Real-Time SLAM-Guided Closed-Loop Photodynamic Therapy with Pixel-Accurate Light-Dose Control

Abstract

Precise light-dose delivery is essential for photodynamic therapy (PDT), yet current handheld systems remain operator-dependent and lose accuracy under motion. We present a SLAM-guided, closed-loop control framework that enables co-temporal and co-spatial photodynamic diagnosis (PDD) and PDT with a single handheld endomicroscopic probe, while enforcing pixel-level dose control. The probe integrates a fiber bundle that shares a common optical path for both PDD and PDT and is paired with a digital micromirror device (DMD) for (mu)m-scale pattern projection. An extended Kalman filter fuses optical-tracking measurements with texture-limited endomicroscopic images at 30 Hz, providing robust six-degree-of-freedom pose estimates that expand the probe’s effective field of view and drive real-time pattern updates. A dose-map SLAM algorithm accumulates light dose over the reconstructed lesion surface during handheld scanning, while pixel-level dose control is enforced by referencing previously accumulated light at each location. Quantitative evaluation shows a spatial registration error between diagnostic and therapeutic systems within 5.2~mathrm{mu m}. Experiments on fluorescence phantoms achieved sub-millimeter localization accuracy ((0.3~mathrm{mm}) RMSE), significantly outperforming vision-only and tracker-only baselines. Finally, tests on targets with quadrant-specific dose limits confirmed SLAM-based dose control, achieving dose uniformity within pm 0.186~mathrm{mJ/cm^{2}} across millimeter-scale regions.