Lower cost, portable surgical robots could be smooth operators

West Lafayette 02 March 2006A mechanical engineer at Purdue University is teaming up with medical doctors in research aimed at developing less expensive, portable and versatile surgical robots that could become more common in operating rooms. The researchers also are trying to incorporate tactile sensors into the robots to enable surgeons to feel tissue and better diagnose medical conditions.


"Robots don't perform the surgeries, but they are tools that give the surgeon more dexterity", stated William Peine, an assistant professor of mechanical engineering. "They let you get into confined spaces. You can eliminate hand tremor, and you can be very precise and delicate. It's as if the tips of the instruments become your fingertips."

Current robots are complex and often require a large operating room and extra set-up time. The researchers are trying to develop a new breed of surgical robot that is smaller and easier to use and can be set up in less time. This would give surgeons the option of deciding to use a robot on the fly if necessary, according to William Peine.

"Conventional surgical robots are the equivalent of a sophisticated racecar compared to your basic family sedan", he stated. "For some surgeries, you need a complex robot, but for many surgeries you do not. You wouldn't take an Indy racecar to the grocery store. What you really want is a hand tool that has robotic capability so that a surgeon could be in the middle of a procedure and be able to bring in the robot."

William Peine, an assistant professor of mechanical engineering at Purdue, operates hand controls for a surgical robot under development. The system is designed to give surgeons the dexterity they will need for operations by mimicking the human wrist in providing "seven degrees of freedom", or roll, pitch and yaw. The system also provides the ability to control gripping instruments placed inside the body, enabling the robot to reproduce the motion capabilities of the human hand on a smaller scale, allowing for more precise control in confined spaces. A small camera provides a magnified view of the robotic probes in action, and a real-time picture is displayed on a monitor mounted on the surgeon's console. Photograph by courtesy of Purdue News Service photo/David Umberger.

A key innovation that is ideal for robotic surgery is a technique in which doctors insert thin probes called laparoscopic instruments into the body through small openings, eliminating the need to make large incisions that leave scars and require a lengthy recovery time, William Peine stated.

Without robots, surgeons manipulate the laparoscopic probes with a handle that remains outside the body. Using such handheld tools presents challenges to surgeons because it is difficult to manipulate the devices. For example, moving the handle in one direction causes the probe to move in the opposite direction inside the body.

"They call this the fulcrum effect", William Peine stated. "If I move the handle up, the tip moves down inside the body. If I move it down, it moves up, left and right are reversed. But a robot can understand all the mechanics and compensate for them, eliminating the fulcrum effect."

Robots also can be used to increase dexterity, which has proved to be crucial in prostate cancer surgeries because inadvertently removing or damaging nerves located near the prostate gland can result in incontinence and impotence. "The robot can reach into the area very precisely and avoid those nerves", William Peine stated.

During robotic surgeries, the surgeon sits at a console and uses hand controls to direct robotic arms that move the probes, and a camera lets the surgeon see inside the body during the operation. The camera magnifies the view on a computer screen mounted on the console.

Today's surgical robots use the same probes several times before they are replaced with new probes. William Peine is collaborating with surgeons at the Indiana University School of Medicine in work aimed at developing less expensive systems that might use disposable probes to reduce costs.

"It's a collaboration between technology and surgery, where we hope to use our combined expertise to develop systems for the benefit of patients", stated Dr. Chandru Sundaram, a surgeon and associate professor at the Indiana University School of Medicine's Department of Urology, located at Indiana University-Purdue University Indianapolis.

"Over the years, I have used every surgical robot that has been clinically available", stated Dr. Sundaram, who is director of the department's minimally invasive urology programme. "None of these would be considered truly robots because robot implies that it will perform a function totally on its own. They are really computer-assisted surgical devices that provide advantages such as greater accuracy, miniaturization of instruments, being able to operate laparoscopically, do reconstructive procedures and see with greater magnification and with better lighting."

The only surgical robot currently on the market costs about $1 million, but researchers are trying to create alternatives that cost about $250.000. In addition to developing less expensive, more portable robotics, William Peine and other researchers also want to create more sophisticated systems for a variety of surgical procedures, according to Dr. Sundaram.

"I think we have just touched the surface of robotic technologies for surgical assistance", he stated. "There is a huge amount of research and development that is going to happen in the future. The most complicated future roles will involve tactile feedback and image-guided surgery where you feed in information you have from CT scanners or ultrasounds or magnetic resonance imaging and the robot will accurately go to that particular part of the body and do whatever needs to be done."

One future application for robotic surgery might be endoluminal surgery, in which a light source is part of a flexible probe that could be snaked throughout the body, perhaps gaining entry through the stomach, an artery or some other part of the body.

"If you have cancer of the stomach, doctors would go in with the instrument and remove that area of tissue", William Peine stated. "Another possible application is fixing reflux disease. A new area that doctors are pursuing is trans-gastric surgery, where you go into the mouth, enter the stomach, make an incision in the stomach wall and then into the abdominal cavity. Once you are in the abdominal cavity, you can remove someone's gall bladder, for example. Because you gain entry through the mouth, there is no scar."

Taking endoluminal surgery a step further, surgeons want to use a technique called interventional radiology for robotic surgeries. "With interventional radiology, doctors will use real-time X-rays, called fluoroscopy, to see what the probe is doing inside the patient", William Peine stated. "Surgeons will be able to enter an artery near the groin area and navigate through arteries and into the heart, brain, to other major organs, snaking all through the venous system to perform surgeries in those areas of the body."

Doctors now use catheters in arteries to gain access to the heart and blood vessels. "They can inflate a balloon or insert a stent, but if you use a computer-controlled robot tip, you have the ability to manipulate tissue more carefully inside the heart, for example", William Peine stated. "So you might be able to repair a valve without needing open-heart surgery. Compare the two: open heart surgery, where you stop the heart, connect tubes, split the patient's sternum in half, or using a procedure where a catheter goes in and you are home the next day."

In the area of tactile sensors, researchers are working to create devices that can relay the sense of touch to surgeons, according to William Peine, who developed such a palpation instrument while he was a doctoral student at Harvard University.

"One drawback of minimally invasive surgery is that you can't get your fingers inside the patient to touch the tissue", he stated. "You can't palpate, and palpation is used extensively in medical procedures and in diagnosis. A surgeon may find an artery by sensing the pulsations, or locate a tumour by feeling it. A tactile sensor would measure the same sorts of things. You could use a device like this, for example, to find small lumps in the lung during surgery."

The sensor would relay information to a computer, where it would be displayed on a monitor as a colour-coded "tactile map" that tells a surgeon what the probe tip is feeling, William Peine stated.

William Peine, whose research involves creating both software and hardware for surgical robots, helped form a company called Pressure Profile Systems, located in California, which develops and markets tactile medical devices. He also is affiliated with Purdue's Regenstrief Center for Healthcare Engineering at Discovery Park, the university's hub for interdisciplinary research.

"The Regenstrief Center's mission statement is to design, implement and sustain interdisciplinary solutions to transform health care delivery systems", William Peine stated. "We emphasize that solutions and new technology should improve the quality, efficiency, safety and accessibility of health care. Surgical robotics have the potential to do this because less expensive robots reduce costs and make the technology available to more hospitals, while the quality and safety of care would improve by including a computer in the loop with the surgeon."

Leslie Versweyveld

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