If possible, have the Ophthalmologist provide the completed collage as a .jpg file or as a print that you can digitize on a flatbed scanner. Many fundus cameras provide collages now. If you receive a set of fundus pictures, the recommended method for creating a collage for Plaque Simulator is to use the Adobe Photoshop program to assemble the collage manually and export it as a .jpg file.
The fundus collage is used to digitize the location, appearance, and perimeter of the tumor base on the retinal surface with respect to retinal landmarks that can also be identified in CT imaging space.
Two landmarks that are readily identifiable in fundus photography are the optic disc and macula. The location of the optic disc can be closely estimated in 3D CT (or MR) imaging space by reconstructing a meridian plane which bisects the eye and passes through the center of the optic nerve. This meridian plane, by definition, will also pass through the posterior pole of the eye. The posterior pole can be closely estimated in the fundus photos because the macula is adjacent to the pole.
Therefore, in order to accomplish the fundus-CT fusion, the fundus collage MUST contiguously include as much of the tumor as can be photographed as well as the macula and optic disc.
When properly calibrated, the end of the fundus ruler centered on the optic disc should now have a 1 mm radius magenta circle surrounding it, just outside the border of the optic disc.