Data augmentation can effectively resolve a scarcity of images when training machine-learning algorithms. It can make them more robust to unseen images. We present a lesion conditional Generative Adversarial Network (LcGAN ) to generate synthetic Computed Tomography (CT) images for data augmentation. A lesion conditional image (segmented mask) is an input to both the generator and the discriminator of the LcGAN during training. The trained model generates contextual CT images based on input masks. We quantify the quality of the images by using a fully convolutional network (FCN) score and blurriness. We also train another classification network to select better synthetic images. These synthetic CT images are then augmented to our hemorrhagic lesion segmentation network. By applying this augmentation method on 2.5%, 10% and 25% of original data, segmentation improved by 12.8%, 6% and 1.6% respectively.
Introduction
Although deep learning architectures have solved challenging computer vision tasks in recent years [1], [2],[3], they require large amounts of data. In the medical field, collecting this vast amount of data is still quite challenging, and models tend to overfit if trained with limited data. As a solution to this problem, synthetic data is commonly added. Standard image transformation techniques like rotations, rescaling and contrast changes are some traditional methods of augmenting image datasets. These methods provide some variations in the dataset when there are a small number of samples. Nonetheless, these methods are still limited [4], as each new synthetic image is a transformation of a single image.