CT Scanning Jacket Layout to Reduce Beam Hardening Artifacts
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Solution Overview
Problem
Existing CT scanning methods face challenges in achieving high-quality scans of complex objects with varying cross-sections, particularly turbine blades, due to beam hardening and concave wall effects, which result in image artifacts and poor contrast.
Innovation Solution
The method involves placing the object in a jacket surrounded by a solid volume or filling material with similar attenuation properties, positioning the jacket and object to minimize thickness variation, and orienting the object to reduce concave wall effects, using a scanning apparatus with rotatable support and oppositely disposed x-ray emitter and receiver units.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the voltage of the x-ray emitting apparatus is increased to improve penetration and reduce beam hardening, then the quality of the scan is improved, but the contrast between different materials is reduced
Solution Approach 1:
The patent applies parameter changes by using a jacket made of material with specific attenuation properties that complement the x-ray energy spectrum. The jacket material is selected to have attenuation characteristics that compensate for the reduced material contrast at higher voltages, maintaining both penetration and differentiation capability
Solution Approach 2:
The jacket acts as an intermediary element between the x-ray source and the object being scanned. It modifies the x-ray beam properties by filtering and shaping the spectrum, thereby improving penetration while preserving material contrast through its specific attenuation characteristics
2Adaptability or versatility
If the object is positioned with varying thickness along the rotation path to match complex geometries, then the scan adapts to the object shape, but the thickness variation causes beam hardening and image artifacts
Solution Approach 1:
The patent applies local quality by using a jacket with spatially varying attenuation properties that are tailored to the specific geometry of the object being scanned. The jacket is designed with different material densities or compositions in different regions to compensate for local thickness variations and eliminate beam hardening effects
Solution Approach 2:
The jacket is designed with an asymmetric configuration that mirrors the asymmetric geometry of the object. This asymmetric design ensures that the attenuation path is balanced throughout the rotation, preventing the thickness variation that causes beam hardening and artifacts
3Reliability
If the object is scanned one part at a time to maintain adequate x-ray penetration, then the scan quality for thick sections is improved, but the scanning time and productivity are reduced
Solution Approach 1:
The patent applies universality by designing a jacket that can accommodate multiple different objects or parts simultaneously in a single scanning setup. The jacket's configuration allows various components to be positioned at optimal orientations, enabling parallel scanning of multiple parts while maintaining adequate x-ray penetration for each
4Loss of information
If the object is rotated through 360 degrees to obtain complete volumetric data, then the completeness of the 3D reconstruction is improved, but the scanning time increases
Solution Approach 1:
The patent applies partial action by demonstrating that a limited angular range of rotation (less than 360 degrees) is sufficient to obtain adequate volumetric data for reconstruction. The jacket's specific geometry and attenuation properties enable high-quality scans with reduced rotation angles, thereby decreasing scanning time while maintaining data completeness
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 significantly improves scan quality by reducing artifacts and enhancing contrast, allowing for efficient scanning of multiple objects simultaneously with optimized scanning parameters.
Implementation Method 1
An x-ray source produces polychromatic x-rays that penetrate a part and form an x-ray image on a detector
Implementation Method 2
The composition of the part may effectively attenuate the CT scanning x-ray beam
Implementation Method 3
The support is rotatable relative to the emitting and receiving elements about an axis of rotation to allow creation of an image from projections each taken at a different relative angle of rotation
Data Source
AI summary
There is provided a method for scanning of an object in a scanning apparatus. The method comprises placing the object into a jacket which surrounds the object or a part of the object to be scanned. The volume of the jacket surrounding the object is solid or filled with a filling material. The jacket is disposed on a support of the scanning apparatus, so that the jacket is positioned between an imaging beam emitting element and an imaging beam receiving element oppositely disposed to either side of the support. The support is rotatable relative to the emitting and receiving elements about an axis of rotation to allow creation of an image from projections each taken at a different relative angle of rotation. The method further comprises operating the scanning apparatus at the multiple relative angles of rotation to produce an image of the object.