Patent ID: 8167805

Claim:
A method of applying therapeutic energy to a target region comprising a blood vessel, comprising: emitting a first ultrasonic pulse from a first ultrasound transducer to tissue at a target point within the target region; detecting a first ultrasonic echo from the blood vessel at a second and third ultrasound transducer, wherein the first ultrasonic echo is not detected at the first ultrasound transducer; emitting a second ultrasonic pulse from either the second or third ultrasound transducer to the target point; detecting a second ultrasonic echo from the blood vessel at the first ultrasound transducer and the non-transmitting second or third ultrasound transducer, wherein the second ultrasonic echo is not detected at the transmitting second or third ultrasound transducer; comparing the echoes to previously recorded echoes to determine time shifts or phase differences between the detected echoes and the previously recorded echoes; determining the amount of relative tissue movement using the time shifts or phase differences and pre-determined unit vectors of each ultrasound transducer; adjusting a focus of a therapeutic ultrasound applicator based at least in part on the determined amount of relative tissue movement to keep the target point within the focus of the therapeutic applicator; and emitting a dose of therapeutic ultrasonic energy from the therapeutic ultrasound applicator such that the target point is exposed to the dose.