Described herein are methods and systems for determining tumor boundary characteristics. One example method involves (a) receiving imaging data, wherein the imaging data indicates a tumor and one or more tissues that surround the tumor (b) 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 (c) 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 (d) determining a tumor margin based on the one or more determined tumor boundary parameters and (e) causing a graphical representation of the determined tumor margin to be displayed on a graphical display.
