Radiopharmaceuticals are special drugs that contain radioactive materials. They are used primarily in medical imaging and treatment. When injected into the body, these substances emit radiation that can be detected by machines like PET scanners or SPECT cameras. This helps doctors see how organs and tissues are functioning, making it easier to diagnose conditions such as cancer or heart disease. In addition to imaging, some radiopharmaceuticals are designed to treat diseases. For example, iodine-131 is used to target and destroy thyroid cancer cells. By combining the properties of radiation with pharmaceuticals, these innovative treatments offer a powerful tool in modern medicine.