Systems and methods of tumor segmentation are receiving data having dimensions of a first size and a first kernel size. A residual volume is produced from the input volume. A first, second, and third intermediate volume are produced by from convolving a first, second, and third dimension volume of the residual volume to 1. A first global volume is produced from sums of the residual volumes. A downsampled volume is produced from the input volume. A residual downsampled volume is produced from the downsampled volume. A first, second, and third intermediate downsampled volume is produced from convolving a first, second, and third dimension volume of the downsampled volume to 1. A second global volume is produced from sums of the intermediate downsampled volumes. The second global volume is upsampled. An output volume is produced from integrating the first global volume and the second global volume.