Controlled high efficiency lesion formation using high intensity ultrasound

A method for administering an ultrasonic therapy, comprising the steps of:

• (a) providing at least an ultrasonic transducer that emits a focused high intensity ultrasonic energy when energized;
• (b) positioning the at least ultrasonic transducer proximate an undesired tissue;
• (c) positioning a focal point of the at least an ultrasonic transducer to a distal boundary of the undesired tissue;
• (d) energizing the ultrasonic transducer and applying a sufficient thermal dose of focused high intensity ultrasonic energy to form an initial tissue lesion located at the distal boundary of the undesired tissue;
• (e) initiating pre-focal heating of the undesired tissue to a sufficient temperature wherein at least one acoustic absorption characteristic of the heated undesired tissue is enhanced;
• and
• (f) using at least one of an f-number, an intensity, and a time of the focused high intensity ultrasonic energy to cause the initial lesion to grow toward the ultrasonic transducer and in at least one other dimension, but not substantially beyond the distal boundary of the lesion.