1. A computer system for determining an objective tumor response to an anti-cancer therapy using cross-sectional images, the computer system comprising: one or more processors; and one or more computer readable hardware storage devices, wherein the one or more computer readable hardware storage devices comprise computer executable instructions executable by at least one of the one or more processors to cause the computer system to perform at least the following: receive a cross-sectional image, wherein the cross-sectional image comprises a cross-sectional slice of digital medical image data captured at a first point in time from a radiologic device; identify a set of pixels within the cross-sectional image, the set of pixels corresponding to a target lesion; analyze the set of pixels with an image processing module, wherein for the set of pixels, the image processing module performs the following: identify a total range of pixel intensities within the set of pixels; identify a lower threshold of pixel intensities within the total range of pixel intensities, wherein the lower threshold comprises about +20 Hounsfield units when injected radiocontrast is absent and about +40 Hounsfield units when injected radiocontrast is present; identify an upper threshold of pixel intensities within the total range of pixel intensities, wherein the upper threshold comprises at least about +200 Hounsfield units; define a subset of pixels from the set of pixels that correspond to vascularized tumor, wherein the subset of pixels comprises pixels having pixel intensities greater than or equal to the lower threshold and lower than or equal to the upper threshold; and determine one or more lesion metrics based on the set of pixels; derive a vascular tumor burden for the set of pixels, wherein deriving the vascular tumor burden comprises determining an area of pixels corresponding to the subset of pixels; determine the objective tumor response for the target lesion, wherein the objective tumor response is based on the vascular tumor burden; and display a summary image, wherein the summary image comprises an illustration comprising one or more of a numeric value, a graphical output, and a pictorial illustration of the vascular tumor burden.