Samarium

Definition of samarium Sm 153
National Cancer Institute

samarium Sm 153

(suh-MAYR-ee-um ...)
A radioactive substance used to treat bone cancer and other cancers that have spread to the bone. Samarium Sm 153 is a radioactive form of the element samarium. It collects in bone, where it releases radiation that may kill cancer cells.

Source: NCI Dictionary of Cancer Terms