Investigation of the feasability for 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 × 32 3 MHz array with a half wavelength pitch. The elements of the array are grouped in blocks of 16 × 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 × 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 µm. 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 gratinglobe 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.