Page 438 - Biomedical Engineering and Design Handbook Volume 2, Applications

416 SURGERY

FIGURE 14.17 Augmented reality CIS system for brain tumor surgery. The tumor image (round area) and brain structure
(below tumor image) are projected directly on the patient’s skull. (Photo courtesy of Ron Kikinis.)

replace an actual exploration on the patient with a virtual exploration on MRI images. A three-
dimensional reconstruction of the anatomical structures of interest, typically tubelike, is constructed
from the data set, and a fly-through inspection path inside the structure is computed. The clinician is
then presented with a virtual movie that simulates the actual endoscopic exploration (Fig. 14.18). On
the basis of these images, the clinician can look for and identify certain pathologies, such as tumors,
and then determine if an actual examination or surgery is necessary. Several algorithms have been
developed for model construction, fast visualization, and computation of fly-through path. 98

14.4.2 Robotic Systems for Precise Preoperative Plan Execution
One of the drawbacks of navigation systems is that they cannot guarantee that a planned surgical ges-
ture, such as screw placement or needle insertion, will be executed precisely as planned. To ensure
not only precise positioning but also precise execution, surgical robots have been developed. We
describe next two examples of the most common types of active surgical robots: the ROBODOC system
discussed earlier and the LARS robot for percutaneous therapy.

Robotic Orthopedic Surgery. Because bone is rigid and relatively easy to image in CT, and
because geometric precision is often an important consideration in orthopedic surgical procedures,
orthopedic surgery has been an important domain for the development of CIS systems. For
example, the ROBODOC system has been in clinical use since 1992 and combines CT-based
preoperative planning with robotic machining of bone. Both ROBODOC and a very similar sub-
sequently introduced system called CASPAR ®99 have been applied to knee surgery 100–102 as
well as hip surgery. Other robotic systems have been proposed or (in a few cases) applied for
hip or knee surgery. 38,39,103–107