Design and Evaluation of a 2-D Planar Therapeutic Ultrasound Phased Array

Focused ultrasound continues to be investigated as an exciting technique for several medical therapy applications including tissue ablation. Phased array transducers serve as important devices for delivering the high intensity focused ultrasound to the targeted tissue. These arrays often produce undesired secondary foci called grating lobes that can result in heating of non‐targeted healthy tissue. Grating lobes can be eliminated by setting the element‐spacing between adjacent elements to λ/2 or less. The aim of this research was to construct and evaluate a 2‐D planar phased array with close to λ/2 element‐spacing. A 7×7 element array with element‐spacing of 0.76mm was constructed using 1,3‐piezocomposite material. Acoustic field measurements of the array focused at three different locations were taken to demonstrate its ability to scan the focus in a volume. In addition, a maximum average intensity of 5.5W/cm2 was measured for the unfocused array using radiation force techniques.