Revitalising ray

s were used by Daleks to rejuvenate their organic interiors. A form of nuclear radiation, revitalising rays were taken by individual Daleks from time to time as a sort of "constitutional" in order to prolong their lives. Jeff Stone once peeked inside the personal chambers of the Emperor Dalek and caught the leader basking in the glow of the revitalising rays. (DAN: City of the Daleks)