Interobserver Variability of Gross Tumor Volume Delineation for Colorectal Liver Metastases Using Computed Tomography and Magnetic Resonance Imaging oleh Cora Marshall, MSc, Pierre Thirion, MD, Alina Mihai, MD, John G. Armstrong, MD, Seán Cournane, PhD, Darina Hickey, MSc, Brendan McClean, PhD, John Quinn, PhD