Quantifying the Real-Time Tracking Accuracy and Latency of an Sgrt System with Live Human Participants In a Simulated Clinical Environment
Abstract
Purpose
While phantom studies demonstrate high spatial accuracy for Surface-Guided Radiation Therapy (SGRT) systems, validation with live human subjects is critical. Non-rigid facial motion and the lack of a concurrent motion reference standard present unique challenges. This study quantifies the real-time tracking accuracy, latency, and operational robustness of a novel SGRT system (LUNA 3D) using a synchronized infrared (IR) marker system as a reference, in both phantom and live human participant scenarios.
Methods
The LUNA 3D system's performance was evaluated under varied surface colors, ambient lighting, and region-of-interest (ROI) sizes using a static head phantom. For human validation, a custom dental plate with four IR markers (Polaris, NDI) was fabricated for each healthy volunteer, providing a rigid skull motion reference. Volunteers were monitored supine for 15-minute sessions. The system clocks of the LUNA 3D and the IR camera were synchronized prior to data acquisition, ensuring precise temporal alignment of the two data streams.
Results
For the static phantom, LUNA 3D demonstrated sub-millimeter/sub-degree translational and rotational noise (RMSE: ~0.04-0.06 mm, ~0.04°). Under all tested color, lighting, and ROI conditions, its agreement with the IR camera was within 0.14 mm. The frame rate remained stable at ~12.5 fps regardless of ROI size. Preliminary data from human volunteers show comparable tracking performance to the phantom studies, with detailed analysis ongoing.
Conclusion
The LUNA 3D SGRT system demonstrated high static and dynamic tracking accuracy, robustness to clinical variables, and stable performance in a simulated clinical environment. The novel synchronization method enabled direct comparison with an IR reference in human subjects. Results indicate the system's potential for reliable, real-time surface tracking in frameless stereotactic applications.