In one embodiment, a method for treating a vascular occlusion in a patient's body comprises exposing the vascular occlusion to an external ultrasonic energy field that is generated outside the patient's body. The method further comprises positioning an ultrasound radiating member in the patient's body in the vicinity of the vascular occlusion. The method further comprises exposing the vascular occlusion to an internal ultrasonic energy field that is generated by the ultrasound radiating member. The method further comprises using the ultrasound radiating member to detect a first characteristic of the external ultrasonic energy field. The method further comprises adjusting a second characteristic of the external ultrasonic energy field based on the detected first characteristic of the external ultrasonic energy field.