Abstract
Purpose:
In patients with uveal melanoma treated with proton beam therapy (PBT) we compared the clinical target volume (CTV) and the distance tumor to macula and to optic disc based on OCTOPUS planning system using standard composite fundus image with the images captured with the ultra widefield OPTOS camera.
Methods:
In total 92 patients treated in our Department between January 2013 to October 2014 the standard 30° single images using Zeiss FF450IR camera with following fundus composite reconstruction and 200° ultrawidefield OPTOS 200TX device were perfomed. On the fundus pictures from both devices the tumor was delineated and the positions of the tantalum clips were marked. A high resolution computer tomography scan was acquired and used for the reconstruction of an eye model using the OCTOPUS planning system. A scan of the fundus was matched to the eye model by moving, rotating, adjusting in size, and deformating of the picture so, that papilla, fovea and clip positions overlapped. The outline from the fundus picture was transferred to the model as clinical target volume (CTV). Size and position of the CTV was cross checked with ultrasound, OCT, and measurements acquired during clip surgery. Based on this model a treatment plan was created. We compared the CTVs based on fundus composite (group 1) with CTVs based on the OPTOS images (group2). The CTVs; size, and the position of the tumor in respect to papilla, fovea and clips were analysed.
Results:
No significant differences (p=0,86) were observed in CTVs between group 1 (336,33 ± 228,57mm³) and group 2 (351,75 ± 244,24mm³). The mean distance tumor to optic disc and to macula was 2,25 ± 2,61mm and 3,77 ± 3,29mm in group 1 compared to 1,78±1,82mm and 3,32 ± 2,76mm in the group 2 respectively (p=0,75 and p=0,82). The highest observed individual difference in one patient based on these two analyzed images was 49 mm³ for the tumor volume (17,5 %), 1,8 mm for the distance to the papilla and 2,5mm for the distance to the macula.
Conclusions:
The treatment planning for the PBT based on composite fundus image and OPTOS image did not show significant differences in volume and the distance to the papilla and macula. Regarding to the shorter examination time of OPTOS ultra wide field device this technique seems to be favorable for the daily routine.