Advances in robotics technology are completely transforming today’s hospital operating rooms. With robot control and assistance, surgery for any kind of injury or ailment is faster, more accurate, and less invasive than ever before. Because robots help accelerate procedures, operations become safer. With conventional surgery, a surgeon performing an operation lasting several hours can become exhausted. As a result, the surgeon’s hand can be subject to harmful errors, particularly for complicated and delicate tasks like neurosurgeries. But a robot hand never tires, and it won’t waver out of position.
Improvements in sensing (particularly haptic sensing), imaging, better robotic control and articulation, and the development of robots that are more dexterous have spurred the dramatic rise in robotic surgery. The medical community is now developing a greater understanding of its benefits as well as the processes involved in ensuring seamless interfacing between a surgeon and a robotic system.
Medical robots aren’t completely autonomous, and they don’t perform the surgery by themselves. Instead, they assist the surgeon, who commands and controls them. As a result, surgery is fast becoming a partnership between man and machine. According to BCC Research, the market for surgical robots in the U.S. alone will total $2.5 billion by 2011. This market is projected to grow between 2006 and 2011 by an expected annual growth rate of 43%.
Medical robots are assisting in urological, neurological, gynecological, cardiac, orthopedic, gastrointestinal, pediatric, and radio-surgical procedures. Depending on the degree of the surgeon’s interaction during an operation, these systems can be broadly divided into three categories: supervisory-controlled, telesurgical, and shared-control systems.
During supervisor-controlled surgeries, the robot executes the procedure in response to programmed computer inputs from the surgeon. In telesurgery (or remote surgery), the surgeon manipulates the robot’s hand from a distance using real-time imaging and haptic feedback. Surgeons are most involved in shared-control procedures, where they use the robot to obtain “steady hand” manipulation of the surgical instruments in use.
The U.S. government also is pursuing robotic surgery. The Trauma Pod program from the Defense Advanced Research Projects Agency (DARPA) envisions the operating room of the future. Led by SRI, this multiphased program seeks to use robotics to project the skills of surgeons to precisely where they’re needed on the battlefield (Fig. 1). It includes contributions from the universities of Washington, Texas, and Maryland; Oak Ridge National Laboratory; General Dynamics; Intuitive Surgical; General Electric; Integrated Medical Systems; and Robotic Surgical Tech.
The most notable product on the market, the da Vinci Surgical System from Intuitive Surgical Co., consists of a viewing and control console and a surgical arm unit (Fig. 2). Used worldwide, it’s the only robotic-assisted device being used for laproscopic as well as a variety of minimally invasive keyhole surgeries. It’s also been used successfully in a number of gynecological, urological, and cardiac procedures.
PRE-PLANNING WITH VIRTUAL SURGERIES
For all its advantages, robotic surgery still needs better computer modeling, image processing, and haptic sensing for a more seamless integration of man and machine in surgical operations. Such improvements will enable better pre-surgical planning, too, allowing doctors to perform virtual surgeries before the actual operation.
The University of Washington is developing a “holomer” system that serves as a total body scan to guide intra-operative navigation during surgery. A surgeon can then use this information to perform a virtual operation on a patient prior to performing the real operation.
That’s also the goal at the Johns Hopkins University Engineering Research Center for Computer Integrated Systems and Technology. Its surgical CAD-CAM system offers “one-stop shopping” to integrate re-planning through post-operation evaluation and to create modular systems for “plug-and-play” surgery (Fig. 3).
The researchers also are investigating the sense of touch, which is very important in delicate surgeries. “Surgeons have asked for this kind of feedback. So we’re using our understanding of haptic technology to try to give surgeons back the sense of touch they lose when they use robotic medical tools,” says Allison Okamura, a leading researcher in man-machine interaction at Johns Hopkins.
Sensors could be attached to the robotic tools to convey how much force is being applied to, say, a surgical suture. Also, mathematical models would represent the moves made by the robotic tools, and this data would be converted to haptic feedback sent to the surgeon.
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Okamura’s team developed a visual haptics system that sends haptic information observed by a surgeon on a display during suturing. A colored circle follows the image of the suturing tool, with red showing too much force (where a suture might snap) and green and yellow indicating just the right amount of suture force.
Researchers at Tufts University are also investigating methods of simulating minimally invasive surgery that uses visualization coupled with haptics to incorporate feedback into robotic surgical training. They’re concentrating on developing tools for laproscopic surgery using a video camera and force-feedback sensors.
“In teleoperation, force feedback or haptic feedback is very important,” says Caroline Cao, assistant professor of mechanical engineering at Tufts. “Otherwise, you don’t feel what it is that you’re dealing with. You end up either colliding into your targets or you don’t know how to control the forces in order to manipulate your target.”
THE IMPORTANCE OF VISION SENSING
With vision-sensing platforms, surgical robots see where a procedure is being used as well as how precisely that procedure is being performed. These platforms are essential to bringing accurate and affordable robotic surgery to the market. One company, Prosurgics, is collaborating with Adept Technology to produce next-generation surgical robotic systems.
“This collaboration will combine our expertise in robotics for image-guided and navigated neurological and soft-tissue surgery with those of Adept Technology in robotic control and vision-guided applications to provide affordable surgical robotic products for improved patient care and optimized economies for healthcare providers,” says Colin Robertson, Prosurgics’ business development marketing director.
“Our experience in image-guided robotics is very broad and strong. This includes the assembly and manufacturing of mobile phones, computer disk drives, solar cells, and food handling. It will provide valuable assistance to the medical robotics field,” adds Dave Pap Rocki, Adept Technology’s chief technology officer.
