Abstract
In spite of the relative rareness of positron annihilation into three photons, it may still be exploited to develop a new imaging modality. It would provide information not only about the local concentration of radionuclide, but also, by virtue of chemical interactions of positronium, the local chemical environment in tissue. In particular, the concentration of free oxygen could be determined, which would be a significant advantage in oncological applications of PET. The paper presents results of experimental imaging of point-like sources using the 3-photon annihilations registered by a system of three high energy resolution detectors in coincidence. After filtering out the irrelevant random coincidences images of activity distributions are reconstructed. The positions of the sources are reproduced with good accuracy. The influence of random triple coincidences arising from the predominant 2-gamma annihilations, which may contribute to image noise is discussed. The analysis of experimental results is reinforced by computer simulations.