9 ELECTRICALLY OPERATED VIDEO DISC RECORDER, WHICH RECORDS AND PLAYS BACK SINGLE FIELDS OR FRAMES OF VIDEO INFORMATION ON ANY ONE OF A NUMBER OF AVAILABLE DISCRETE TRACKS, AND WHICH IS USED IN SUCH X-RAY AND INDUSTRIAL APPLICATIONS AS, INTER ALIA, PULSED FLUOROSCOPY, SPOT FILM RECORDING ELECTRONIC RADIOGRAPHY, X-RAY TOMOGRAPHY AND BAGGAGE X-RAY