Ultrasound technology has been widely used in medical imaging. Techniques using phased array transducers use an array of transducer elements to transmit a focused beam into the body, and each element then becomes a receiver to collect the echoes. The received echoes from each element are dynamically focused to form an image. These systems assume a constant acoustic velocity in the tissue of 1540 m/s while steering and focusing the beam. However, soft tissues have a range of acoustic velocities that vary from 1470 m/s for fat to 1665 m/s for collagen [1]. The acoustic wavefront propagation through a region with locally different acoustic velocities will be phase shifted relative to the rest of the wavefront. This effect is known as phase aberration. The effects of phase aberration include broadening of the system point spread function that deteriorate the image resolution, and increasing the off-axis response leading to multiple images for the target [2].

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