Abstract: The disclosure is directed to a method and apparatus for generating a processed video image of a fluid-carrying vessel in a body, and can also be used to obtain information concerning the flow rate of blood in the vessel. In the disclosed method, a contrast medium is injected into the body, typically into the vessel to be imaged or leading into the vessel to be imaged. A source of X-radiation is directed at the body, and radiation which passes through the body is detected and converted into a series of frames of electronic video signals, preferably in digital form. The frames represent images of the radiation transmission characteristics of the body at a series of successive times. Each frame includes an array of pixels, the video level at each pixel of a frame being determined by the radiation transmissivity of the body through an elemental region thereof.