Variable Thickness CT Filter for X-ray Attenuation
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Solution Overview
Problem
Computed tomography (CT) scanning devices face challenges in achieving uniform energy distribution and optimal X-ray attenuation for different examination regions and projection angles, leading to suboptimal image quality and increased radiation dose.
Innovation Solution
A filter set with a disc having an annular groove structure, where the body thickness varies in the circumferential and radial directions, is integrated into the CT scanning device. This filter set is connected to a drive shaft and rotates with the gantry, allowing for precise alignment of the filter regions with the X-ray beam, ensuring appropriate X-ray attenuation based on the examination region and projection angle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a filter with uniform thickness is used, then the device complexity is low, but the energy distribution uniformity and image quality deteriorate
Solution Approach 1:
The filter employs varying thickness across different regions to provide locally optimized X-ray attenuation. The filter thickness is specifically designed to vary in the radial direction (thicker at edges, thinner at center) and/or circumferential direction (different thicknesses for different angular positions) to compensate for the varying path lengths through the patient's body at different projection angles, thereby achieving uniform energy distribution and improved image quality
Solution Approach 2:
The filter transitions from a simple planar structure to a three-dimensional variable thickness structure. By introducing thickness variation as an additional degree of freedom in the filter design, the system can achieve complex attenuation patterns that match the geometric requirements of CT scanning at different angles and positions, resolving the contradiction between structural simplicity and performance optimization
2Adaptability or versatility
If a fixed filter configuration is used, then the device complexity is low, but the adaptability to different examination regions and projection angles deteriorates
Solution Approach 1:
The filter is designed with spatially varying thickness characteristics that provide different attenuation properties at different locations. This local optimization enables the single filter structure to adapt to various examination regions (head, chest, abdomen, etc.) and projection angles by presenting the appropriate thickness profile to the X-ray beam without requiring multiple interchangeable filters
Solution Approach 2:
The variable thickness filter serves multiple functions simultaneously: it compensates for geometric attenuation at different projection angles, adapts to different examination regions, and maintains uniform energy distribution. This multi-functionality is achieved through a single integrated filter structure rather than multiple specialized components, thereby improving adaptability while controlling overall device complexity
3Manufacturing precision
If no filter is used, then the radiation dose to the patient is low, but the image quality deteriorates due to low-energy rays having no positive effect
Solution Approach 1:
The filter utilizes changes in material thickness as a controllable parameter to selectively attenuate low-energy X-rays. By optimizing the thickness distribution, the filter removes harmful low-energy radiation that does not contribute to image formation while preserving the useful higher-energy photons, thereby improving image quality and reducing patient radiation dose simultaneously
Solution Approach 2:
The filter transforms the potentially harmful effect of low-energy X-rays (which increase radiation dose without improving image quality) into a beneficial outcome. By selectively attenuating these low-energy photons, the filter converts what would be wasted radiation into improved image quality and reduced unnecessary patient exposure, achieving better signal-to-noise ratio in the detected X-ray signals
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 solution enhances CT image quality by optimizing X-ray intensity distribution, reducing radiation dose, and improving scan efficiency by aligning the filter regions with specific X-ray attenuation requirements for various examination areas and angles.
Implementation Method 1
it may dispose a filter between an X-ray source and a patient's examination region to filter out low-energy rays that have no positive effect for reconstructing a CT image
Data Source
AI summary
A filter set of a CT scanning device and control method thereof are provided. An example of the CT scanning device includes a gantry, an X-ray generator, a filter set, a detector, and a drive motor. The filter set includes a disc, a filter disposed on the disc and having a substantially annular groove structure, and a drive shaft connected to the disc. A body thickness of the annular groove structure varies in a circumferential direction and a radial direction. A shaft axis of the drive shaft is parallel to a radiation direction of X-ray. As the drive shaft is driven by the drive motor, the disc rotates around the shaft axis, such that a region of the filter is aligned with the radiation direction of the X-ray, and a body thickness of the region corresponds to a respective X-ray attenuation for an examination region of a subject.