An apparatus for recording the movements of the heart and great vessels or of the diaphragm on a single film. It consists of a lead sheet called the grid in which are cut horizontal or vertical slits, typically less than 1 mm wide, spaced 1-2 cm apart. During an X-ray exposure lasting as long as several cardiac or respiratory cycles, the grid or the film is moved vertically to record cardiac motion or horizontally for diaphragm motion.
(05 Mar 2000)
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