Investigation Of A Video Frame Averaging Digital Subtraction Fluoroscopic System

A digital subtraction fluoroscopic (DSF) system with two video processors in series has been analyzed and evaluated clinically. In this system the initial processor operates simultaneously in an averaging and differencing mode, resulting in an output that is the difference between the most recent input video frame and an exponentially weighted average of preceeding frames. The content in this processor's memory (the mask image) is continually upgraded by each incoming frame or, alternatively, frozen in time by the operator. The second processor averages the difference image output from the first unit. A continuous, real-time, noise reduced subtraction sequence is viewed on a monitor and stored on an analog disc recorder. A video tape recorder preserves raw data and permits retrospective viewing of an injection sequence using different processor settings.