Development of Electronic Instrumentation For Computer-Assisted Surgery

Abstract

In the operating room, feedback, such as instrument positioning guidance provided by surgical navigation systems is typically displayed on an external computer monitor. The surgeon’s attention is usually focused on the surgical tool and the surgical site, so the display is typically out of the direct line of sight. A simple visual feedback mechanism was developed to be mounted on the surgical tool. This feedback is within the surgeon’s direct line of sight and alerts the surgeon when it is necessary to look at the monitor for detailed navigation information. The combination of visual feedback with the surgical navigation system is designed to aid the surgeon in cutting around a tumor, maintaining negative margins, while reducing the amount of healthy tissue contained within the cut. The tool-mounted visual feedback device was designed to be light-weight, compatible with electromagnetic (EM) tracking, and pose no risk of galvanic connection to the patient. The device was tested through the resection of multiple tumor contour models using computer navigation screen only, and computer navigation screen with visual feedback mounted on the surgical tool. Use of the device was shown to decrease the amount of healthy tissue contained within the surgical cut, and to increase the subjects’ confidence in their ability to follow acceptable margins. The second objective of this work is to develop a system to both spatially and temporally track electrosurgical instruments, within the surgical navigation system. In order to temporally track the tools, it is important to know when the electrosurgical unit is powered on. However, electrosurgical instruments are FDA and Health Canada approved and therefore cannot be interfered with. Thus, a non-invasive method of sensing when the tool is powered on is required. Two AC current sensors, two peak detector circuits, and one voltage comparator circuit were used to detect when an electromagnetically tracked electrosurgical cauterizer is being powered on and differentiate between the cut and coagulation modes when cauterizing different substances. This can be integrated into the existing surgical navigation system through the use of an Arduino Uno microcontroller.