Energy-Resolved CT Motion Compensation via K-Edge Imaging
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Solution Overview
Problem
Current motion compensation techniques in computed tomography, such as cardiac imaging, suffer from blurring and artifacts due to the motion of the beating heart, despite advancements in multi-slice scanners and gantry rotation speeds, indicating a need for improved motion-compensated reconstruction methods.
Innovation Solution
A computed tomography system incorporating a motion calculator and reconstructor that processes energy-resolved projection data to generate image data indicative of an object's motion states, allowing for motion compensation during data acquisition and reconstruction, utilizing energy-resolving detectors and k-edge imaging techniques to enhance image clarity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If faster gantry rotation speeds are used to improve temporal resolution, then scan time is reduced, but motion artifacts and blurring increase due to heart motion
Solution Approach 1:
The system performs preliminary actions by acquiring projection data at multiple energy levels before reconstruction, then uses this energy-resolved data to estimate object motion and calculate motion compensation parameters before generating the final motion-compensated images. This preliminary data collection and processing enables the system to correct for heart motion artifacts while maintaining fast scan speeds.
Solution Approach 2:
The invention changes physical parameters by acquiring projection data across multiple energy levels (energy-resolved detection) rather than using conventional single-energy detection. This parameter change enables the system to distinguish between different materials (such as contrast agent and tissue) and to estimate object motion more accurately, thereby reducing motion artifacts while maintaining fast scanning.
2Productivity
If multi-slice CT with increased axial coverage is used, then throughput is improved, but motion compensation capability deteriorates
Solution Approach 1:
The system segments the projection data by energy level, acquiring and processing data at multiple distinct energy levels separately. This segmentation allows the motion estimation algorithm to analyze the attenuation differences across energy levels to accurately estimate object motion, even in multi-slice CT with increased axial coverage. The segmented energy-resolved data is then used to calculate motion compensation parameters for each slice.
Solution Approach 2:
The invention adds another dimension to the data acquisition by incorporating energy resolution as an additional parameter beyond spatial and temporal dimensions. This energy dimension provides additional information that enables accurate motion estimation and compensation across multiple slices, maintaining motion compensation accuracy while supporting increased axial coverage and throughput.
3Measurement precision
If energy-resolved detection is used to identify substances of interest, then material discrimination is improved, but data processing complexity increases
Solution Approach 1:
The system extracts only the essential information needed for motion estimation from the energy-resolved projection data. Rather than processing all energy-resolved data for all possible material discriminations, the method extracts the specific attenuation differences at different energy levels that are most useful for estimating object motion. This extraction reduces processing complexity while maintaining accurate material discrimination for motion estimation purposes.
Solution Approach 2:
The invention introduces an intermediary step where energy-resolved projection data is first used to generate image data at multiple motion states, which then serves as input for motion estimation. This intermediary representation simplifies the subsequent motion compensation processing by providing pre-processed image data that captures the essential motion information, reducing the overall data processing complexity while maintaining material discrimination accuracy.
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 system effectively reduces motion artifacts by accurately estimating and compensating for object motion, resulting in improved image quality and reduced blurring in cardiac imaging and other applications with moving anatomy.
Implementation Method 1
an x-ray detector which acquires energy resolved projection data. The projection data includes first data indicative of detected x-rays having a first energy and second data indicative of detected x-rays having a second energy
Implementation Method 2
utilizing energy-resolving detectors and k-edge imaging techniques to enhance image clarity
Data Source
AI summary
An imaging system includes an energy resolving detector (20) which generates data indicative of detected radiation having at least first and second energies. The system also includes an energy pre-processor (24), a motion calculator (26), and a reconstructor (22). In one embodiment, the apparatus uses a k-edge imaging technique to perform a motion compensated reconstruction of projection data indicative of an object under examination.