Gary Boas, News Editor, firstname.lastname@example.org
CO2 lasers have become a common cutting tool in laryngology. They
offer submillimeter cutting precision, which is especially important because many
lesions sit on the vocal cords. An error in cutting can potentially cause scarring
and irreversible damage to the patient’s vocal function. The lasers also keep
to a minimum thermal damage during cutting and the closing up of blood vessels.
Thus, surgeons can both cut and coagulate at the same time, allowing resection of
lesions in a bloodless, easily viewable field.
Until recently, though, these lasers had no fiber
delivery system. Surgeons had to insert a rigid instrument, known as a laryngoscope,
into patients’ mouths to create a line of sight between the laser and the
lesions. This did not work well in all settings. Sometimes surgeons had trouble
exposing the larynx in patients who were obese or who had short necks.
The problem of delivering CO2 laser
light through the mouth was especially vexing to Dr. Marshall M. Strome, chairman
of the Cleveland Clinic Head and Neck Institute. He wanted to use a robot developed
for other medical applications for head and neck surgeries. The robot could provide
vastly improved precision and flexibility, but he needed articulated arms with mirrors
and prisms to transmit CO2 lasers. These were incompatible with the robot.
Then someone suggested that he take
a look at a new technology from Cambridge, Mass.-based OmniGuide Inc. —
a hollow-core optical fiber that can flexibly guide a CO2 laser beam. Attaching
the fiber to the robotic arm could enable laser-assisted robotic surgery for head
and neck applications.
A hollow-core optical fiber that can guide
a CO2 laser beam improves flexibility and precision of surgery of the throat. However,
because of the combinations of materials used, the developers of the technology
had to devise a way to pull the fiber over long lengths while maintaining uniform
The technology grew out of work conducted
by Yoel Fink, now associate professor of materials science at MIT, also in Cambridge.
For his doctoral dissertation, Fink designed a “perfect” mirror based
on a dielectric stack of alternating high- and low-refractive-index materials. The
original idea was reported in Science in 1998. Fink and others formed OmniGuide
in 2000, and in 2002, they published a letter in Nature describing use of
the technology to deliver CO2 lasers through hollow-core fibers.
Confinement of light is achieved by
alternating submicron-thick layers of high-refractive-index glass and low-refractive-index
polymer, they explained, creating large photonic bandgaps and leading to ultralow
losses. Still, they needed to develop a manufacturing method.
At first, they employed the technique
commonly used to make telecommunications fibers — pulling fiber from a preform.
However, this can be challenging when the fiber contains a combination of materials
in its core. The high- and low-refractive-index materials used in the mirror have
different optical properties and, consequently, may have different mechanical and
thermal properties, which can cause difficulties when pulling the fibers. Ultimately,
the research group at MIT and at OmniGuide devised proprietary scalable ways to
draw the fibers over very long lengths while maintaining a uniform layer thickness
on the submicron scale.
The company worked with Strome to attach
the hollow-core fibers to a robotic system made by Intuitive Surgical Inc. of
Sunnyvale, Calif., enabling delivery of CO2 laser light through the mouth without
the laryngoscope. The system consists of a surgeon’s console, a cart with
four interactive robotic arms, a three-dimensional vision system that is based on
two cameras situated near the mouth, and instruments designed with 7° of motion
to mimic the movements of the surgeon’s hand and wrist. The instruments
are assigned specific surgical tasks, including clamping, suturing and tissue manipulation.
The robot allows more flexibility and
precision than is possible when performing procedures manually. For example, it
enables the surgeon to make circumferential cuts. “You can get to the bottom
of the tumor and take it out much more readily,” Strome said.
He recently used the setup to perform
laser-assisted robotic surgery at the clinic on a patient with a massive cancerous
tumor involving the larynx and pharynx. He removed the tumor in about four hours,
avoiding an invasive open procedure and saving more than two hours of operating-room
time. The patient reported less pain than prior to the surgery just two days later
and could swallow again within a week.
The combination of the robot and CO2 laser light delivered via the hollow-core optical fiber provides much higher precision than could be achieved otherwise, Strome said, enabling tremendous potential for
head and neck surgeries. Indeed, he plans to use it for resection of a tongue-based
tumor. It could contribute to even more significant advances in the next five years,
as the robots become smaller and more manageable. Moreover, the ability to control
the robot remotely means that, in the future, a surgeon could sit at a console and
operate on someone in another country, Strome added. This could open up a number
of markets in areas that lack adequately trained doctors.
The fiber technology incorporates a “perfect” mirror that is based on a
dielectric stack of alternating high- and low-refractive-index materials to create
large photonic bandgaps, enabling ultralow losses.
Ultimately, he would like the manufacturer
of the robot to integrate the fiber technology into the instrumentation. Currently,
he attaches the fiber to the robot via a sheath with a hook. “It would be
very nice to develop an arm with a channel in it that the laser could go through,”
Contact: Dr. Marshall M. Strome, Cleveland Clinic Head and Neck Institute, Cleveland; +1 (216) 444-6686. Gil Shapira, OmniGuide Inc.; e-mail: email@example.com.