Radium-223 is a radioactive isotope of radium that emits alpha particles. It is primarily used in medical treatments, particularly for patients with advanced prostate cancer that has spread to the bones. The alpha particles emitted by Radium-223 can target and destroy cancer cells while minimizing damage to surrounding healthy tissue. This isotope has a half-life of about 11.4 days, which means it decays relatively quickly. It is administered through an injection, allowing it to concentrate in areas of bone metastasis. Radium-223 is part of a broader category of treatments aimed at improving the quality of life for cancer patients.