Actinium-227 is a radioactive isotope of the element actinium, which is part of the actinide series in the periodic table. It has a half-life of about 21.6 years and decays primarily through alpha emission. This means it releases alpha particles as it transforms into other elements, including francium-223 and radium-223. Actinium-227 is found in trace amounts in uranium and thorium ores. It is used in various applications, including targeted alpha therapy for cancer treatment, where its radioactive properties help to destroy cancer cells while minimizing damage to surrounding healthy tissue.