Gaëtan Marti

Biopsy Navigator: A Smart Haptic Interface for Interventional Radiological Gestures

Abstract The VRAI group at EPFL is conducting research in the fields of virtual reality and haptics (force-feedback) for medical applications. In particular, we have developed visualization techniques for medical images from various sources, and a high-performance haptic interface. In this paper, we present a technique that combines visualization with haptic rendering to provide real-time assistance to medical gestures. To demonstrate this technique, we have developed the BiopsyNavigator, a system that provides haptic feedback to the surgeon using patient specific data. Before the biopsy, it provides the surgeon with the ability to simulate the intervention. During the biopsy, haptic feedback is used to first help the surgeon to find the target and to define the optimal trajectory, then to physically guide the surgical gesture along the chosen path. Finally, haptic information is used to indicate that the target has been reached. Future developments will include real-time update of the patient model from various sources, including C-arm mounted CT and ultrasonic probes.

Image-guided surgical microscope with mounted minitracker

A new image-guided microscope using augmented reality overlays has been developed. Unlike other systems, the novelty of our design consists in mounting a precise mini and low-cost tracker directly on the microscope to track the motion of the surgical tools and the patient. Correctly scaled cut-views of the pre-operative computed tomography (CT) stack can be displayed on the overlay, orthogonal to the optical view or even including the direction of a clinical tool. Moreover, the system can manage three-dimensional models for tumours or bone structures and allows interaction with them using virtual tools, showing trajectories and distances. The mean error of the overlay was 0.7 mm. Clinical accuracy has shown results of 1.1-1.8 mm.

Calibration of a surgical microscope with automated zoom lenses using an active optical tracker

In this paper, we present a new method for the calibration of a microscope and its registration using an active optical tracker.

A contour method for real-time range image parsing

Real-time or near real-time range images are available from a variety of sources. Many proposed uses for these devices require significant post-processing to extract relevant 3-D information. We propose a new method based on a generalization of contour maps that has several advantages over current methods in tasks such as terrain reconstruction and obstacle avoidance. The method is illustrated with examples from obstacle avoidance on a mobile robot.