Surgery assisted by magnetic resonance imaging has one drawback ? surgical steel does not react well to electromagnets.
Now engineers at Johns Hopkins Medicine have an answer. A completely nonmagnetic robot driven by air and light can conduct biopsies with more precision than a surgeon?s hand.
“It?s the tool for the future, really,” said Dr. Danny Song, a surgical oncologist with Hopkins.
The motor, which runs without metal or electricity, can safely power remote-controlled robotic medical devices used for cancer biopsies and therapies guided by magnetic resonance imaging.
A description of the new motor, made entirely out of plastics, ceramics and rubber, was published in the February issue of the IEEE/ASME Transactions on Mechanotronics. Dubbed PneuStep, the motor consists of three pistons connected to a series of gears. The gears are turned by airflow, controlled by a computer located in an adjacent room.
“Molecular imaging can define where the cancer is and where it is not within the prostate,” Song said.
Prostate biopsies in particular present a challenge because X-ray and other forms of imaging do not provide a clear enough picture for surgeons, who often must operate “blind,” he said.
“Prostate cancer is tricky because it only can be seen under MRI, and in early stages it can be quite small and easy to miss,” said Dan Stoianovici, Ph.D., an associate professor of urology at Johns Hopkins and director of the robotics lab in a statement. “This should increase accuracy in locating and collecting tissue samples, reduce diagnostic errors and also improve therapy.”
Stoianovici?s team used six of the motors to power the first-ever MRI-compatible robot to access the prostate gland. The robot currently is undergoing preclinical testing.
The robot moves alongside the patient into the MRI scanner and is controlled remotely by observing scanned images. Fiber optics feed information back to the computer in real time for guidance and readjustment.
“The robot moves slowly but precisely, and our experiments show that the needle always comes within a millimeter of the target,” Stoianovici said.
