Yttrium.

The radioactive isotope 90Y is mainly used to treat various cancers, including lymphomas, leukaemia, ovarian cancer, pancreatic cancer, bone cancer and colorectal cancer. This isotope will adhere to monoclonal antibodies, which in turn will bind to the cancer cells and kill them by emitting beta particles owing to the decay of 90Y.

Needles made of 90Y can also cut more accurately than scalpels and have been used to cut pain-transmitting nerves in the spinal cord.

90Y is also used in radionuclide synovectomy to treat inflamed joints, particularly knees, in patients suffering from conditions like rheumatoid arthritis.