Prosurgics offers advanced surgical tools like the PathFinder, an image-guided manipulator for precise localization in neurosurgical procedures (Fig. 4). With this technology, surgeons can position stereotactic instruments to within an accuracy of 1 mm. The firm additionally makes the EndoAssist, an image-guided manipulator for endoscopes that’s used in minimally invasive thoracic and abdominal surgeries.
ROBOTIC ORTHOPEDICS ON THE MOVE
Image-guided orthopedic robotic surgeries represent one of the fastest growing medical areas. Approximately 400,000 people each year have knee-replacement surgery, which generally requires lengthy surgical incisions and can cause a considerable amount of pain. Moreover, patients face lengthy recovery times before they’re on their feet. This is changing, though, with robotic orthopedic procedures that require shorter incisions, are less painful, and allow for much faster recovery times.
A study involving engineers and surgeons from the Imperial College of London shows that robotic assistance improves accuracy in knee surgery, leading to knee replacements that function better and last longer than conventional surgical techniques. The study was funded by the Acrobot Co. Ltd., a spin-out of the Imperial College of London.
One prominent procedure is MAKOplasty knee resurfacing from Mako Surgical Corp. Its tactile guidance system (TGS) allows surgeons to accurately plan the size of the knee implant and optimize the implant’s position and orientation, relative to a CT scan taken before surgery.
The Robodoc surgical assistant system from Integrated Surgical Systems also supports image-guided orthopedic surgery. It integrates the company’s Orthodoc Presurgical Planner with a computer-controlled robot for jointreplacement surgeries. It can also be used for neurosurgical procedures.
The German Federal Ministry of Education and Research is funding orthoMIT, a “Gentle Surgery by Innovative Technology” project known as SOMIT. It aims to develop an intelligent platform for gentle operative therapy in robotic orthopedic and traumatology procedures, particularly hip, knee, and spinal-column surgery.
Robotic radiosurgery has also been shown as an excellent alternative treatment for tumors. The Cyber Knife from Accuray and the Gamma Knife from Elekta use highly precise beams of radiation to destroy tumors quickly, painlessly, and without downtime or lengthy hospital stays. Tumors anywhere in the body can be treated, even those previously considered untreatable. Using CT images, these tools enable surgeons to construct a very precise pre-surgical plan to deliver a total dose of radiation to the tumor while minimally exposing the surrounding normal tissues.
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MORE AGILE AND SMARTER TOOLS TO COME
Minimally invasive “keyhole-like” robotic surgeries will continue to make strides with even greater agility. The payoff will be shorter patient hospital stays, more accurate and effective procedures, and lower risks (e.g., infections) thanks to smaller surgical openings and faster procedures. For example, Japan’s Tokyo Institute of Technology is investigating an approach that allows the assembly of robotic components within the body, prior to surgery, to assist in robotic surgeries on large and slippery internal organs like the liver.
These researchers are developing a three-fingered steel hand, with each finger 5 cm long, for grasping internal organs. They’re using a hollow arm, 30 cm long and 16 mm in diameter, that’s inserted into the body via a small incision. The three fingers are then passed part of the way through a nearby keyhole and then snapped into place on the arm. Stiff wires along the arm allow the fingers to grasp organs. Experiments inside a dummy body cavity have shown this approach to be effective.
At Johns Hopkins University, researchers hope to soon unveil advanced robotic grippers and retractors with force sensors for human trial runs. These tools will allow surgeons to avoid gripping blood vessels too tightly. Additionally, they will allow oxygen sensors to differentiate diseased tissue from healthy tissue. One tool flexes much like an elephant trunk to glide down a patient’s throat for scar-less repairs of the upper airways. Another tool that’s now under development will let surgeons bust eye clots inside minuscule blood vessels.
Robotic snake-like tools are under development at the Imperial College of London and Carnegie Mellon University. The Imperial College’s i-Snake project, a $4.2 million program funded by the Wellcome Trust, a large U.K. charity that funds innovative biomedical research, centers on a flexible robotic arm that acts as a surgeon’s hands and eyes. The technology will permit surgeons to navigate difficult and restrictive regions of the body, such as the alimentary tract and cardiovascular pathways, faster and more precisely than they could while using conventional techniques.
Carnegie Mellon’s miniature HeartLander facilitates minimally invasive therapy on the surface of the beating heart (Fig. 5). Under physician control, the robot enters the chest through an incision below the sternum and adheres to the epicardial surface of the heart. It then autonomously navigates to the specified location and administers the treatment. Compared with existing approaches, it improves the precision and stability of interaction with the heart’s surface while decreasing the morbidity associated with access.
One of the greatest challenges lies in developing a robotic system that works in a magnetic-resonance imaging (MRI) environment where surgery is being performed. MRIs have strong and sensitive magnetic fields that must be bypassed. Otherwise, the MRI image will be distorted. The Johns Hopkins PneuStep, a robotic tool that’s designed for prostate surgery, alleviates these MRI problems.
PneuStep consists of six motors that power an MRI-compatible robot. Three pistons are connected to a series of gears. The gears are turned by air flow, which is in turn controlled by a computer located in a room adjacent to the MRI machine. The system can achieve precise and smooth motion up to 50 µm, finer than a human hair and well above that of a human surgeon. PneuStep is currently undergoing preclinical trials.
The neuroArm is another MRI-compatible robotic tool being developed at Canada’s University of Calgary. This machine can provide precision motions up to 25 µm. It uses lead-zirconium-titanate (PZT) motors to move a small ceramic finger back and forth. The finger rotates a ceramic ring, creating motion through friction.
In the near term, cost will limit the widespread adoption of full-fledged large robotic surgical systems, which can go for $1 million or more and are expensive to maintain. Yet studies reveal that most surgeons who used such systems have become converts to this technology. Clearly, lower-cost systems are needed, and many researchers worldwide are busy working to reach that goal.