Importance

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Abstract

An improved method and apparatus for generating video images of the internal structure of a body is disclosed. A contrast medium is injected into the vessel to be imaged. 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. An initial video frame, i.e., the first video frame generated after the initiation of video processing, is stored in a digital video frame store. The video signal level at each pixel of the next frame is compared to the video signal level of the corresponding pixel of the stored frame. The lower of the two video signal levels being compared is selected and said selected video signal level is re-stored (in place of the previously stored value) at the particular pixel in the video frame store. This is done for each pixel of the frame. The process is then repeated for subsequent frames. In this manner, the stored video frame is dynamically processed to retain, at each pixel, a video signal level that represents the highest opacity to radiation during the video processing period through the elemental region of the body that corresponds geometrically to the particular pixel.

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First Claim