Gaze Stability During Ocular Proton Therapy: Quantitative Evaluation Based on Eye Surface Surveillance Videos.

Ocular proton therapy (OPT) is acknowledged as a therapeutic option for the treatment of ocular melanomas. OPT clinical workflow is deeply based on x-ray image guidance procedures, both for treatment planning and patient setup verification purposes. An optimized eye orientation relative to the proton beam axis is determined during treatment planning and it is reproduced during treatment by focusing the patient gaze on a fixation light conveniently positioned in space. Treatment geometry verification is routinely performed through stereoscopic radiographic images while real time patient gaze reproducibility is qualitatively monitored by visual control of eye surface images acquired by dedicated optical cameras. We described an approach to quantitatively evaluate the stability of patients’ gaze direction over an OPT treatment course at the National Centre of Oncological Hadrontherapy (Centro Nazionale di Adroterapia Oncologica, CNAO, Pavia, Italy).