Helical CT Motion Map Generation via Complementary Rays
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Solution Overview
Problem
Current methods for generating cardiac phase maps in coronary CT scans are inefficient, inaccurate, and result in high x-ray exposure, as they fail to consistently determine optimal cardiac phases due to patient variability and assume uniform heart movement, leading to artifacts in reconstructed images.
Innovation Solution
The method involves generating a motion map using helically scanned data and complementary rays to select projection data with minimal movement, reducing x-ray exposure and artifacts by calculating the Sum of Absolute Differences (SAD) and filtering and shifting the data to construct an accurate motion map.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If prior art selection techniques are used to determine optimal cardiac phase, then the phase selection can be completed, but the selection time accounts for a large percentage of the examination time
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing motion compensation data during the helical scanning process. Instead of performing time-consuming image reconstruction and phase selection after scanning, the system computes motion maps and identifies optimal cardiac phases in real-time during data acquisition, thereby reducing post-scan processing time and overall examination duration.
2Measurement precision
If image domain techniques are used to determine optimal cardiac phase, then phase selection can be performed, but the reconstruction calculation is time-consuming
Solution Approach 1:
The patent extracts the motion analysis function from the traditional image reconstruction domain and implements it directly in the projection data domain. By computing motion maps and SAD values from raw projection data without requiring intermediate image reconstruction, the system maintains measurement precision while eliminating the time-consuming reconstruction step.
3Device complexity
If uniform heart movement assumption is made, then the complex nature of heart movement is simplified, but the assumption does not accurately reflect actual cardiac motion
Solution Approach 1:
The patent applies local quality by computing motion analysis separately for different regions of the heart using region-specific projection data. Instead of assuming uniform motion across the entire heart, the system calculates motion maps for specific cardiac chambers and regions independently, allowing each local area to have its own motion characteristics accurately captured.
4Measurement precision
If low pitch helical scan is used, then accurate phase selection can be achieved, but x-ray exposure to patient increases
Solution Approach 1:
The patent changes the pitch parameter from traditional low pitch values to higher pitch values (up to 2.0 or more) while maintaining phase selection accuracy through real-time motion map computation. The system adjusts scanning parameters to reduce patient exposure and implements adaptive pitch control that maintains measurement precision despite the parameter change.
Data Source
AI summary
As an illustration of generating a motion map, although the cardiac CT is described for selecting an optimal phase, the disclosure is not limited to the cardiac CT. For the cardiac CT, the cardiac phase map is efficiently generated based upon helical scan data, and the optimal phase is selected within a reasonable time. At the same time, the optimal phase is accurately determined based upon complementary rays as indexes for minimal movement so as to select the projection data for minimizing artifacts in reconstructed cardiac images. The helically scanned data reflect motion within the same cardiac cycle or over the continuous cardiac cycles. The application of the complementary ray technique to the helically scanned data is accomplished by three-dimensionally determining a pair of the complementary rays in order to take into account motion within the same cardiac cycle or over the continuous cardiac cycles. The absolute sum of the differences for the top ray and or the bottom ray is determined in order to determine the amount of cardiac motion.