1. A method of collecting diagnostic data, the method comprising: capturing a series of frames at each of a plurality of successive times, the frames comprising radiographic imaging data of a bodily lumen of a patient as a radiographic contrast material transits through the lumen; processing the series of frames to compute: a plurality of fields, each field being representative of a region along the lumen, and for each frame, a quantitative indication of an amount of the contrast material; and providing as an output a quantitative indication of the amount of the contrast material at each of a plurality of locations along the bodily lumen as a function of time based on the computed quantitative indications.