Personalized treatment planning in eye brachytherapy for ocular melanoma: Dosimetric analysis on ophthalmic structure at risk

• DOI: 10.1016/j.ejmp.2020.07.019
• Publication Date: 2020-07-29T11:26:43Z
• Authors: F. Itta; R. Liuzzi; A. Farella; G. Porri; R. Pacelli; M. Conson; C. Oliviero; F. Buonanno; M.A. Breve; G. Cennamo; S. Clemente; L. Cella
• Keywords: Ocular Melanoma; Dose-volume histogram

To evaluate the impact on dose distribution to eye organs-at-risk (eOARs) of a computed tomography (CT)-based treatment planning in eye plaque brachytherapy (EPB) treatment.We analyzed 19 ocular melanoma patients treated with ruthenium-106 plaques to a total dose of 100 Gy to tumor apex using conventional central-axis-point dose calculation. Treatments were re-planned using the Plaque Simulator (PS) software implementing two different strategies: a personalized CT-eye-model (CT-PS) and a standard-eye-model (SEM-PS) defined by Collaborative Ocular Melanoma Study. Dice coefficient and Hausdorff distance evaluated the concordance between eye-bulb-models. Mean doses (Dmean) to tumor and eOARs were extracted from Dose-Volume-Histograms and Retinal-Dose-Area-Histogram. Differences between planning approaches were tested by Wilcoxon signed-rank test.In the analyzed cohort, 8 patients (42%) had posterior tumor location, 8 (42%) anterior, and 3 (16%) equatorial. The SEM did not accurately described the real CT eye-bulb geometry (median Hausdorff distance 0.8 mm, range: (0.4-1.3) mm). Significant differences in fovea and macula Dmean values were found (p = 0.04) between CT-PS and SEM-PS schemes. No significant dosimetric differences were found for tumor and other eOARs. The planning scheme particularly affects the OARs closest to the tumor with a general tendency of SEM-PS to overestimate the doses to the OARs closest to the tumor.The dosimetric accuracy achievable with CT-PS EPB treatment planning may help to identify ocular melanoma patients who could benefit the most from a personalized eye dosimetry for an optimal outcome in terms of tumor coverage and eOARs sparing. Further research and larger studies are underway.