Labelling with positron emitters of pnicogens and chalcogens

The increasing importance of the positron emission tomography (PET) in clinical diagnosis led to the development of a multitude of radiotracers labelled with positron-emitting radionuclides of groups 15 (pnicogens) and 16 (chalcogens) of the periodic table of elements. The positron emitters of the endogenous occurring elements nitrogen, phosphorus, oxygen, and sulphur are characterized by very short half-lives compared with the most commonly used PET radionuclides carbon-11 or fluorine-18. Therefore, the potential of their synthesis and possible applications in PET is challenging and limited. On the other hand, the nonstandard positron emitters arsenic-72, arsenic-74, and selenium-73 have half-lives in the range of hours to days and, thus, are of interest for PET studies of processes with long biological half-lives, but novel methods have to be developed for their application, especially in the no-carrier-added state. This review summarizes recent research concerning the positron emitters of pnicogens and chalcogens for radiolabelling applications.