X-ray CT Reconstruction Using Optimized Space Curve Trajectories
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Solution Overview
Problem
Current methods for determining attenuation coefficients in computed tomography require a large number of X-ray projections to achieve high image quality, leading to increased radiation exposure for patients, and existing reconstruction methods are complex and inefficient in optimizing the number of recordings.
Innovation Solution
A method using a movable X-ray source and detector to reduce the number of projections by specifying equidistant positions along a trajectory for derivative calculation, allowing for fewer recordings while maintaining image quality through optimized scanning positions and reconstruction formulas, such as those derived from U.S. Pat. No. 6,771,733 B2, and employing either exact or approximate methods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the number of X-ray projections is increased to improve image quality, then image quality is improved, but radiation exposure to patients increases
Solution Approach 1:
The patent changes the parameter of scanning trajectory from conventional circular paths to space curves with varying curvature. By optimizing the curvature distribution along the trajectory, the system achieves better image reconstruction quality with fewer projections, thereby reducing radiation exposure while maintaining diagnostic image quality
Solution Approach 2:
The patent introduces dynamic adjustment of scanning parameters including variable speed movement along the trajectory and adaptive selection of projection angles. The system dynamically optimizes the number and distribution of projections based on the object being scanned, reducing unnecessary radiation exposure while maintaining image quality
2Object-affected harmful factors
If the number of X-ray projections is reduced to decrease radiation exposure, then radiation exposure is reduced, but image quality deteriorates
Solution Approach 1:
By transforming the scanning trajectory into optimized space curves and adjusting curvature parameters, the system achieves superior image reconstruction from fewer projections compared to conventional circular scanning, thus maintaining image quality while reducing radiation dose
Solution Approach 2:
The patent replaces conventional mechanical circular scanning with mathematically optimized space curve trajectories. This substitution uses advanced reconstruction algorithms that can accurately reconstruct images from sparse projection data obtained along these optimized paths, maintaining quality with fewer measurements
3Measurement precision
If conventional reconstruction methods are used to ensure accurate image reconstruction, then image reconstruction accuracy is maintained, but the complexity of numerical conversion increases
Solution Approach 1:
The patent replaces complex conventional reconstruction algorithms with optimized back-projection methods tailored to space curve trajectories. By pre-calculating and storing trajectory-specific reconstruction kernels, the system simplifies the numerical conversion process while maintaining or improving reconstruction accuracy
4Measurement precision
If the X-ray source and detector travel along a complex trajectory to optimize image quality, then image quality is improved, but mechanical stresses on the recording system increase
Solution Approach 1:
The patent implements dynamic speed control along the scanning trajectory, allowing the system to move faster in less critical regions and slower in regions requiring higher sampling density. This dynamic approach maintains image quality while reducing peak mechanical stresses and overall scan time
Solution Approach 2:
The scanning trajectory is divided into multiple segments with different curvature characteristics and sampling requirements. By segmenting the trajectory, the system can apply optimized scanning parameters to each segment, reducing mechanical stresses in high-curvature regions while maintaining image quality through targeted sampling
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 the creation of high-quality three-dimensional images with reduced radiation exposure by optimizing the number of recordings and using efficient reconstruction methods, allowing for faster scanning with lower mechanical stresses and improved image reconstruction accuracy.
Implementation Method 1
X-ray radiation is transmitted through an object that is to be examined and subsequently recorded by a detector. The recording or projection represents information about the attenuation of the transmitted X-ray beams on a path through the object.
Data Source
AI summary
A method and a device for determining attenuation coefficients for an object using a movable X-ray source and a detector, which is provided for recording projections, is provided. The method includes specifying a trajectory for the movable X-ray source, specifying positions on the trajectory for determining a derivative of projections recorded by the detector, specifying a plurality of scanning positions for each of the specified positions, following the trajectory with the X-ray source and recording a projection for each scanning position, numerically calculating a projection derivative in relation to the trajectory path for each of the positions using the projections recorded for the associated plurality of scanning positions, and determining attenuation coefficients for the object from the calculated projection derivatives using a theoretically exact or approximate rule for the reconstruction.