Multiple focus beamforming of phased array to suppress grating lobes for HIFU

To reduce the treatment time for HIFU(High Intensity Focused Ultrasound), increasing the ablation volume by generating multiple foci can be a promising scheme. It is reported that as the number of foci increases, grating lobes are generated more. Here, we present a method to suppress grating lobes while generating a multiple focus field by setting the pressure of grating lobe regions to be zero. Among all solutions to generate desired multiple foci, one solution is found by imposing a constraint of grating lobe suppression. It is an extension of the minimum norm solution of the conventional multiple focus method. This method can be also used to protect some important tissue areas from collateral heat damage.