Cross-Wire Calibration for Freehand 3D Ultrasonography: Measurement and Numerical Issues

Abstract

3D freehand ultrasound is an imaging technique, which is gradually finding clinical applications. A position sensor is attached to a conventional ultrasound probe, so that B-scans are acquired along with their relative locations. This allows the B-scans to be inserted into a 3D regular voxel array, which can then be visualized using arbitrary-plane slicing, and volume or surface rendering. A key requirement for correct reconstruction is the calibration: determining the position and orientation of the B-scans with respect to the position sensor's receiver. Following calibration, interpolation in the set of irregularly spaced B-scans is required to reconstruct a regular-voxel array. This text describes a freehand measurement of 2D ultrasonic data, an approach to the calibration problem and several numerical issues concerned with the calibration and reconstruction.