Biomedical Engineering Reference
In-Depth Information
The Accuray (Sunnyvale, CA) CyberKnife, invented at Stanford University,
mates a lightweight linear accelerator with a six-degree-of-freedom movement
industrial robot (1,9). This increased range allows radiation beams to be posi-
tioned in an infinite number of positions around a target. Using inverse planning
algorithms, the surgeon can now generate a non-isocentric collection of beam
paths that provides a focused dose of radiation which is highly conformal to the
three-dimensional shape of a target volume, yet has rapid fall-off, so that sur-
rounding tissue is protected from radiation damage. Additionally, the Cyber-
Knife system uses stereotactic radiographic image tracking to monitor target
volume motion and has the capability of adjusting the beam trajectories in a few
seconds if the patient moves during treatment. This system is used routinely for
radiosurgical treatment of lesions of the cranium and spinal column. It has re-
cently been coupled with optical digitizers to track chest-wall and abdominal-
wall movement so that moving target volumes in organs such as the lung and
pancreas can also be treated with radiosurgery (Figures 3 and 4).
2.4.3. Robotic Micromanipulators
While neurosurgeons focused on efficient systems for use within the unique
parameters of the brain, other medical specialists were developing robotic
micromanipulators. These manipulators not only enhance the surgeon's manual
dexterity, but also allow indirect visualization through endoscopic ports, thereby
permitting operations through smaller openings than were previously possible.
This development soon led to designs for manual robotic manipulation of stan-
dard surgical tools coupled with remote vision, allowing certain surgeries to be
performed remotely. Communication between the site where the surgeon is ma-
nipulating the remote tools and the actual surgical site can be accomplished ei-
ther by direct wiring or long-distance broadband radio waves.
Systems are now commercially available that use telepresence hand ma-
nipulators to permit remote manipulation for inserting instruments through en-
doscopic channels. Such systems are manufactured by Intuitive Surgical
(Mountain View, CA) and Computer Motion (Goleta, CA) and are starting to be
used by cardiac surgeons (3,4). These systems have a unique method for ma-
nipulating a forceps, with simulated wrist movements that are moved deep into
the operative field, thus permitting dissection and more complex surgical ma-
neuvers such as suturing to be performed through small access ports and at
depth. This capability has been applied to coronary artery bypass. Similar minia-
turized systems are being developed for neurosurgical procedures.
3.
THE FUTURE
3.1. Teleremote Surgery
With appropriate wired and wireless computer communication, robotic sys-
tems similar to the telepresence systems have been developed so that a surgeon