Mid- to high-power ultrasound imaging arrays - from ARFI to HIFU

Applications exist in medical ultrasound which require probes capable of both high quality diagnostic imaging and radiating higher average power into tissue. Using conventional materials and array configurations it is difficult to simultaneously achieve both objectives. This paper presents results towards an approach capable of achieving equivalent or slightly improved imaging performance compared to conventional imaging arrays while at the same time also achieving enhanced power delivery capability. An analysis is presented of the performance of piezoceramics designed for medium to high power operation (e.g. PZT4 and PZT8) in single layer and multilayer form. Arrays fabricated with different single layer piezoceramics are compared, including pulse-echo waveform and spectrum, imaging performance, and heating under high power drive. A prototype array constructed with both single layer and 3-layer PZT8 elements shows improved power delivery from the 3-layer elements. Simulations made using the measured high power multilayer properties show equivalent or improved imaging performance relative to conventional arrays.