An ultrasound (US) guided, CT augmented, spine needle insertion navigational system is introduced. The
system consists of an electromagnetic (EM) sensor, an US machine, and a preoperative CT volume of the patient
anatomy. Three-dimensional (3D) US volume is reconstructed intraoperatively from a set of two-dimensional
(2D) freehand US slices, and is coregistered with the preoperative CT. This allows the preoperative CT volume to
be used in the intraoperative clinical coordinate. The spatial relationship between the patient anatomy, surgical
tools, and the US transducer are tracked using the EM sensor, and are displayed with respect to the CT volume.
The pose of the US transducer is used to interpolate the CT volume, providing the physician with a 2D "x-ray
vision" to guide the needle insertion. Many of the system software components are GPU-accelerated, allowing
real-time performance of the guidance system in a clinical setting.