NEAR-REAL-TIME 3D ULTRASONIC STRAIN IMAGING

This paper describes a near-real-time system for acquiring and displaying 3D ultrasonic strain images using a mechanical sector transducer. For improved image quality and robustness, all signal processing is fully 3D, including 3D data windows, 3D least-squares fitting for the displacement-to-strain calculation, 3D strain normalization and full displacement tracking in the axial, lateral and elevational directions. Notwithstanding this thorough signal processing, 3D strain volumes are typically available for inspection within 20 seconds of performing the scan, with no need for special hardware. The speed is achieved by iterative phase-zero displacement tracking in the axial direction and novel methods for tracking in the lateral and elevational directions. Since the displacement tracking does not rely on the common (but brittle) zero-displacement assumption at the transducer face, high quality strain images are obtained reliably. The paper includes examples of in vitro strain images with full details of the acquisition and processing times.