Hardware and software considerations in 3D ultrasound imaging of a residual limb

An ultrasound scan and data acquisition system has been developed for computer-aided prosthetic socket design. The system performs compound scan at each level of the limb by rotating an ultrasound probe around the limb to acquire 36 B-scan images. From these B-scan images, a transverse cross section of the limb is reconstructed using a spatial compounding algorithm. By scanning the limb at many levels, a 3D limb model can be reconstructed. The compound process circumvents the problems associated with the large attenuation of bones and enables reconstruction of a complete image of bones and adjoining soft tissues. In addition, the compound process reduces ultrasound speckle and improves the image quality. These benefits however, can only be achieved through careful hardware and software design. In this paper, methods and algorithms for system calibration, fast and accurate compounding, and removal of the artifacts caused by limb movement during scan are discussed.