Nuclear ftedicine is not and has not been a purely imaging discipline. It is function analysis that has always been the focal pOint. This fact has become particularly obvious in the last few years through the employment of nev short-lived radionuclides, new technical procedures and data processing. The disadvantage of function analysis in Inclear ftedicine through the use of radioactively labeled compounds is that more and more complicated and expensive equipment his to be used. A further characteristic is that these machines are stationary, and that the patients cannot be examined under physiological conditions. For technical reasons the x-camera is developing in the direction of mea suring mainly the so-ca~led 'soft' I-emitters at the present time. On the other hand, positron emitters are the radionuclides which are of interest for metabolic functions. At present, positron cameras are even more e~pensive and complicated machines, the use of which is very demanding. In this book Priv. -Doz. Dr. med. Dipl. -Ing. D. Peter pretschner has described a new system which contains his ideas and his technical developments. He describes a solution to the urgent questions and dif ficulties in the employment of radioactive substances for diagnosis. It does not demand large resources and can be used under the appropri ate individual physiological conditions. Here he was helped by his training as a natural scientist and engineer, as well as by his being an experienced clinician.