New results with the Smart Tissue Autonomous Robot (STAR)
"In a recent set of experiments, STAR’s inventors showed that it makes
more precise cuts than expert surgeons, and damages less of the
surrounding flesh. The researchers presented their results at the recent robotics conference IROS 2017.
“I really believe that this is the future of surgery,” says study coauthor Axel Krieger, an assistant professor of mechanical engineering at the University of Maryland.
“I believe this will come about first for small sub-functions of surgery and get more and more complex,” Krieger tells IEEE Spectrum,
“similarly to autonomous cars, where small features such as
brake-assist slowly morphed into more and more autonomy. I absolutely
would trust a robot like that for my surgery, once it is fully developed
and validated.”...
For the current study, the researchers went to a butchershop and
purchased three varieties of pig tissue: skin, fat, and muscle. Before
they tested the system against human surgeons, STAR first had to prove its ability to make precise cuts in these three types of irregular soft tissue, which can resist a cutting tool and then give way abruptly,
causing the tool to make inaccurate cuts.
For this visual tracking, the robot relies on tiny marks that the
researchers place on the tissue beforehand, which show up on its
near-infrared camera. The researchers therefore call STAR a
semi-autonomous robot. “After registering the markers, the robot
autonomously performs the tumor cutting,” Krieger says.
Having proved that the system can competently cut, Krieger and his
colleagues had STAR go head-to-head with expert surgeons on a cutting
task in pig skin.
Both the robot and the surgeons were asked to cut a straight
5-centimeter line. Because surgeons are trained to cut tissue between
known landmarks rather than to cut absolute distances, reference lines
were drawn on the skin. Some of the surgeons made the cuts in an open
surgery setup while others had a laparoscopic setup, the increasingly common surgical practice in which tools are inserted through a tiny hole.
Both the robot and the humans were judged based on how much they
deviated from the ideal cut line of the desired length, as well as how
much char (damaged flesh) surrounded the incision. The results: STAR’s
cuts were closer in length to 5 centimeters, they deviated less from the
ideal cut line, and they resulted in less char.
In the final stage of the experiment, the researchers had STAR
cut a fake tumor (made of clay) out of a piece of pig fat; a thin piece
of tissue was placed above the fake tumor to make it harder for the
robot to see its target. The researchers placed markers around the fake
tumor’s edges and instructed STAR to cut out the tumor with a
4-millimeter margin on all sides. Again, the robot performed its cuts
with great accuracy that would bode well for a cancer patient under its
care.
Krieger says the next step is to train STAR to deal with tumors
that have complex 3D shapes, which will require new cameras for visual
tracking and more sophisticated surgical planning software.
In the paper, the researchers say the robot has real clinical
potential. Today, surgeons often mark a tumor’s edges with ink, but they
could easily switch to the infrared markers that would allow the robot
to go to work. If physicians want to make STAR fully autonomous, the
robot could draw information about the tumor’s location from a CT or MRI
scan. Then the robot would be fully equipped to be the star of the OR."
Source: IEEE Spectrum
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