MTF Measurement via LSF Center Detection in X-ray CT
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Solution Overview
Problem
Precise measurement of the modulation transfer function (MTF) in X-ray computed tomography systems is hindered by errors in detecting the center of the line spread function (LSF) due to noise influence.
Innovation Solution
A method and system that create an enlarged binary-coded image of the LSF, perform morphological operations, and use Hough transforms to accurately determine the center coordinates, allowing for a two-dimensional Fourier transform to calculate the MTF.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the center of LSF is detected by finding the point with the largest pixel value, then the detection process is simple, but the measurement precision of MTF deteriorates due to noise influence
Solution Approach 1:
The patent creates an enlarged image of the LSF region before performing center detection. This preliminary enlargement allows for more precise identification of the center point by providing a magnified view of the critical area, thereby improving measurement precision while maintaining operational simplicity through automated processing.
Solution Approach 2:
The patent transforms the one-dimensional pixel value comparison into a two-dimensional coordinate system analysis. By working with coordinate pairs (x, y) and performing morphological operations on binary-coded images, the system achieves more accurate center localization that is less susceptible to noise, thus improving MTF measurement precision.
2Device complexity
If the center of LSF is detected by finding the point with the largest pixel value, then the computational complexity is low, but the detection precision deteriorates due to noise
Solution Approach 1:
The patent performs preliminary binary coding and morphological operations on an enlarged image before final center detection. These preliminary steps filter out noise and enhance the LSF features, making the subsequent center detection more precise while keeping the overall computational complexity manageable through systematic processing stages.
Solution Approach 2:
The patent replaces the simple mechanical approach of finding the maximum pixel value with a more sophisticated image processing system involving binary coding, morphological operations, and coordinate transformation. This substitution increases detection precision by using multiple processing steps that are less sensitive to noise, while the automated nature of these operations keeps computational complexity acceptable.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables highly precise detection of the LSF center and subsequent calculation of the MTF, enhancing the accuracy of X-ray CT system performance assessment.
Implementation Method 1
coordinates representing points sampled along the contour of the resultant image are worked out, and used to calculate coordinates representing the center of a circle through Hough transform
Implementation Method 2
A morphological operation is performed on the binary-coded image
Implementation Method 3
a two-dimensional Fourier transform of the LSF image with the center as a reference so as to thus calculate an MTF
Data Source
AI summary
A method of measuring a modulation transfer function (MTF) includes detecting the center of a line spread function (LSF) image in order to calculate an MTF. For this purpose, an enlarged image of a portion of an image containing the LSF image is created, and binary-coded based on a threshold. A morphological operation is performed on the binary-coded image. Coordinates representing points that define the contour of the resultant image are sampled, and used to work out coordinates representing the center of a circle through Hough transform. The coordinates representing the center are transformed into coordinates representing a point in an original image.