Radiopharmaceuticals are a class of drugs that contain radioactive substances, known as radioisotopes, which are used for diagnostic or therapeutic purposes in nuclear medicine. These drugs are designed to target specific organs, tissues, or cells in the body in order to visualize or treat diseases such as cancer, cardiovascular disorders, and neurological conditions. Radiopharmaceuticals emit gamma radiation, which is detected by imaging devices (such as PET or SPECT scanners) to create detailed images of the body's internal structures or to deliver targeted radiation therapy to diseased tissues. Researchers in the field of radiopharmaceuticals work to develop new drugs, improve existing formulations, and study their safety and efficacy in clinical settings.