Direct Radiography Corp.

Sterling Diagnostic Imaging, Inc.

Cornell L Williams

Denny L Lee

Brian Rodricks

Michael Hoffberg

Eugene Francis Palecki

Ronald P Schwenker

A method for developing a set of gain correction coefficients corrected for structural noise to be used in correcting the digital values representing an image captured by a pixelated detector having a plurality of individual sensors. The gain correction coefficients are developed by first obtaining a first set gain correction coefficients using a flat exposure and adjusting the individual sensor gain output so that all sensors produce the same output value, and then applying a smoothing filter to the first set of gain correction coefficients to obtain a new set of corrected gain correction coefficients.

Method for calculating gain correction factors in a digital imaging system

A method for automatically identifying the range of useful digital values to be displayed on a display medium and providing an appropriate gray scale transfer to optimize the diagnostic value of the final displayed image. One or more gray scale transfer functions corresponding to desired display media, one or more sets of experimentally determined constants, and one or more sets of algorithms are stored in a computer memory. A smoothed histogram and its histogram integral are constructed representing the frequency of occurrence of the digital values stored in the data bank. A low point and an edge point are identified from the histogram and integral, and based on the type of radiographic examination selected, are used with appropriate constants and algorithms to calculate a maximum and minimum value. Values lower than the minimum are replaced with the minimum, and values higher than the maximum are replaced by the maximum. The new range of values are mapped using the appropriate gray scale transfer function to a set of values displayed on the display medium.

Image data processing for digital x-ray detectors

A method for automatically forming a filtered subset of digital values from a first set of digital values corresponding to a plurality of picture elements representing a radiographic exposure of a subject for use in displaying a radiograph of said subject, the method comprising: (1) generating a first histogram of the first set of digital values; (2) generating an integral curve representing an integral of the first histogram; (3) identifying an inflection point and corresponding digital value V.sub.peak1 on the first histogram integral where the integral curve first changes slope in a direction decreasing from the highest digital value; (4) calculating a parameter V.sub.test =V.sub.peak1 -AR wherein AR represents an anatomical range of the subject; (5) spatially dividing the first set of digital values into multiple block subsets of digital values, each block subset comprising digital values from a neighborhood of pixels consisting of a predetermined number of picture elements; (6) constructing a subset histogram representing the frequency of occurrence of digital values within each block subset; (7) determining a low point of each block subset, BV.sub.low, corresponding to a predetermined low point of the subset histogram; (8) comparing each BV.sub.low to V.sub.test ; and (9) forming the filtered subset of digital values from the digital values of all the block subsets having BV.sub.low greater than V.sub.test.

Method for automatic detection of region of interest for digital x-ray

A process and related apparatus for reducing noise due to addressing and switching the detection elements in a radiation detecting panel comprising an array of detection elements. Noise reduction is achieved in two steps, first by the use of a sample and hold circuit which compares a first signal indicative of switching noise held in a sample and hold circuit with a second signal which includes the switching noise and the desired data signal. The second step includes further reducing noise in the output signal present during readout of the detection elements by comparing the signal from certain elements in the array which have not been exposed to radiation with the signal from the exposed elements in the array to obtain an output with significantly reduced noise.

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Pennsauken, NJ, United States of America

Cornell L Williams