ABSTRACT
Radionuclides are applicated in many different areas including medicine. In medicine they are used for therapy as well as for diagnosis. When positron emitting radionuclides in combination with computerized tomographic systems are used, the distribution of the radioactivity can be obtained at different levels of the body and the distribution can be quantitated. The biomedical application of short-lived positron-emitting radionuclides has several advantages compared to the application of more conventional radionuclides. The availability of nuclides like carbon-11, nitrogen-13, and oxygen-15 essentially increases the range of valuable radiopharmaceuticals because metabolic organic compounds can be prepared with the same chemical and biochemical properties as the nonradioactive analogues. Carbon-11 is the longest-lived positron-emitting isotope of carbon. This radionuclide decays with a half-life of 20.4 m to stable boron-11. Carbon-11 labeled cyanides are important precursors for the syntheses of 11C-labeled organic compounds.
