Fundus image fusion in EYEPLAN software: An evaluation of a novel technique for ocular melanoma radiation treatment planning

Abstract

Purpose:The purpose of this study is to evaluate a novel approach for treatment planning using digital fundus image fusion in EYEPLAN for proton beam radiation therapy ͑PBRT͒ planning for ocular melanoma. The authors used a prototype version of EYEPLAN software, which allows for digital registration of high-resolution fundus photographs. The authors examined the improvement in tumor localization by replanning with the addition of fundus photo superimposition in patients with macular area tumors. Methods:The new version of EYEPLAN ͑v3.05͒ software allows for the registration of fundus photographs as a background image. This is then used in conjunction with clinical examination, tantalum marker clips, surgeon's mapping, and ultrasound to draw the tumor contour accurately. In order to determine if the fundus image superimposition helps in tumor delineation and treatment planning, the authors identified 79 patients with choroidal melanoma in the macular location that were treated with PBRT. All patients were treated to a dose of 56 GyE in four fractions. The authors reviewed and replanned all 79 macular melanoma cases with superimposition of pretreatment and post-treatment fundus imaging in the new EYEPLAN software. For patients with no local failure, the authors analyzed whether fundus photograph fusion accurately depicted and confirmed tumor volumes as outlined in the original treatment plan. For patients with local failure, the authors determined whether the addition of the fundus photograph might have benefited in terms of more accurate tumor volume delineation. Results: The mean follow-up of patients was 33.6Ϯ 23 months. Tumor growth was seen in six eyes of the 79 macular lesions. All six patients were marginal failures or tumor miss in the region of dose fall-off, including one patient with both in-field recurrence as well as marginal. Among the six recurrences, three were managed by enucleation and one underwent retreatment with proton therapy. Three patients developed distant metastasis and all three patients have since died. The replanning of six patients with their original fundus photograph superimposed showed that in four cases, the treatment field adequately covered the tumor volume. In the other two patients, the overlaid fundus photographs indicated the area of marginal miss. The replanning with the fundus photograph showed improved tumor coverage in these two macular lesions. For the remaining patients without local failure, replanning with fundus photograph superimposition confirmed the tumor volume as drawn in the original treatment plan. Conclusions: Local control was excellent in patients receiving 56 GyE of PBRT for uveal melanomas in the macular region, which traditionally can be more difficult to control. Posterior lesions are better defined with the additional use of fundus image since they can be difficult to mark surgically. In one-third of treatment failing patients, the superposition of the fundus photograph would have clearly allowed improved localization of tumor. The current practice s...

Ultra‐widefield fundus photography for radiation therapy planning of ocular tumours

“…In the majority of cases, when the tumour was within 6 mm of the optic disc, distortions appeared clinically insignificant which is in line with a previous paper that reported the reliability of SF as compared to surgical mapping for posterior tumours (Daftari et al. ). For anteriorly located tumours and large tumours, we found that distortion increased in function of the distance from the optic disc.…”

“…() recently showed that UWF were distorted in the horizontal plane, but other authors found a nonuniformly distributed deformation of the images (Daftari et al. ; Muttuvelu & Kiilgaard ). More generally, distortions may be explained by the fact that fundus imaging is a projection of a curved surface on a plane surface, as seen on a world map.…”

“…; Daftari et al. ). Magnetic resonance imaging (MRI) is highly relevant to diagnose ocular melanomas and to assess extra‐scleral extension (Peyster et al.…”

“…), and it has previously been shown that while distortion is minimal near the posterior pole of the eye and increases as the peripheral retina is approached (Daftari et al. ; Oellers et al. ).…”

Imaging the intraocular tumor

“…Accurate axial length measurements are essential when planning proton beam radiotherapy, as these data are used to create a volumetric model of planned radiation treatment zones [26]. Accurate and precise measurements of tumor thickness are crucial, as they often directly impact assumptions made about a tumor's growth over time, calculations regarding radiotherapy, response to treatment and, especially in the case of uveal melanoma, its risk of metastatic spread [27,28].…”