Theranostics (a portmanteau of words therapy and diagnostics) in nuclear medicine is a concept based on the use of the same molecule that is related to a specific molecular target (membrane receptor or metabolite) and labeled with diagnostic and therapeutic radionuclides. Such molecules, i.e., radiopharmaceuticals, are used primarily in oncological indications, in which diagnostic radionuclides attached to the same vector molecule can be replaced by therapeutic ones, to destroy the tumor cell DNA. Neuroendocrine tumors are rare tumors with manifestations that vary depending on the tumor-affected organ or organs. Their characteristic is that they show increased expression of somatostatin receptors on their cell membrane. Somatostatin is a neuropeptide whose radiolabeled, longer-lived analogs are used for diagnosis, disease monitoring, and radionuclide therapy. Radionuclide therapy is based on the theranostic principle in which, on the same specific vector molecule, diagnostic radionuclides (68Ga, 99mTc, 111In) are replaced by therapeutic ones (90Y, 177Lu) which, thanks to beta minus radiation, interact with the organ(s) of interest. The diagnostic segment of theranostics is related to the preparation, application of radiopharmaceuticals to patients, and imaging with gamma and PET cameras. In this part, the role of the bachelor of radiological technology is clearly defined. The therapeutic segment is more complex and involves a team of experts including nuclear medicine specialists, oncologists, medical physicists, nurses, and bachelors of radiological technology, whose role in this segment is less recognized than in diagnostics which is performed more often. They are involved in work in a hot laboratory where radiopharmaceutical is prepared for injection, in patient and therapy room preparation, but is also important in other segments of this process, especially when the physicist is not available.