chapter concerns the preparation of tritium- and inevitably deuterium-labeled compounds, examples are given where the benefits can also be applied to the carbon ( C, and C)-labeled area [8]. Also discussed is the use of microwaves in the synthesis of radiopharmaceuticals labeled with positron emitters, such as carbon-11 (ti/2 = 20.4 min) and fluorine-18 (ti/2 = 109.7 min). The short half lives of these radioisotopes, together with the requirements for high radiochemical yield (RCY), radiochemical purity (RCP) and specific activity (SA) can benefit from the advantages that micro-waves provide [8, 9]. 

Hot atom chemical techniques are available in production of radiopharmaceuticals labeled with short-lived positron emitters such as and (Iwata and Wolf 1992). These... 

Since emission tomography requires some type of internal radioactive sources, a large number of radionuclides have been developed and produced specifically for these applications. Gamma emitters are used for SPECT, while positron emitters are used for PET. The chemical form of a radionuclide is tailored specifically for a given target (tissue, bone, or organ). Compounds labeled with radionuclides for administration to patients are known as radiopharmaceuticals. 

Positron decay occurs in proton-rich nuclei. In this case, the positron (or p+ particle) is originated by conversion of a proton into a neutron, along with the emission of a neutrino to conserve the energy. Positrons are the antiparticle of electrons. In a very fast process (10 12s), emitted positrons collide with an electron of a nearby atom and both particles disappear in a process called annihilation. The necessary conservation of mass and energy accounts for the transformation of the mass of both particles into energy, which is characteristically emitted in the form of two 511-keV photons almost in opposite directions. Consequently, positron emitters are used to label radiopharmaceuticals produced with diagnostic purposes by imaging. 

Some Positron Emitters of Clinical Interest Fluorine-18 is undoubtedly the most widely used positron-emitting radionuclide. This is mainly due to the wide use of 18FDG, the PET radiopharmaceutical that has permitted PET to become an everyday clinical tool. With the exception of 18FDG and probably 18FDOPA, the use of other 18F-labeled radiopharmaceuticals is very limited. However, the chemical and physical characteristics of 18F are excellent ... 

Positron emission tomography an imaging technique that makes use of a radiopharmaceutical that is labelled with a positron emitter (e.g. C, F). 

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