Biomedical Engineering Reference
In-Depth Information
Figure 4
. Pretreatment and 6-month-posttreatment coronal MR images of a patient treated
with staged CyberKnife radiosurgery.
time, several developers are working to adapt this technology to perspective
volume rendering of three-dimensional image sets. The goal is to use these
modes of rendering virtual reality, with both partial and total immersion, for
actual surgical navigation as well as simulation (for modeling and simulation of
brain tumors, see, e.g., this volume, Part III, chapter 6.3, by Mansury and Deis-
boeck). A current problem in using these systems during actual surgery is the
inability to comfortably track the movement of a surgeon's head and eyes and to
adjust the simulated image position. Presently available heads-up helmets and
eyeglass designs are uncomfortable after a prolonged period of usage. However,
using large high-resolution projection or flat video screens may eliminate the
necessity for cumbersome head tracking, as these large screens can encompass
both the central and peripheral visual fields and provide the surgeon with a com-
fortable mode of virtual reality through partial immersion (24).
3.3. Haptics
Another area that is a work in progress involves methods for simulating the
surgeon's sense of touch. Surgeons depend on tactile feedback from the body
tissues they are manipulating during a surgical procedure. All tissues have vary-
ing degrees of rigidity, elasticity, tensile strength, and deformability (see also
this volume, Part IV, chapter 4, by Kaazempur-Mofrad, Weinberg, Borenstein,
and Vacanti). A surgeon's innate and conscious sense of these tissue conditions
through touch with a gloved finger or indirectly through surgical instruments is a
key factor in the precision by which different tissues are separated to create cor-
