Positron-emitting nuclides

Amines labelled with positron-emitting nuclides (11C, 13N, 18F) combined with PET are useful for external measurement of the rate of transport, metabolism and excretion of a number of substances in humans and animals, and were used for various aims. After a detailed study of the organ distribution and the metabolic fate of the 13N-amines, 13N-/ -phenethylamine, 13N- -octylamine and 13N-3,4-dimethoxyphenethylamine, a general transformation path of amines in vivo has been formulated292 (equation 130). 

Positron emitting nuclides have very short half lives, on the order of minutes to tw o hours. This makes operation of a cyclotron and a radiochemistry laboratory essential to the use of PET scanners. is the longest radionuclide with a half-life of 1.87h, making a central production facility within a city feasible for radiopharmaceuticals employing this nuclide. Most clinical PET facilities have on-site cyclotrons and radiopharmaceutical laboratories to allow the use of short-lived isotopes in clinical studies. 

In general, p - and p" -Particles penetrate deep into the medium however, they do not cause damage to tissues and organs. Radionuclides that decay by p-Particle emissions are used very extensively in nuclear medicine for diagnostic and therapeutic applications. Positron-emitting nuclides are used in nuclear medicine for diagnostic purposes. p+-Emitting radionuclides are under active study for use in radiotherapy. An example... 

Spatial resolution is greater with PET, but SPECT technology is less expensive and more widely accessible in many clinical settings. In addition, positron-emitting nuclides used in PET imaging have very short half-lives 20 min 109 min) and usually require an on-site cyclotron for their production. SPECT nuclides have longer half-lives 13 h ... 

Amines labelled with positron-emitting nuclides ( C, F) combined with PET... 

One of the most recent applications of nuclear chemistry is the use of positron emission tomography (PET) in the measurement of dynamic processes in the body, such as oxygen use or blood flow. In this application, a compound is made that contains a positron-emitting nuclide such as C-11, 0-15, or N-13. The compound is injected into the body, and the patient is placed in an instrument that detects the positron emission. A computer produces a three-dimensional image of the area. 

A specialized imaging technique known as positron emission tomography (PET) employs positron-emitting nuclides, such as fluorine-18, synthesized in cyclotrons. The fluorine-18 is attached to a metabolically active substance such as glucose and administered to the patient. As the glucose travels through the bloodstream and to the heart and brain, it carries the radioactive fluorine, which decays with a half-life of just under 2 hours. When a fluorine-18 nuclide decays, it emits a positron that immediately combines with any... 

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