30 years of ocular proton therapy, the Nice view

Radiotherapy with protons (PT) is a standard treatment of ocular tumors. It achieves excellent tumor control, limited toxicities, and the preservation of important functional outcomes, such as vision. Although PT may appear as one homogenous technique, it can be performed using dedicated ocular passive scattering PT or, increasingly, Pencil Beam Scanning (PBS), both with various degrees of patient-oriented customization. MEDICYC PT facility of Nice are detailed with respect to their technical, dosimetric, microdosimetric and radiobiological, patient and tumor-customization process of PT planning and delivery that are key. 6684 patients have been treated for ocular tumors (1991–2020). Machine characteristics (accelerator, beam line, beam monitoring) allow efficient proton extraction, high dose rate, sharp lateral and distal penumbrae, and limited stray radiation in comparison to beam energy reduction and subsequent straggling with high-energy PBS PT. Patient preparation before PT includes customized setup and image-guidance, CT-based planning, and ocular PT software modelling of the patient eye with integration of beam modifiers. Clinical reports have shown excellent tumor control rates (∼95%), vision preservation and limited toxicity rates (papillopathy, retinopathy, neovascular glaucoma, dry eye, madarosis, cataract). Although demanding, dedicated ocular PT has proven its efficiency in achieving excellent tumor control, OAR sparing and patient radioprotection. It is therefore worth adaptations of the equipments and practice. Some of these adaptations can be transferred to other PT centers and should be acknowledeged when using non-PT options. La protonthérapie est un traitement de précision pour les tumeurs oculaires. Elle permet d’obtenir un excellent taux de contrôle tumoral, et parfois de préserver la vision. La protonthérapie peut être réalisée en diffusion passive ou en Pencil Beam Scanning (PBS), avec différents niveaux de personnalisation possibles et differentes performances en fonction des caracteristiques liées au patient, à la tumeur et à la fonction visuelle avant traitement. Les caractéristiques du faisceau et équipements du cyclotron médical MEDICYC de Nice sont décrits en termes de production d’ions, d’accessoires modificateurs du faisceau, de processus dosimétriques, de caractéristiques microdosimétriques et radiobiologiques. Les caractéristiques du cyclotron MEDICYC permettent une extraction efficace, un débit de dose élevé, une énergie a