6-DOF probe tracking via skin mapping for freehand 3D ultrasound

Three-dimensional ultrasound (3D US) is widely useful in clinical diagnosis and therapy monitoring. However, the existing methods for 3D US are generally expensive and physically constraining. This paper describes a low-cost and unobtrusive method for 3D US, which spatially registers 2D US scans in six degrees of freedom (6 DoF). In this method, artificial skin features are created in the scan region of the body for robust feature tracking. A lightweight camera is mounted on the US probe to track the features for probe motion recovery and skin surface mapping. This algorithm does not rely on any assumption on the scene, so this system is suitable for scan regions of any size and any surface shape. In this paper, the system design and the preparation of artificial skin features are described. Performance of this method in 3D volume reconstruction is examined quantitatively through in-vitro experiments and qualitatively through in-vivo experiments.