Theory and method to enhance computer-integrated surgical systems

Image-guided surgical systems and surgical robots are primarily developed to provide patient benefits through increased precision and minimal invasiveness. Furthermore, robotic devices may allow for refined surgical treatment that is not feasible by other means. The goal of my research was to develop new methods and algorithms to support image-guided systems, increase their accuracy and safety with intra-operative tracking, error reduction and advanced control. Three specific areas have been targeted for improvement, each addressed within a research project. One of the major challenges with integrated surgical robot systems is to maintain the accuracy of the pre-operative registration procedures, and to ensure that all motions of the hardware setup or drift of the patient are promptly noticed. By applying my approach, it becomes possible to rely on the navigation system as an additional reference base to identify events of motion (named surgical cases). It is feasible to accurately monitor and compensate for any spatial changes with a selective algorithm. The concept I have developed was tested on a neurosurgical prototype system built at the Johns Hopkins University (Baltimore, USA), incorporating a navigation system and an interventional robot. The new technique can be used with various image-guided systems, offering new ways to enhance their capabilities. In certain critical surgical procedures, physicians extensively rely on the help of navigation systems, with accuracy metrics provided by the manufacturers. Depending on the setup, inherent system errors can accumulate and lead to significant deviation in position. It is crucial to improve the precision of integrated setups, and to determine the overall task execution error—the registration and tracking errors enlarged by multiplying imperfect homogeneous transformations. The stochastic approach I developed offers an easy and straightforward solution to map and scale the error propagation. Applying pre-operative and on-site simulations, the optimal positioning of the navigation system can be achieved. This results in faster task execution and reduction of the probability of surgical errors. Error compensation and guidance of surgical devices are gaining importance in the evolving field of long distance telesurgery. Effective control requires the appropriate handling of the latency in the communication, while ensuring the stability of the devices. I developed a framework for robotic telesurgical support of human space missions and for other long distance procedures. This incorporates the model of the interventional site with a remote controlled slave robot, the communication channel and the model of the human operator. A control structure was designed for telesurgery, relying on empirical controller design methods. It was successfully tested for robot control over a time-delay network. It is strongly believed that robotics will have the same impact on health care in the next few decades as it had on manufacturing in the past 40 years. The methods developed within the frames of the research should contribute to the field for the benefit of future projects and systems.