Radiopharmaceuticals are unique medicinal formulations containing radioisotopes which are used in major clinical areas for diagnosis and/or therapy. Targeted radiopharmaceuticals bind to specific structures such as proteins or cells within the body and thus accumulate in particular places, such as e.g. tumor lesions in a cancer patient.

If they are used for imaging, radiopharmaceuticals can detect cancer (diagnostic use) or the expression of target receptors in patients with confirmed cancer indications, in order to determine whether they are likely to respond to a therapy that binds to that specific receptor (theranostic use).

If they are used for therapy, radiopharmaceuticals can destroy target expressing cancer cells as well as neighboring tumor cells and cells from the microenvironment by direct radiation-induced cell damage and via the bystander and cross-fire effect.

If a radiopharmaceutical can be used for imaging or therapy depends on the isotope it carries. Imaging isotopes emit radiation that can be detected outside the body (usually gamma radiation or positrons), while therapy isotopes emit particles such as high energy electrons (beta particles) or helium nuclei (alpha particles). The so-called theragnostic approach combines both modalities to identify patients expressing enough therapeutic target to make them candidates for radiopharmaceutical cancer therapy.