Scatter correction methods
First Claim
1. A correction method for reducing error in cone beam computed tomography images, the method comprising:
- generating a plurality of two-dimensional projection images of a subject from a three-dimensional multi-detector computed tomography image of the subject, which is spatially registered with a three-dimensional cone beam computed tomography image of the subject;
subtracting the plurality of two-dimensional projection images from a plurality of two-dimensional cone beam projection images of the subject, resulting in a plurality of two-dimensional estimated error projections, which comprise an estimated error in the plurality of two-dimensional cone beam projection images;
subtracting the plurality of two-dimensional estimated error projection images from the plurality of two-dimensional cone beam projection images to generate a plurality of two-dimensional corrected cone beam projection images;
constructing a three-dimensional corrected cone beam computed tomography image of the subject from the plurality of two-dimensional corrected cone beam projection images;
converting the three-dimensional multi-detector computed tomography image of the subject from Hounsfield Units to linear attenuation coefficients; and
spatially registering the converted three-dimensional multi-detector computed tomography image of the subject before generating the plurality of two-dimensional multi-detector projection images of the subject, wherein the spatially registering comprises;
placing a data set from the converted three-dimensional multi-detector computed tomography image of the subject in a same coordinate system as a data set from the three-dimensional cone beam computed tomography image of the subject; and
aligning a center of mass of the converted three-dimensional multi-detector computed tomography image of the subject with a center of mass of the three-dimensional cone beam computed tomography image of the subject.
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Accused Products
Abstract
Described herein are improved methods for correcting cone beam computed tomography signals to reduce scatter contamination contained therein. Generally, the improved methods involve generating a plurality of two-dimensional projection images of a subject from a three-dimensional multi-detector computed tomography image of the subject. This is followed by subtracting the plurality of two-dimensional projection images from a plurality of two-dimensional cone beam projection images of the subject to produce a plurality of two-dimensional estimated error projections that comprise an estimated error in the plurality of two-dimensional cone beam projection images. The plurality of two-dimensional estimated error projection images are subtracted from the plurality of two-dimensional cone beam projection images to generate a plurality of two-dimensional corrected cone beam projection images. A three-dimensional corrected cone beam computed tomography image of the subject is then constructed from the plurality of two-dimensional corrected cone beam projection images.
34 Citations
17 Claims
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1. A correction method for reducing error in cone beam computed tomography images, the method comprising:
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generating a plurality of two-dimensional projection images of a subject from a three-dimensional multi-detector computed tomography image of the subject, which is spatially registered with a three-dimensional cone beam computed tomography image of the subject; subtracting the plurality of two-dimensional projection images from a plurality of two-dimensional cone beam projection images of the subject, resulting in a plurality of two-dimensional estimated error projections, which comprise an estimated error in the plurality of two-dimensional cone beam projection images; subtracting the plurality of two-dimensional estimated error projection images from the plurality of two-dimensional cone beam projection images to generate a plurality of two-dimensional corrected cone beam projection images; constructing a three-dimensional corrected cone beam computed tomography image of the subject from the plurality of two-dimensional corrected cone beam projection images; converting the three-dimensional multi-detector computed tomography image of the subject from Hounsfield Units to linear attenuation coefficients; and spatially registering the converted three-dimensional multi-detector computed tomography image of the subject before generating the plurality of two-dimensional multi-detector projection images of the subject, wherein the spatially registering comprises; placing a data set from the converted three-dimensional multi-detector computed tomography image of the subject in a same coordinate system as a data set from the three-dimensional cone beam computed tomography image of the subject; and aligning a center of mass of the converted three-dimensional multi-detector computed tomography image of the subject with a center of mass of the three-dimensional cone beam computed tomography image of the subject. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A correction method for reducing error in cone beam computed tomography images, the method comprising:
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generating a plurality of two-dimensional projection images of a subject from a cone beam computed tomography scan of the subject; constructing a three-dimensional cone beam computed tomography image of the subject from the plurality of two-dimensional cone beam projection images; spatially registering a three-dimensional multi-detector computed tomography image of the subject with the three-dimensional cone beam computed tomography image of the subject; generating a plurality of two-dimensional projection images of the subject from the three-dimensional multi-detector computed tomography image of the subject; subtracting the plurality of two-dimensional multi-detector projection images from the plurality of two-dimensional cone beam projection images to generate a plurality of two-dimensional estimated error projections, wherein the plurality of two-dimensional estimated error projections comprise an estimated error in the plurality of two-dimensional cone beam projection images; low-pass filtering the plurality of two-dimensional estimated error projections; subtracting the plurality of low-pass filtered two-dimensional estimated error projection images from the plurality of two-dimensional cone beam projection images to generate a plurality of two-dimensional corrected cone beam projection images; and constructing a three-dimensional corrected cone beam computed tomography image of the subject from the plurality of two-dimensional corrected cone beam projection images, wherein spatially registering the three-dimensional multi-detector computed tomography image of the subject with the three-dimensional cone beam computed tomography image of the subject comprises; placing a data set from the three-dimensional multi-detector computed tomography image of the subject in a same coordinate system as a data set from the three-dimensional cone beam computed tomography image of the subject; aligning a center of mass of the three-dimensional multi-detector computed tomography image of the subject with a center of mass of the three-dimensional cone beam computed tomography image of the subject; calculating a square pixel-wise difference between a volume of the three-dimensional multi-detector computed tomography image of the subject with a volume of the three-dimensional cone beam computed tomography image of the subject; applying a gradient descent search algorithm to the square pixel-wise difference to determine an amount of rotation and offset for the three-dimensional multi-detector computed tomography image of the subject; rotating and offsetting the three-dimensional multi-detector computed tomography image of the subject by the amount determined; and repeating the calculating, applying, and rotating and offsetting until the amount determined is below a threshold amount. - View Dependent Claims (13, 14, 15, 16, 17)
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Specification