Medical Image Processing Apparatus for Artifact Reduction
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Solution Overview
Problem
Conventional dual-energy CT methods struggle to generate monochromatic X-ray images that eliminate artifacts caused by highly-absorbent materials and scattered rays, as they cannot properly obtain projection data due to the degradation in precision levels, leading to missing information around these materials.
Innovation Solution
A medical image processing apparatus that separates projection data into line-integrated data for basis materials, reconstructs basis material images, extracts artifact regions based on attenuation coefficients, and corrects these coefficients using a specific energy level to generate accurate monochromatic X-ray images.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If dual-energy CT method is used to correct beam hardening artifacts, then beam hardening artifacts are reduced, but other artifacts caused by highly-absorbent materials and scattered rays cannot be eliminated
Solution Approach 1:
The projection data is segmented into multiple components corresponding to different basis materials (e.g., soft tissue, bone, contrast agent) through decomposition. This segmentation allows separate handling and correction of artifacts affecting different material types, enabling more comprehensive artifact removal beyond what conventional dual-energy CT achieves.
Solution Approach 2:
The method changes the parameter of X-ray energy by acquiring projection data at multiple different energy levels. This multi-energy approach enables the system to capture material-specific attenuation characteristics and scattered ray effects at different energies, providing additional information for artifact correction that single-energy or conventional dual-energy methods cannot obtain.
2Illumination intensity
If low level X-ray tube voltage is used during image taking, then image contrast is improved, but projection data precision degrades due to highly-absorbent materials
Solution Approach 1:
The method applies partial action by using multiple X-ray voltage levels rather than a single low voltage. While low voltage provides good contrast, the multi-voltage approach selectively combines data from different voltage levels, using low voltage for contrast-enhanced regions and higher voltage for regions with highly-absorbent materials, thus maintaining both contrast and precision.
Solution Approach 2:
The projection data is treated as a composite of multiple basis materials, each with different attenuation properties. By decomposing the total attenuation into contributions from individual basis materials, the system can correct for the non-linear attenuation effects of highly-absorbent materials and recover accurate projection data even when using low X-ray voltages for contrast enhancement.
3Device complexity
If conventional dual-energy CT method is used, then processing complexity is reduced, but artifact removal completeness is insufficient
Solution Approach 1:
The projection data is segmented into multiple components corresponding to different basis materials (e.g., soft tissue, bone, contrast agent) through decomposition. This segmentation allows separate handling and correction of artifacts affecting different material types, enabling more comprehensive artifact removal beyond what conventional dual-energy CT achieves.
Solution Approach 2:
The method adds an energy dimension by acquiring data at multiple X-ray voltage levels, transforming the problem from two-dimensional (single energy level with two projections) to three-dimensional (multiple energy levels). This additional dimensional information enables more robust artifact correction while the basis material decomposition framework organizes the complexity systematically.
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
The solution effectively reduces artifacts in monochromatic X-ray images by correcting attenuation coefficients, improving image quality and reducing the impact of highly-absorbent materials and scattered rays, allowing for more accurate imaging.
Implementation Method 1
image taking processing is performed by an X-ray Computed Tomography (CT) apparatus while using multi different levels of X-ray tube voltages
Implementation Method 2
two projection data obtained from two mutually-different levels of X-ray tube voltages are separated into projection data (line-integrated data) each corresponding to respective predetermined two basis materials
Data Source
AI summary
A medical image processing apparatus according to an embodiment includes a separating unit, a reconstructing unit, and an extracting unit. The separating unit separates projection data into pieces of line-integrated data each of which corresponds to a different one of basis materials set in advance. The reconstructing unit reconstructs pieces of basis material image data from the pieces of line-integrated data each of which corresponds to a different one of the basis materials, the pieces of basis material image data being configured so that each pixel value of each of pixels indicates an abundance ratio of corresponding each of the basis materials that is present at each of the pixel. The extracting unit extracts an artifact region, on a basis of attenuation coefficients of each of the pixels calculated from the pieces of basis material image data each of which corresponds to a different one of the basis materials.