Fully electronically steerable high power ultrasound phased arrays for therapy—A review of progress

When combined with imaging-guidance focused ultrasound (FUS) provides means for localized delivery of mechanical energy deep into tissues. This focal energy deposition can modify tissue function via thermal or mechanical interactions with the tissue. Traditionally, ultrasound has been focused using spherically curved phased arrays that allow limited electronic steering around geometric focus of the array. To have a fully electronically steered arrays requires the transducer element size to be < wavelength/2 of the ultrasound wave. One way to accomplish this is to use sparse arrays with small transducer elements, the other is to have fully populated arrays with thousands of elements and required electronic complexity. However, the electrical impedance of small transducer elements is high and their efficiency is low and it has been difficult to manufacture arrays with adequate acoustic power. In this talk we will describe how these challenges can be solved with novel manufacturing methods and how we developed complete image-guided systems for both animal and clinical testing. We will also describe our experience with these systems for both brain and body treatments.