# 1ปรนัยWhat is the main radioactive source used in Cobalt-60 teletherapy machines?UraniumThoriumCobalt-60Radium
# 2ปรนัยWhat is the purpose of a mercury shutter in a teletherapy machine?To cool the machineTo shield radiation when not in useTo increase radiation strengthTo focus the beam
# 4ปรนัยWhich component brings the radioactive source in front of the collimator opening?GantrySource housingPatient supportMachine control console