Page 432 - Biomedical Engineering and Design Handbook Volume 2, Applications

410 SURGERY

FIGURE 14.13 Robot system for use in open-magnet MRI system. 117

14.3.7 Human-Machine Interfaces

Computer-based systems that work cooperatively with humans must communicate with them, both
to provide information and to receive commands and guidance. As with surgical robots, surgical
human-machine interfaces (HMIs) have much in common with those for other application domains,
and they draw upon essentially the same technologies (speech, computer vision and graphics, haptics,
etc.) that have found use elsewhere. In many cases, HMI subsystems that have been developed for
other uses may be adapted with little change for surgical use. However, attention must be given to
the unusual requirements of surgical applications. 47 Surgeons tend to have very high expectations
about system responsiveness and transparency but have very low tolerance for interfaces that impede
their work. On the other hand, they can also be quite willing to put up with great inconvenience if
the system is really performing a useful function that truly extends their capabilities.
Surgeons overwhelmingly rely on vision as their dominant source of feedback during surgery.
Indeed, the explosion in minimal access surgery over the past decade has very largely been the result
of the availability of compact, high-resolution video cameras attached to endoscopic optics. In these
cases, the surgeon’s attention is naturally focused on a television monitor. In such cases, it is often
possible for the computer to add computer graphics, text, and other information to the video
stream. 48,49 Similarly, surgical navigation systems 8,9,45–52 provide computer graphic renderings and
feedback based on tracked surgical instrument positions and preoperative images. The so-called vir-
tual fluoroscopy systems 58–61 show predicted x-ray projections based on intraoperative fluoroscopic
images and tracked instrument positions. One very important challenge in the design of such sys-
tems is providing useful information about the imprecision of the system’s information, so that the
surgeon does not make decisions based on a false determination of the relative position of a surgical