Video Tracking of Tuohy Needle for an Enhanced Epidural Simulator User Interface

A real time motion tracking image processing system was developed for tracking movement of a Tuohy epidural needle. The aim is to use the tracking system to plot 3D movement and rotation of the Tuohy needle to create an enhanced user interface for an epidural simulator. When the needle is angled on its plane or rotated on transverse plane for paramedian insertion the algorithm calculates these angles. The tracker provides a 5-DOF (Degrees of freedom) input option. The image tracker controls a graphical simulation of needle insertion in which a Tuohy needle can be inserted at any location on the patient’s back. As the needle is moved, the virtual needle is moved to the corresponding location in the simulation giving an intuitive interface without using a keyboard or mouse. The image tracking algorithm works by using colour segmentation image processing with a red colour marker on the needle tip. Tracking of the needle position and needle angulation were possible in excess of 10 frames per second even with changes to lighting. A second device is incorporated which measures the pressure of saline inside the syringe barrel so that the simulation can respond to applied pressure.