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Method and apparatus for automatic muscle segmentation in digital mammograms

  • US 6,035,056 A
  • Filed: 03/27/1997
  • Issued: 03/07/2000
  • Est. Priority Date: 03/27/1997
  • Status: Expired due to Fees
First Claim
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1. A method of identifying a pectoral boundary in a digital mammogram, said pectoral boundary being characterized by at least one parameter, comprising the steps of:

  • determining a region of interest containing said pectoral boundary;

    calculating gradient magnitudes inside said region of interest;

    accumulating said gradient magnitudes into a parameter plane, represented by H(ρ



    ), according to a Hough transform; and

    using information in said parameter plane for identifying said at least one parameter of said pectoral boundary;

    wherein said step of using information in said parameter plane comprises the steps of;

    selecting a parameter plane region of interest corresponding to the range of possible angles normal to said pectoral boundary;

    creating a normalized parameter plane HN(ρ



    ) by normalizing the value H(ρ



    ) by a normalizing factor, said normalizing factor being inversely related to the number of gradient magnitude pixels capable of being accumulated at (ρ



    );

    identifying a highest ranking local peak of said normalized parameter plane HN(ρ



    ); and

    using the location of said highest ranking local peak for determining said at least one parameter of said pectoral boundary; and

    wherein said normalizing factor is determined for each pixel (ρ



    ) by the steps of;

    backprojecting a line corresponding to (ρ



    ) into the image plane;

    determining the length L of said line; and

    setting said normalizing factor equal to 1/sqrt(L) if L is greater than a first number of pixels.

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