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Digital subtraction fluorographic method and apparatus

  • US 4,633,307 A
  • Filed: 09/05/1985
  • Issued: 12/30/1986
  • Est. Priority Date: 09/13/1984
  • Status: Expired due to Fees
First Claim
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1. A method for producing video signals representing phase difference images from X-ray images of a subject, which phase difference images are produced during a time period in which a contrast medium is flowing in the vessel of the subject, after intravenous injection of the contrast medium in the subject, comprising:

  • acquiring a sequence of X-ray images in the form of video signals starting at the beginning of a pre-contrast period and continuing through a post-contrast period;

    producing difference video signals by performing a subtraction between the video signals of the pre-contrast images and the video signals of the post-contrast images;

    converting the difference video signals to pixel image data representative of the intensity of contrast medium at the respective pixels in the difference video signals;

    comparing the value of the pixel image data of the difference image with a predetermined threshold intensity value;

    determining, for each pixel, time data related to the time period until the intensity of the respective pixel image data reaches the predetermined threshold intensity value after acquiring a sequence of X-ray images; and

    converting said time data for each pixel into visible televison images representing the distribution of contrast medium in the vessel in relation to the time period it takes for each pixel to attain said predetermined threshold intensity value.

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