Freehand 3D ultrasound reconstruction for image-guided surgery

Three-dimensional (3D) ultrasound (US) is increasingly being introduced in the clinic, both for diagnostics and image guidance. Obtaining 3D volumes with 2D US probes is a two-step process. First, a positioning sensor must be attached to the probe; second, a reconstruction of a 3D volume can be performed into a regular voxel grid. Various algorithms have been used for performing 3D reconstruction based on 2D images. In this paper, we propose a new Hole-filling algorithm using Distance Weight interpolation, and we also apply it to generate the volume in our Image-guided for surgical robot. First, the ultrasound frames and position information are compounded into a 3D volume using the Bin-filling method. Then, the Hole-filling method is used to repair gaps in the volume. We define the empty voxels by sorting the neighboring voxels into three parts, and averaging them to obtain the value to fill the empty voxels according to distance weighted. The empty voxel estimation can be improved by thresholding the range width of its neighboring voxels and adjusting it to the average values. The method is tested on a Hole-manipulated volume derived from a cropped 3D ultrasound volume of chicken kidney. Our method shows improved result compared to several tested existing methods, including voxel nearest neighbour(VNN) and spline function interpolation.