X-ray CT Helical Scan with Variable Pitch for Cardiac Imaging
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Solution Overview
Problem
Current X-ray CT imaging methods face challenges in achieving low radiation exposure and high-speed, high-quality cardiac imaging due to limitations in helical pitch, leading to artifacts and incomplete coverage of the heart with conventional scans.
Innovation Solution
An X-ray CT apparatus with a multi-row or two-dimensional X-ray area detector system that performs helical scans with a variable pitch, synchronized with electrocardiographic signals to acquire X-ray projection data efficiently, allowing for improved image reconstruction and reduced radiation dosage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a slow helical pitch (0.2) is used for cardiac imaging, then the imaging coverage is sufficient, but the radiation exposure increases and imaging speed decreases
Solution Approach 1:
The patent applies segmentation by dividing the heart imaging process into multiple segments along the z-axis. Each segment is imaged with a faster helical pitch, and the segments are later reconstructed together to form the complete heart image. This allows sufficient coverage while reducing radiation exposure in each individual scan segment.
Solution Approach 2:
The patent employs dynamic pitch adjustment where the helical pitch varies during the scan. The pitch is optimized for different z-axis positions to balance coverage and radiation dose. This dynamic approach allows faster imaging speed in critical regions while maintaining adequate coverage throughout the entire heart volume.
2Volume of moving object
If a slow helical pitch (0.2) is used for cardiac imaging, then the imaging coverage is sufficient, but the imaging speed decreases
Solution Approach 1:
By segmenting the heart into multiple imaging zones along the z-axis, each segment can be scanned more quickly with a higher pitch. The segmented approach maintains overall coverage while significantly improving imaging speed compared to a single slow-pitch scan of the entire heart.
Solution Approach 2:
The patent maintains continuous data acquisition throughout the helical scan, ensuring that the X-ray beam continuously covers the heart volume. This continuous action, combined with multi-segment reconstruction, achieves fast imaging without sacrificing coverage.
3Adaptability or versatility
If multi-segment image reconstruction is used to adapt to various heartbeats, then adaptability improves, but image quality deteriorates due to artifacts
Solution Approach 1:
The patent performs preliminary synchronization with the electrocardiographic signal before acquiring projection data. By timing the scan to specific phases of the cardiac cycle, the system captures images at optimal moments, reducing motion artifacts and improving image quality while maintaining adaptability to various heart rates.
Solution Approach 2:
The system uses feedback from electrocardiographic monitoring to adjust the imaging timing and reconstruction parameters. This feedback mechanism ensures that images are reconstructed from data acquired at appropriate cardiac phases, minimizing artifacts while adapting to different heartbeat characteristics.
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
Enables low-dose, high-speed cardiac imaging with reduced artifacts and complete heart coverage, enhancing image quality and reducing radiation exposure.
Implementation Method 1
an X-ray generator and an X-ray detector having a two-dimensional detection plane and detecting X rays in opposition to the X-ray generator
Data Source
AI summary
An X-ray CT apparatus includes an X-ray data acquisition device for acquiring X-ray projection data transmitted through a subject lying between an X-ray generator and an X-ray detector having a two-dimensional detection plane and detecting X rays in opposition to the X-ray generator, while the X-ray generator and the X-ray detector are being rotated about a center of rotation lying there between; an image reconstructing device for image-reconstructing the acquired projection data; an image display device for displaying the image-reconstructed tomographic image; and an imaging condition setting device for setting various kinds of imaging conditions for tomographic image, wherein the X-ray data acquisition device acquires X-ray projection data in sync with an external sync signal by a helical scan with a predetermined range of the subject with a helical pitch set to 1 or more.