Automated Treatment Planning System for Uveal Melanomas Treated With Proton Therapy: A Proof-of-Concept Analysis

Purpose: By precalculation of an entire set of planning solutions for protons, penalizing them and providing a graphical navigator tool (Automated Treatment Planning [ATP]), we aim to improve the efficiency of the planning procedure for uveal melanoma (UM) and make it independent of treatment planner experience. Methods and Materials: A phase space of plans is evaluated by transforming the eye model in each gaze angle, calculating cumulative dose-volume histograms for each position, and defining a dose-volume constraint for each considered structure. The final result is a map of the plan phase space, displaying how many criteria are fulfilled for each gaze angle. Results: To test its usability and performance, ATP was used retrospectively on 48 UM patients treated with protons. In 36 of 48 cases (75%), the planning result was either the same (13 of 48, 27%) or comparable (23 of 48, 48%). In 11 of 48 evaluated cases (23%), ATP plans showed improvements. In 1 case (2%) the patient's visual acuity had been impaired, and an optimization was not possible. Conclusions: We have developed a dose calculation and planning engine that prepares a set of treatment plans covering a wide range of theoretical clinically feasible gaze angles for a given patient, by precalculating the dose distributions for each gaze angle. By considering different structures and adapting their constraints, the identification of the optimal gaze angle can be realized. With a better understanding of the dose-volume constraints and the development of strategies to react to the trade-offs between considered structures, ATP may lead to a complete automation of the planning process for UM treated with proton therapy. (C) 2018 Elsevier Inc. All rights reserved.