<unk>  <unk> Ra, Ra-223) is an isotope of<unk>  with an 11.4-day half-life. It was discovered in 1905 by T. Godlewski, a Polish chemist from Kraków, and was historically known as actinium X (AcX).<unk>  dichloride is an alpha particle-emitting radiotherapy drug that mimics calcium and forms complexes with hydroxyapatite at areas of increased bone turnover. The principal use of<unk> , as a radiopharmaceutical to treat metastatic cancers in bone, takes advantage of its chemical similarity to calcium, and the short range of the alpha radiation it emits.
Radium-223
Strontium-90
Technetium 
Iodine-131
Technetium-99m
DOTA-TATE
Iodine 
Iodine