Bell-Shaped Collimator Plates for CT Imaging
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Solution Overview
Problem
Computed tomography (CT) imaging systems suffer from aliasing artifacts due to the rectangular transition profile of post-patient collimators, which leads to high frequency components wrapping around and reducing image quality.
Innovation Solution
The use of a post-patient collimator with bell-shaped plates and non-uniform transition profiles, aligned with inactive regions of the detector, to reduce aliasing artifacts by pre-filtering signals in the spatial domain before digitization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a post-patient collimator with rectangular transition profile is used, then scattered X-rays are blocked and noise is reduced, but high frequency components wrap around and form aliasing artifacts in the final CT images
Solution Approach 1:
The patent applies curvature to the collimator plates by using bell-shaped profiles instead of rectangular ones. The bell-shaped collimator plates have curved transition regions that smoothly modulate the X-ray beam, preventing the sharp edges that cause high frequency components to wrap around. This curvature-based design eliminates aliasing artifacts while maintaining the noise reduction function of the collimator.
Solution Approach 2:
The patent changes the geometric parameters of the collimator plates from rectangular to bell-shaped profiles. By modifying the shape parameters (transitioning from straight edges to curved surfaces), the system alters the spatial frequency content of the beam modulation, thereby preventing aliasing artifacts while maintaining adequate noise suppression.
2Manufacturing precision
If additional measures like focal spot wobble or post-processing are used to reduce aliasing artifacts, then image quality improves, but device complexity and processing time increase
Solution Approach 1:
The patent performs the aliasing prevention action in advance by designing the collimator plates with bell-shaped profiles before the X-ray imaging process. This preliminary design choice prevents aliasing artifacts from forming in the first place, eliminating the need for subsequent corrective measures like focal spot wobble or post-processing algorithms, thereby reducing overall system complexity.
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 effectively reduces aliasing artifacts in CT images without the need for additional measures like focal spot wobble or post-processing, improving image quality by minimizing high frequency components.
Implementation Method 1
a collimator positioned between the patient and the X-ray detector and configured to non-uniformly attenuate the X-rays
Data Source
AI summary
A collimator is provided for reducing aliasing artifacts in images generated in an X-ray imaging system, such as a computed tomography (CT) imaging system. In one embodiment, a collimator comprises a plurality of high attenuating regions interleaved with a plurality of low attenuating regions, with each high attenuating region having a non-uniform transition profile and configured to be aligned with a respective inactive region of a respective channel of an X-ray detector of an X-ray imaging system. In another embodiment, a CT imaging system, comprising an X-ray source configured to project X-rays towards a patient; an X-ray detector configured to receive attenuated X-rays passing through the patient; and a collimator positioned between the patient and the X-ray detector and configured to non-uniformly attenuate the X-rays, the collimator having bell shaped plates, each of the plates separated by a gap.