The positron emission tomography and its applications

Emission reconstruction tomography is a branch of nuclear technology that advanced termendously during the last five years. This progress is the result of the efforts for building more powerful detection machines in nuclear medicine, of the spreading of cyclotron resarch centers and of the increasing interest in the synthesis of radiopharmaceuticals. The paper reviews the basic principles of positron emission reconstruction tomography. The detection requirements are detailed on the basis of applicability of the projection equation and the unique advantages of the positron emitters are emphasized. Among the mathematical methods that may be potentially used for the image reconstruction, the technique of lienar superposition of filtered backprojections is specifically described. The design of the tomographs are presently in biomedical use and the configuration of the prototypes under study are briefly outlined. Some actual or desirable perfomances of the emission tomographs are discussed, such as spatial resolution, counting capabilities and time of examination. An onverlook on the applications of positron emission tomography illustrates the fact that this technique opens nuclear medicine to up-to-now inaccessible investigations of physiological processes, metabolic pathways and pharmacodynamical problems.