Engineers at Vanderbilt University have developed a silicon cap filled with coffee grounds to track patient head movements and orientation during delicate nose and throat surgery. The technology was recently presented at the International Conference on Information Processing in Computer-Assisted Interventions in Barcelona, Spain.
At present, patients undergoing nose and throat surgery wear a basic elastic headband studded with reflective dots that can be picked up by sophisticated tracking systems, allowing surgical systems to track where the tools are oriented inside the patient. “These are very delicate operations and a sophisticated image guidance system has been developed to help the surgeons, but they don’t trust the system because sometimes it is spot on and other times it is off the mark,” said Robert Webster, Associate Professor of Mechanical Engineering and Otolaryngology at Vanderbilt. The problem with the current system is that surgeons can inadvertently move or knock the headband so that it slips out of position on the patient’s head, throwing out their measurements.
Current elastic headband used for tracking the position of a patient’s head during endonasal surgery is on the right. The granular jamming cap that fixes the registration points more firmly is on the left. Images credit: Joseph Howell / Vanderbilt
The Vanderbilt team began to develop a better way to attach the reflective markers to a patient’s head. The design they came up with involves coffee grounds inside a cap that’s similar to a swimming cap. The patient places the cap on their head and then a vacuum is applied, making the coffee grounds inside become really rigid (think of your favorite vacuum-packed coffee). This tightly draws the cap to fit the contours of the patient’s skull. The reflective dots are studded on the outside of the cap and are much more resistant to slipping during surgery.
An existing alternative was always directly drilling the dots into a patient’s skull, so the new technique is much less invasive. “It’s a very clever way – that doesn’t involve drilling holes in patients’ skulls – to greatly improve the accuracy of the guidance system when we are operating in the middle of a person’s skull: a zone where the accuracy of the current system is inadequate,” said Paul Russell, Assistant Professor of Otolaryngology at Vanderbilt.
See the coffee cap in action here:
