3-D vision technology applied to advanced minimally invasive surgery systems

Summary

Current-generation vision for laparoscopic surgery involves flat two-dimensional display on a video monitor; this approach makes it difficult to accurately place the tip of a surgical instrument in the three-dimensional real space of the patient. The surgeon must rely on motion parallax, monocular cues, and other indirect evidence of depth to judge accurately the correct spatial relationship of objects in the field of view. Stereoscopic video can return accuracy to the surgeon. Critical elements in creating stereovision are the biophysical laws governing field of view, focal point, depth of field, accommodation, and convergence. In addition, engineering constraints must be followed, such as fitting a 10-mm port, which are compatible with current systems and economic feasibility.

There are two methods for 3-D vision under development which are variations on the same theme of modifying standard laparoscopes by using lenses, mirrors and prisms, and optical shuttering. One method uses two video cameras to simultaneous capture two separate images from a paired optical system. Each image is alternately transmitted to the video monitor (field sequential video) and viewed with electronic or polarizing glasses for a 3-D image. Another method uses a standard laparoscope, optically splits this one image into alternating right/left images, and reconstructs the image as above. A major challenge for both systems is that the distance between the optical elements in the laparoscope is not greater than 10 mm apart and fixed, whereas the human interpupillary distance is greater than 60 mm and can accommodate.

The application of 3-D vision technology is critical to a new, minimally invasive surgical system under development: Telepresence surgery. Using remote, dexterous, force feedback manipulators; 3-D vision; and stereophonic sound, the image at the surgical site is projected to a “computer workstation” with such convincing realism that the surgeon feels as if he were actually at the operative site. The image could also be projected from a microscopic scale, allowing performance of procedures that are simply not possible today.

Other 3-D visualization techniques under development involve CT scanning, MRI, and ultrasound, any of which could be projected over the real-time video image to enhance the surgeon's ability to perceive an operation.

Methods of displaying 3-D vision beyond simple video monitors are high-definition TV (HDTV), head-mounded displays, and possibly holograms. Also, critical patient information (vital signs and intraabdominal pressure) can overlay the video image.

The potential of 3-D vision technology has yet to be realized. In the future it will permit surgery with more accuracy, speed, dexterity, and safety than imaginable today.