A system and method for identifying an object based on its estimated mass. In one aspect, a method for estimating a mass of an object is provided. The method includes acquiring image data including a plurality of image elements, calculating a histogram based on the image data, calculating a computed tomography (CT) number of the object using an anisotropic erosion operator, and determining a perimeter of the object. The method also includes calculating an estimated mass of the object using the CT number and a first subset of image elements of the plurality of image elements, the first subset of image elements defined by the perimeter of the object, and outputting at least one of the estimated mass of the object and an image including the object.