Digital Subtraction Fluoroscopic System With Tandem Video Processing Units

Robert G. Gould; Martin J. Lipton; Paul Mengers; Roger Dahlberg

doi:10.1117/12.931794

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16 July 1981 Digital Subtraction Fluoroscopic System With Tandem Video Processing Units

Robert G. Gould, Martin J. Lipton, Paul Mengers, Roger Dahlberg

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Proceedings Volume 0273, Application of Optical Instrumentation in Medicine IX; (1981) https://doi.org/10.1117/12.931794
Event: Application of Optical Instrumentation in Medicine, 1981, San Francisco, United States

Abstract

A real-time digital fluoroscopic system utilizing two video processing units (Quantex) in tandem to produce continuous subtraction images of peripheral and internal vessels following intravenous contrast media injection has been inves-tigated. The first processor subtracts a mask image consisting of an exponentially weighted moving average of N1 frames (N1 = 2^k where k = 0.7) from each incoming video frame, divides by N1, and outputs the resulting difference image to the second processor. The second unit continuously averages N2 incoming frames (N2 = 2^k) and outputs to a video monitor and analog disc recorder. The contrast of the subtracted images can be manipulated by changing gain or by a non-linear output transform. After initial equipment adjustments, a subtraction sequence can be produced without operator interaction with the processors. Alternatively, the operator can freeze the mask and/or the subtracted output image at any time during the sequence. Raw data is preserved on a wide band video tape recorder permitting retrospective viewing of an injection sequence with different processor settings. The advantage of the tandem arrangement is that it has great flexibility in varying the duration and the time of both the mask and injection images thereby minimizing problems of registration between them. In addition, image noise is reduced by compiling video frames rather than by using a large radiation dose for a single frame, which requires a wide dynamic range video camera riot commonly available in diagnostic x-ray equipment. High quality subtraction images of arteries have been obtained in 15 anesthetized dogs using relatively low exposure rates (10-12 μR/video frame) modest volumes of contrast medium (0.5-1 ml/kg), and low injection flow rates (6-10 ml/sec). The results/ achieved so far suggest that this system has direct clinical applications.

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Robert G. Gould, Martin J. Lipton, Paul Mengers, and Roger Dahlberg "Digital Subtraction Fluoroscopic System With Tandem Video Processing Units", Proc. SPIE 0273, Application of Optical Instrumentation in Medicine IX, (16 July 1981); https://doi.org/10.1117/12.931794

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