US 4,792,900 AGranted

Adaptive filter for dual energy radiographic imaging

AssigneePicker International, Inc.

InventorsRichard A. Sones, Karen L. Lauro

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Abstract

A radiographic scanner (A) generates a high energy image representation which is stored in a high energy image matrix (V) and a low energy image representation which is stored in a low energy image memory (U). A pair of filter functions selecting circuits (C) select a first or soft tissue specific filter function and second or bone specific filter function, respectively. The soft tissue filter function selecting circuit selects and adjusts the soft tissue filter function in accordance with the pixel value of the low energy image representation for each corresponding pair of pixel values. Convolvers (44, 46) convolve pixel values from the high and low energy image representations with the selected and adjusted filter functions. A soft tissue transform function (48) transforms the filtered high and low energy image representations into a soft tissue or other material specific image representation (42). The other filter selecting and adjusting circuit selects and adjusts the bone specific filter functions which are convolved with the high and low energy image representations by convolvers (54, 56). A bone specific transform function (58) transforms the filtered high and low energy image representations into a bone basis image.

Claims21

Dependent claims

A medical diagnostic imaging apparatus for producing soft tissue and bone specific basis images from dual energy radiation data, the apparatus comprising:

a radiation source for producing at least higher energy and lower energy radiation;
a radiation detection means for separately detecting the higher and lower energy radiation traversing a selected region of interest and for producing digital electronic values indicative of the intensity of higher and lower energy radiation received thereby;
a higher energy image memory means operatively connected with the detection means for storing the higher energy radiation intensity indicative digital electronic pixel values for each pixel for a higher energy image representation of the region of interest;
a lower energy image memory means operatively connected with the detection means for storing the lower energy radiation intensity indicative digital electronic pixel values for each pixel for a lower energy image representation of the region of interest;
a first convolver means for convolving a first filter function pixel by pixel with the digital values of the higher energy image representation and for convolving the first filter function pixel by pixel with the digital values of the lower energy image representation;
a first filter function altering means for correspondingly adjusting a characteristic of the first filter function in accordance with the digital value of each pixel of at least one of the higher and lower energy image representations;
a first transform means for transforming convolved values of corresponding pixels of the higher and lower energy representations into a digital gray scale value of a corresponding pixel of a soft tissue specific basis image;
a soft tissue image memory means operatively connected with the first transform means for storing the gray scale values of the soft tissue basis image;
a second convolver means for convolving a second filter function with the digital values of the higher energy image representation and convolving the second filter function with the digital values of the low energy image representation;
a second filter function altering means for correspondingly adjusting a characteristic of the second filter function in accordance with the digital value of each pixel of at least one of the high and low energy image representations;
and,
a second transform means for transforming convolved values of corresponding pixels of the higher and lower energy image representations from the second convolver means into a digital gray scale value of a corresponding pixel of a bone specific basis image.

9 more elements

An apparatus for producing diagnostic images, the apparatus comprising:

a first image memory means for storing an electronic pixel value for each pixel of a first image representation;
a second image memory means for storing an electronic pixel value for each pixel of a second image representation;
a first filter means for operating on each pixel value of the first image representation from the first memory means with a first filter function and for operating on each pixel value of the second image representation from the second memory means with the first filter function;
a first transform means for transforming filtered pixel values from the first and second memory means into a first composite image;
and,
a first composite image memory means for storing the first composite specific image.

3 more elements

An apparatus for diagnostic imaging comprising:

a first image memory which stores a plurality of pixel values, each pixel value corresponding to a pixel of an image representation;
a comparing means for comparing each pixel value from the first image memory with a preselected criteria;
a filter function altering means for selecting characteristics of a filter function for each pixel to be filtered in accordance with the comparison of the pixel value with the preselected criteria, the pixel value altering means being operatively connected with the comparing means;
and,
a first filtering means for operating on the pixel values of each pixel and pixels thereadjacent with the selectively altered filter function, the first filtering means being operatively connected to the first image memory, whereby the filter function with which each pixel is filtered varies in accordance with its pixel value.

2 more elements

A method of diagnostic imaging comprising:

(a) generating first and second image representations of the same region of a subject;
(b) filtering the first image representation with a first filter function to produce a filtered first image representation;
(c) filtering the second image representation with the first filter function to produce a filtered second image representation;
and,
(d) transforming the filtered first and second image representations with a first transform function into a first composite image.

2 more elements

Dependencies are inferred from the claim text.