Abstract: Apparatus for the generation of an image of a blood vessel comprises an x-ray source to irradiate the vessel. X-ray image collection means receive the x-ray image of the vessel and conversion means convert the x-ray image into a visible image of the vessel. A collimator selects an elongate field of illimunation representative of a section of the blood vessel. A light detecting array receives the field of illumination and has a plurality of discreet detectors spaced along the axis of the elongated field. Each detector has a length at least equal to the width f the elongate field produces a signal upon impingement by the elongate field. The array is scanned sequentially to output the signals in series. The signals are then displayed as one line of a video display.