Technetium-99m is a radioactive isotope commonly used in medical imaging. It emits gamma rays, which can be detected by special cameras to create detailed images of organs and tissues in the body. This makes it valuable for diagnosing various conditions, including heart disease and cancer. The isotope has a short half-life of about six hours, meaning it decays quickly and minimizes radiation exposure to patients. Technetium-99m is often used in a variety of radiopharmaceuticals, allowing doctors to visualize different parts of the body effectively and safely during procedures like nuclear medicine scans.