Field size definition on cobalt teletherapy machines.
D003037:Cobalt Radioisotopes / Q000008:administration & dosage*; D006801:Humans; D009369:Neoplasms / Q000532:radiotherapy; D011867:Radioisotope Teletherapy / Q000295:instrumentation*; D011879:Radiotherapy Dosage
D003037:Cobalt Radioisotopes