Correction of parameter error in rotating linear probe using image registration for ultrasonic diagnostic imaging

Spatial compounding has been used in ultrasonic imaging for suppressing speckle noise. The technique generally involves electronically steering the ultrasonic beams. In this paper, we present a spatial compounding approach where the component image is acquired by mechanically rotating the probe element. A linear transducer array is rotated about an axis in the plane of the image. The goal is to avoid the problems associated with the electronic beam steering at a large angle such as decrease in the effective aperture size, grating lobe effect, and decrease in transducer sensitivity caused by obliquity factor. In the computation of the ultrasound image, we need the values of the axis of rotation and angular position of the transducer array. However, the construction of the rotation mechanism and the control system accompanies the inevitable uncertainties in these values. These parameter errors result in the target position error, and the consequence is the blurry compounded image. We present the spatial compounding for rotating linear probe in the presence of parameter error using image registration. The effect of the uncertainty in the mechanical parameters 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 component images were registered by the transformation matrix before spatial compounding and the effect of the parameter errors were removed.