Investigation of the feasibility of 3D synthetic aperture imaging

This paper investigates the feasibility of implementing real-time synthetic aperture 3D imaging on the experimental system developed at the Center for Fast Ultrasound Imaging using a 2D transducer array. The target array is a fully populated 32 x 32 3 MHz array with a half wavelength pitch. The elements of the array are grouped in blocks of 16 x 8, which can simultaneously be accessed by the 128 channels of the scanner. Using 8-to-1 high-voltage analog multiplexors, any group of 16 x 8 elements can be accessed. Simulations are done using Field II using parameters from a 32 x 32 elements experimental array made by Vermon with a center frequency of 2.93 MHz, fractional bandwidth of 58 %, and a pitch of 300 mum. The simulations show, that using all of the 128 elements a spherical wave within 50 degrees sector can be created. The level of the edge waves is reduced by applying apodization with an elliptic footprint. The results of simulations show that the angular resolution at -6dB is 2.7 degrees, and is determined by the distance between the outer-most transmit elements. The peak grating-lobe levels are -23.5, -25, 27.2, -44.5 dB below the main peak for 64, 100, 144, and 169 transmit events, respectively. The number of scanned volumes per second for these cases are 78, 50, 34 and 30, respectively.