Exploring Robot-Assisted Optical Coherence Elastography for Surgical Palpation

Optical Coherence Elastography (OCE) is a method that discerns local tissue stiffness using optical infor- mation. This method has recently been explored for laryngeal cancer tumor margin detection but has not been widely de- ployed clinically. Part of the challenge hindering such clinical deployment is the need for controlled high-precision mechanical probing of the tissue. This paper explores the concept of robot- assisted optical coherence elastography(OCE) and presents a preliminary system integration used to demonstrate the approach for stiffness mapping and discerning tumor margins. The approach is demonstrated on a custom Cartesian stage robot, and a custom-built OCE system comprised of an 830 nm broad-band laser with a vector-analysis method for phase gradient estimation and strain imaging. The paper illustrates one of the advantages of robot-controlled probing in terms of increasing the accuracy of the OCE system in a large range of displacement and strain. By leveraging motion information from the robot, online re-calibration of the OCE strain map may be achieved, thereby reducing OCE errors. After calibra- tion, it is shown that the error in estimating the local Young’s modulus is 0.485% in the silicon phantom and 0.531% in the agar phantom. These results suggest that future integration of optical coherence tomography(OCT) in clinically deployable robots may offer advantages in enabling local stiffness map estimation using OCE.