Abstract: The invention contemplates an ultrasonic body treatment system wherein a body applicator is self-contained unit with its own radio-frequency oscillator/driver, factory-pretuned to its own transducer. A remote-control unit supplies control signals via optical coupling to the oscillator-driver of the body-applicator unit. Another optical coupling from the body-applicator unit to the remote-control unit enables fidelity of applicator performance to be monitored at the remote-control unit. A safety interlock at the body-applicator unit precludes transducer operation in the absence of adequate coupling to a patient's body. The remote-control unit can thus provide all supervisory and control functions for the body-applicator unit without any electrical interconnection between these units.