Cobalt on the way out.
Buchanan
R
R
D003037:Cobalt Radioisotopes / Q000627:therapeutic use*; D006801:Humans; D009369:Neoplasms / Q000532:radiotherapy; D010315:Particle Accelerators / Q000706:statistics & numerical data; D011867:Radioisotope Teletherapy / Q000706:statistics & numerical data*; D006113:United Kingdom
D003037:Cobalt Radioisotopes