1. A computer-implemented method comprising: receiving imaging data, wherein the imaging data indicates a tumor and one or more tissues that surround the tumor; determining one or more radial segments that extend from the tumor to the one or more surrounding tissues based on the imaging data, wherein the one or more radial segments each comprise one or more respective data points indicating signal intensity; determining one or more respective tumor boundary parameters for each of the one or more radial segments based on at least the one or more respective data points indicating signal intensity, wherein each of the one or more radial segments intersect a tumor boundary; based on the one or more determined tumor boundary parameters, determining a tumor margin that is outside of the tumor boundary and at least partially within a transition region between the tumor boundary and the one or more tissues that surround the tumor, wherein the determined tumor margin represents a surface along which the tumor is to be resected during surgery; and causing a graphical representation of the determined tumor margin to be displayed on a graphical display.