Fig. 2

Image preprocessing on CT images for the deep learning analysis. First, a square region of interest (ROI) was manually placed to fully include the orbital wall on coronal CT images (red arrow). Next, segmented images by the ROI were extracted as continuous slices including the tumor. Then, right-side lesion images were inverted to the left side (flipped horizontally) and all images were aligned, as the lesion is shown at the left side. Thereafter, the top and outer areas in the image were masked (white asterisk). Finally, these processed images were fed into the data augmentation process with image rotation and/or a shift for training data