Radiopharmaceuticals are drugs containing radioactive isotopes used for the diagnosis, the monitoring or treatment of a disease. Radiopharmaceutical used for imaging emit penetrating radiation that can be detected by external devices and for targeted therapy emit ionizing radiation locally at the tumor site.

Peptide receptor radionuclide therapy (PRRT) is a form of targeted cancer therapy. It consists of a small peptide, or a peptide analog, that is coupled to a radionuclide.