Speed-up of acoustic simulation techniques for 2D sparse array optimization by simulated annealing

This work deals with the design of optimized 2D sparse arrays transducers for 3D ultrasound imaging. With respect to the approaches based on simplified acoustic models of the single element pressure radiation, a more realistic acoustic simulation software (Field II) unfortunately yields long processing times. As a consequence, ways to accelerate the acoustic simulation of the radiated beam pattern are needed, especially if such calculation is integrated at each step of the optimization process. An additional motivation of the simulation acceleration is that according to simulated annealing theory the more iterations the better are the obtained solutions. To drastically speed-up the simulations, a fast pressure field update algorithm and a method to reduce the amount of pressure measurement points are presented. The two approaches were applied together to optimize a 256-element 7 MHz sparse array probe achieving a 75 speed-up gain.