CT System Spectral Projection Decomposition for Contrast Balancing
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Solution Overview
Problem
Computed tomography systems face challenges in generating high-quality images of subjects with contrast agents due to changing distribution over time, leading to image artifacts from varying concentrations.
Innovation Solution
A computed tomography system and method that acquire and decompose spectral projections into sets indicative of contrast agents and non-contrast agents, allowing for scaling and reconstruction to balance contrast agent amounts, improving image quality by using spectral projections and cardiac gating to reduce artifacts and radiation dose.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If spectral projections are acquired at different positions along the rotation axis, then image quality can be improved through scaling and balancing, but the complexity of the reconstruction process increases
Solution Approach 1:
The spectral projections are divided into multiple sets corresponding to different positions along the rotation axis. Each set is processed independently through decomposition and scaling operations, allowing the complex reconstruction to be broken down into manageable segments that can be handled systematically
Solution Approach 2:
The invention applies scaling factors to the spectral projections based on determined contrast values, effectively changing the parameters of the projection data to balance contrast agent amounts across different positions. This parameter transformation simplifies the final reconstruction by pre-normalizing the data
2Measurement precision
If contrast agent distribution changes over time during scanning, then accurate imaging becomes difficult, but extending scan time increases radiation exposure
Solution Approach 1:
The invention performs preliminary decomposition of spectral projections into contrast agent-specific components before reconstruction. By identifying and isolating the contrast agent signal in advance, the system can accurately track and compensate for temporal changes in contrast distribution, enabling precise imaging without requiring extended scan times
Solution Approach 2:
The invention replaces traditional mechanical approaches of simply extending scan duration with a computational approach using spectral decomposition and scaling. This substitution allows the system to handle temporal variations through data processing rather than physical measurement extension, reducing radiation exposure
3Manufacturing precision
If spectral decomposition is performed to separate contrast agent signals, then image quality improves, but the processing time and computational load increase
Solution Approach 1:
The decomposition process is segmented into distinct steps: separating contrast agent-specific projections from other signals, determining contrast values for each position, calculating scaling factors, and applying corrections. This segmentation allows each step to be optimized independently and facilitates parallel processing where applicable
Solution Approach 2:
The invention applies local quality by determining contrast values and scaling factors specific to each position along the rotation axis. This localized approach allows processing to be focused on relevant regions with varying contrast distribution, rather than uniformly processing all data, thereby reducing overall computational load
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 method enhances image quality by balancing contrast agent amounts and reducing artifacts, particularly in cardiac imaging, while minimizing radiation exposure.
Implementation Method 1
a radiation source emitting radiation traversing a subject to be imaged and a detector for generating detection values depending on the radiation having traversed the subject
Data Source
AI summary
The invention relates to a computed tomography system (30). Several sets of spectral projections, which correspond to different positions of a radiation source (2) along a rotation axis (R), are decomposed into first projections being indicative of a contrast agent and second projections being not indicative of the contrast agent. An image is generated by a) determining for each first projection a contrast value being indicative of a total amount of contrast agent and scaling the first projections such that for different first projections of a same set the same contrast value is determined, and reconstructing an image based on the scaled first projections, and/or b) reconstructing for the different sets first images, scaling the first images such that they have a same intensity in overlap regions and combining the scaled first images. Thus, different contrast agent amounts can be balanced, thereby allowing for an improved image quality.