Radioactive nuclei for $\beta^+\gamma$ PET and theranostics: selected candidates

PET is an established medical diagnostic imaging method. Continuous improvements are aimed at refining image reconstruction, reducing the amount of radioactive tracer and combining with targeted therapy. TOF-PET provides the localization of the tracer through improved time resolution, nuclear physics may contribute to this goal via selection of radioactive nuclei emitting additional $\gamma$-rays. This additional radiation, when properly detected, localizes the decay of the tracer at the line of response determined by two detected 511 keV quanta. Selected candidates are presented. Some are particularly interesting, as they are strong candidates for theranostic applications.