APPARATUS AND METHOD FOR PRODUCING IMAGES CORRESPONDING TO PATTERNS OF HIGH ENERGY RADIATION

1433950 Producing radiographs EASTMAN KODAK CO 28 Dec 1973 [2 Jan 1973] 60063/73 Heading H4F A radiograph is produced by exposing a stimulable temporary image storage medium (such as an infra red stimulable phosphor or thermoluminescent material) to an X-ray image, scanning the medium with radiation (e.g. infra-red or heat) to stimulate the medium and cause emission of further radiation where the medium has been exposed to the X-ray image, and scanning a photosensitive element with radiation modulated as a functon of the further radiation emitted by the corresponding point of the stimulated image stcrage medium. The resulting radiograph may thus have a smaller format than the X-ray image and may for example be produced on microfilm. Preferably the further radiation comprises light in the visible, infra-red or ultra-violet ranges which is incident on an image intensifier whose modulated light output is scanned over photosensitive material in synchronism with the scanning of the image storage medium. The scanning may be effected by placing the exposed image storage medium and the photo-sensitive material on respective axially movable and rotatable drums, or on the flat beds of respective X-Y scanners. The Specification includes examples of phosphors which are transparent to their own emitted radiation and have the required image retentivity. The image intensifier may be replaced by a photo-multiplier tube, resulting video signal output being recorded on magnetic tape, displayed on a CRT the face plate of which is exposed to a microfilm or used to modulate a light source (e.g. visible or ultraviolet) which is scanned across the photosensitive recording material. Alternatively direct electron beam recording of the image on a film may be employed or the phosphor output may be recorded electrostatically with a discharge tube. Reference is also made to scanning the storage medium with infra-red or heat and collecting the emitted electrons to form a video signal which is displayed on a CRT and recorded.