Accurate real-time depth control for CP-SSOCT distal sensor based handheld microsurgery tools

Abstract

This paper presents a novel intuitive targeting and tracking scheme that utilizes a common-path swept source optical coherence tomography (CP-SSOCT) distal sensor integrated handheld microsurgical tool. To achieve micron-order precision control, a reliable and accurate OCT distal sensing method is required; simultaneously, a prediction algorithm is necessary to compensate for the system delay associated with the computational, mechanical and electronic latencies. Due to the multilayered structure of retina, it is necessary to develop effective surface detection methods rather than simple peak detection. To achieve this, a shifted cross-correlation method is applied for surface detection in order to increase robustness and accuracy in distal sensing. A predictor based on Kalman filter was implemented for more precise motion compensation. The performance was first evaluated using an established dry phantom consisting of stacked cellophane tape. This was followed by evaluation in an ex-vivo bovine retina model to assess system accuracy and precision. The results demonstrate highly accurate depth targeting with less than 5 μm RMSE depth locking.

Review of intraoperative optical coherence tomography: technology and applications [Invited]

“…The Kang group at Johns Hopkins University demonstrated that Ascans could be acquired adjacent to the tooltip by mounting a fiber-optic common-path (CP) OCT probe along [107,108] or within [109][110][111] the shafts of forceps and needles for vitreoretinal surgery (Fig. 3(a)).…”

“…The reference interference signal was obtained from the partial back-reflection at the distal surface of the CPOCT probe, and the lack of an optical scanning mechanism resulted in a relatively simple and affordable optical design that could potentially be made as a disposable product. In its most recent iteration [108], the probe used a 100 kHz swept-source with a 1060 nm central wavelength, and M-scan images could be acquired and processed with GPU-accelerated software. The OCT probe was primarily used as a single-point axial ranger with micrometer-scale resolution to quantify hand tremor [111] and drive active motion cancellation systems [107,108,110], and to provide ranging feedback for a cooperative robotic surgery platform [109] (discussed in detail in Section 5.2).…”

“…In its most recent iteration [108], the probe used a 100 kHz swept-source with a 1060 nm central wavelength, and M-scan images could be acquired and processed with GPU-accelerated software. The OCT probe was primarily used as a single-point axial ranger with micrometer-scale resolution to quantify hand tremor [111] and drive active motion cancellation systems [107,108,110], and to provide ranging feedback for a cooperative robotic surgery platform [109] (discussed in detail in Section 5.2). The Joos group at Vanderbilt University incorporated a needle-based OCT probe [105] capable of Bscan imaging into the shaft of 23-gauge surgical forceps [112] (Fig.…”

“…10). In contrast to the master-slave system, other studies explored the utility of OCT-guided cooperative robots, in which the surgeon controlled the robot with their hand instead of a haptic device [107][108][109][110][111]. These robots utilized OCT integrated into the surgical instruments to provide closed loop feedback for applications such as tremor reduction or tool depth locking.…”

“…Automatic edge detection on the A-scan data allowed the researchers to estimate both hand tremor and the instrument distance to a surface, data which then fed a PID controller that drove the piezoelectric motors for automatic motion compensation. Cheon et al [108] used a more sophisticated real-time surface detection algorithm compatible with layered structures such as retina. This system performed depth locking by using spatially shifted cross-correlation of A-scans to determine the position error of the tip.…”