CORRECTION OF ACOUSTIC LENS ERROR IN SPATIAL COMPOUNDING OF ULTRASONIC DIAGNOSTIC IMAGES

Spatial compounding has been used in ultrasonic imaging for suppressing speckle noise. The technique generally involves electronically steering the ultrasonic beams. The steering angle of the ultrasonic beam is distorted by the acoustic lens structure of the probe that is used to focus the beam mechanically. These errors introduced by the lens structure cause misalignment of the ultrasonic images received at different steering angles, and consequently results in the blurred image after spatial compounding. In this paper, a solution is proposed that corrects the lens error by using image registration. The lens error was compensated by registering the wire target images before spatial compounding. An efficient registration algorithm was developed to compute the transformation matrix required for the registration. The images were registered by the transformation matrix before spatial compounding.