Abstract:
The feasibility of using novel ultrasound phased arrays consisting of array elements larger than one wavelength, minimizing the number of elements in an aperture through a combination of geometric focusing, directive beams, and sparse, random placement of array elements, for tissue ablation applications was examined both theoretically and experimentally. A hexagonally packed array consisting of 108 8-mm-diam circular elements mounted on a spherical shell was modeled theoretically, and a prototype array was constructed, to examine the feasibility of sparse random array configurations for focal surgery. A randomly selected subset of elements of the prototype test array (64 of 108 available channels) was driven at 2.1 MHz with a 64-channel digitally controlled rf drive system. The performance of the prototype array was evaluated by comparing field data obtained from theoretical modeling of the array configuration to that obtained experimentally via hydrophone scanning. The results of that comparison, along with total acoustic power measurements, indicate that the use of sparse random phased arrays for focal surgery is feasible, and that the nature of array packing is an important determinant to observed performance. [This research was supported by National Cancer Institute Grant No. CA66462.]