Technical Note: Benchmarking automated eye tracking and human detection for motion monitoring in ocular proton therapy.

PURPOSE Ocular proton therapy (OPT) is an effective therapeutic option for patients affected with uveal melanomas (UMs). An optical eye tracking system (ETS) aiming at non-invasive motion monitoring was developed and tested in a clinical scenario. MATERIALS AND METHODS The ETS estimates eye position and orientation at 25 frames per second using the three-dimensional position of pupil and cornea curvature centres identified, in the treatment room, through stereoscopic optical imaging and infrared eye illumination. Its capabilities for automatic detection of eye motion were retrospectively evaluated on 60 treatment fractions. Then, the ETS performance was benchmarked against the clinical standard based on visual control and manual beam interruption. RESULTS ETS detected eye position successfully in 97% of all available frames. ETS-based eye monitoring during therapy guarantees quicker response to involuntary eye motions than manual beam interruptions and avoids unnecessary beam interruptions. CONCLUSIONS ETS shows promise for on-line monitoring of eye motion. Its introduction in the clinical workflow will guarantee a swifter treatment course for the patient and the clinical personnel.