Pulsed X-ray Emission for Low-Dose CT Imaging
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Solution Overview
Problem
X-ray computed tomography (CT) scans, particularly dynamic CT scans like CT perfusion and CT angiography, expose patients to high radiation doses due to continuous X-ray source operation, posing a significant concern for patient safety and long-term health.
Innovation Solution
A low-dose CT imaging system that employs a pulsed X-ray emission scheme based on a predefined sequence of rotation angles of the X-ray source, combined with advanced image reconstruction algorithms, to reduce radiation exposure while maintaining high spatial and temporal resolution, using techniques such as angle-bisect, golden-ratio, and pseudo-random schemes for optimized projection acquisition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If continuous X-ray emission is used during CT scanning, then image quality and temporal resolution are maintained, but radiation dose to the patient increases significantly
Solution Approach 1:
The patent applies periodic action by switching the X-ray source on and off at predetermined intervals during gantry rotation. Instead of continuous emission, X-rays are emitted only at specific angular positions (e.g., every 45 degrees), creating a pulsed emission pattern that reduces cumulative radiation exposure while still capturing sufficient projection data at critical angles to maintain temporal resolution for dynamic imaging.
Solution Approach 2:
The patent segments the continuous X-ray emission into discrete angular segments or bursts. The full 360-degree rotation is divided into multiple segments where X-ray emission occurs only during specific angular ranges rather than continuously throughout the entire rotation, allowing the system to acquire necessary projection data while minimizing total radiation dose.
2Object-affected harmful factors
If fewer projection views are acquired to reduce radiation dose, then radiation exposure decreases, but image reconstruction quality and spatial resolution deteriorate
Solution Approach 1:
The patent changes the angular distribution parameters of projection views rather than simply reducing the total number uniformly. By optimizing which specific angular positions are sampled and how the limited views are distributed across the rotation, the system achieves adequate image reconstruction quality from fewer projections. The reconstruction algorithm parameters are also adapted to handle the sparse sampling pattern effectively.
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 achieves a 4-8 fold reduction in radiation dose compared to standard CT scans without degrading image quality, making previously infeasible body CT perfusion scans possible and allowing for more frequent patient monitoring.
Implementation Method 1
an X-ray source mounted on a gantry so as to rotate within a cylindrical enclosure of the CT scanner
Data Source
Figure 1~2
Figure 3
Figure 4A~4C
AI summary
A low-dose CT imaging system and method that operates according to a pulsed X-ray emission scheme according to a predefined sequence of rotation angles of the X-ray source, along with image reconstruction algorithms to achieve high spatial and temporal resolution for CT scans. The systems and methods involve high speed switching (on the order of milliseconds) to generate pulsed exposure of X-ray radiation to the patient, reducing radiation dose by 4-8 fold, or more.