Nuclear medicine uses radiopharmaceuticals to image the body and treat disease. Radiopharmaceuticals are radioactive drugs that localize in specific organs or tissues.
Nuclear medicine uses radiopharmaceuticals to image the body and treat disease. In contrast to diagnostic radiology, which delivers only anatomical information, nuclear medicine imaging is unique in that it can visualize organ function. Nuclear medicine can provide medical information that otherwise may be very difficult or impossible to obtain. Radiopharmaceuticals are radioactive drugs that localize in specific organs, bones, or tissues. Nuclear medicine uses very small amounts of radiopharmaceuticals to diagnose and and treat disease. The diagnostic radiopharmaceuticals used in nuclear medicine emit gamma rays that can be detected externally by gamma or PET cameras. The most frequently used radioisotope for nuclear medicine imaging is technetium-99m (99mTc). Others include indium-111 (111In), fluorine-18 (18F), gallium-66, 67, 68, copper-64, (64Cu). Techetium-99m is a single photon emitter (SPECT imaging) and it is used in about 85% of all diagnostic applications. Fluorine-18 is a positron emitter (PET imaging). The fluorine-18 labeled D-glucose (FDG, 2-fluoro-2-deoxy-D-glucose) is currently the most frequently used PET agent. PET offers functional and metabolic imaging and commonly used in oncology applications. Using diagnostic radiopharmaceuticals, nuclear medicine can image every major organs including abdomen, brain, blood, breast, liver,heart, kidney, lymphatic system and bones. Nuclear medicine imaging procedures often identify abnormalities very early in the development of a disease. Therapeutic radiopharmaceuticals deliver therapeutic radiation to treat specific disease states. Therapeutic radioisotopes differ from diagnostics on the type of emitted radiation. For therapy, alpha or beta emitting isotopes are used. The most important beta emitters include yttrium-90, lutetium-177, samarium-153, holmium166, promethium-149. The most widely used alpha emitters are astatine-211, bismuth-212 and 213, actinium-225. A radiopharmaceutical can be targeted to a specific receptor through a targeting vector such as antibodies, antibody fragments, peptides, peptidomimetics, or small organic molecules. A very promising cancer treatment is to target the tumor with radiolabeled monoclonal antibodies or peptides.