By Loris Fichera
When we think about robotic laser control, the first image that probably comes to mind is that of a machine that provides precise laser aiming, either through deflecting mirrors or other motorized optical devices. My team at Worcester Polytechnic Institute (WPI) is striving to build robots that can regulate not only laser aiming but also the physical interactions between the laser and human tissue. The knowledge of laser surgeons will be required to provide the level of control needed for safe laser-tissue interactions as this technology progresses.
Temperature must be controlled in many therapeutic applications of lasers. At WPI, we are equipping our robots with thermal sensors, more specifically, miniaturized infrared thermal cameras. And we are developing control algorithms that automatically regulate the laser output (intensity, spot, size, etc.) to achieve prescribed heating profiles.
We hope to help prevent thermal injuries that may occur as a result of accidental laser overexposure, such as carbonization. What makes carbonization difficult to prevent for a human laser operator is that the visual cues associated with it — namely, blackening of the tissue — only become visible once the damage has already occurred. Robots, on the other hand, can monitor tissue temperature in real time, and therefore can automatically cut off the laser output.
Historically, robotic automation has been used to replace human workers in jobs that are repetitive and/or dangerous. This is not what we are trying to accomplish with our work.
The surgical team must make an appropriate selection of laser treatment parameters for each procedure. There is inherent variability in how biological tissue absorbs laser light. Laser parameters that work well for one patient may not be suitable for another. My team recently conceptualized a laser control algorithm that can achieve consistent, repeatable heating. To validate the algorithm, we conducted experiments where a robotic arm controlled a carbon dioxide laser to thermally treat different types of tissue. Our work is currently at a proof-of-concept stage. But we cannot just bring a robot to an operating room and ask our clinical collaborators to perform surgery with it.
I believe we should involve clinical collaborators as early as possible in the design of surgical robotic technology. Historically, robotic automation has been used across multiple industries to replace human workers in jobs that are repetitive and/or dangerous. This is not what we are trying to accomplish with our work. Surgeons are among the most highly trained individuals in our society. When I work with laser surgeons, I normally seek input on the clinical end point that they wish to achieve, such as coagulation or vaporization. I also typically ask how they would approach a specific problem. In my experience, surgeons can think of clever solutions that would not necessarily cross an engineer’s mind. As we build toward instrumentation that will be functional in the operating room, these conversations will be vital to integrate the capabilities that they need to keep their patients healthy and safe.
Meet the author
Loris Fichera is an associate professor of robotics at Worcester Polytechnic Institute (WPI). He received a Ph.D. in robotics from the University of Genoa, Italy. Dr. Fichera has received the National Science Foundation CAREER Award, and the Young Investigator Award of the International Society for Computer-Aided Surgery (ISCAS); email: lfichera@wpi.edu.
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