Abstract: A catheter for delivering ultrasonic energy and therapeutic compounds to a patient's vascular system comprises an elongate outer sheath having an energy delivery section. The catheter further comprises an elongate inner core configured to be inserted into the elongate outer sheath. The elongate inner core is positioned at least partially within the energy delivery section. The catheter further comprises a plurality of ultrasound radiating members mounted along the portion of the elongate inner core within the energy delivery section. Each of the ultrasound radiating members is spaced longitudinally from the other ultrasound radiating members. The catheter further comprises an elongate drug lumen configured to deliver a therapeutic compound to the portion of the patient's vascular system adjacent to the energy delivery section.