A robot-assisted eye positioning method with high precision and repeatability for ocular particle therapy: mechanical and geometric assessment.

Noninvasive ocular particle therapy requires precise eye positioning. While static guidance systems lack gaze flexibility, existing dynamic robot-assisted systems are limited by severe workflow disruptions in shared clinical environments and a lack of kinematic occlusion models to guarantee safety. To overcome these limitations, an eye positioning and monitoring system (EPMS) was developed. A gaze range analysis algorithm and an occlusion zone analytical algorithm for the beam path and cameras were proposed. Furthermore, a mechanical reproducibility assessment quantified the system's performance under busy preoperative disruptions, including powering off/reconnecting and uninstalling/reinstalling. The EPMS mechanical guidance range reached 360° azimuth and 60.1° maximum polar, while identifying specific exclusion zones. Stability tests demonstrated cumulative workflow errors were always ≤ 0.22 mm and 0.01° for the guidance module, and ≤ 0.20 mm and 0.1° for the monitoring module. Corresponding eyeball rotation deviations were 0.25° (SD 0.13°) in polar and 0.09° (SD 0.07°) in azimuth. The EPMS demonstrates robust reproducibility, validating its adaptability to conventional radiotherapy environments without requiring dedicated ophthalmology treatment rooms.