Optimizing light delivery to perform teleoperative photoacoustic-guided hysterectomy

When designing an imaging system to perform photoacoustic-guided hysterectomy, one approach to achieve direct illumination of an imaging target is to attach optical fibers to the surgical tool. However, light blockage by the tool could potentially limit effectiveness. The work herein investigates optimal light delivery for a da Vinci surgical scissor tool. A tool tip located above a tissue surface was modeled with Monte Carlo simulations, and the resulting fluence was measured at the underlying tissue surface and 1 mm below the tissue surface. A design was prototyped and built based on the simulation results, and the corresponding light profiles were compared to theoretical calculations based on optical parameters and geometry. The simulated fluence measurements located 1 mm below the tissue surface were maximized with an optical fiber directing light 15° toward the tool shaft at a 12.7 mm separation distance between the fiber and the tool shaft, offering 29-48% improvement relative to 0° skew and 0.2 mm tool shaft-to-fiber separation distance, as a function of tool tip-to-tissue surface distances of 0-17 mm. After thresholding the simulated fluence at the illumination surface by 1/e of its maximum value, the simulated light profiles had similar shapes to the corresponding experimental profiles, demonstrating a reduction in the shadow caused by light blockage observed with the optimal design (relative to that achieved with the original design). The outer diameters of the 1/e thresholded simulated light profile and the corresponding theoretical surface profile agreed within 6-7%. These findings are promising to maximize light delivery in both robotic and nonrobotic photoacoustic-guided hysterectomies (as well as other surgeries that utilize minimally invasive tools), which has the potential to provide surgeons with more precise situational awareness.