A method of delivery ultrasonic energy and a therapeutic compound to a treatment site and an ultrasonic catheter system are disclosed. The ultrasonic catheter system comprises a tubular body having a proximal end, a distal end and a treatment zone located between the distal end and the proximal end, a fluid delivery lumen, at least one ultrasound radiating element positioned in the treatment zone, wiring electrically coupled to the at least one ultrasound radiating element and extending through the tubular body and terminating at a connector, and a control system comprising external circuitry and an isolation pod that is configured to be electrically connected to the connector, the isolation pod being positioned between the tubular body and the external system and comprising an isolation barrier and circuitry for driving the ultrasound radiating element.