Radiopharmaceuticals are drugs which are a combination of a vector, linker and radionuclide, each having a different function. The vector, e.g. a small molecule, peptide or antibody, is intended to specifically bind to a target tissue (target), e.g. a tumor. The more precisely the vector binds to the target and not to non-targeted tissues, organs or cells, the higher the medical benefit reducing side effects. The linker connects the vector to the radioactive payload to be delivered to the disease burden.

Depending on the type of radiation and the energy, radiopharmaceuticals can be used as a diagnostic agent (DX) or as a therapeutic agent (TX). When used as a diagnostic tool, PET (positron emission tomopraphy) or SPECT (single photon emission computed tomography) detect the radioactivity bound to the target tissue and provide visual information about the disease burden. When used as a therapeutic agent, the radiation and energy of the radionuclide (alpha or beta emitters) is used to incude DNA double strand breaks followed by cell death. Whereas the vector is often the same for the diagnostic and therapeutic agent the radionuclide differs in type of radiation and energy. This combination of diagnostic and therapeutic enables the THERANOSTIC approach of FIND, FIGHT and FOLLOW for a specific disease which offers effective personalised patient treatment.