CT Artifact Removal via Spatial Frequency Extraction
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Solution Overview
Problem
CT imaging systems face artifacts due to off-focal radiation, which increase radiation dose and cause image inconsistencies, particularly affecting medical imaging by introducing shading and blooming artifacts that vary with object location and distance from the x-ray focal spot.
Innovation Solution
The system includes a CT acquisition unit with an X-ray source and detector configured to rotate and translate relative to the object, with a processor that extracts spatial frequency information and removes periodically recurring artifacts based on longitudinal collection periodicity, providing a corrected image.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If off-focal radiation is present in CT imaging, then radiation dose to patient increases, but image quality deteriorates due to artifacts
Solution Approach 1:
The patent extracts and removes off-focal radiation components from the detected X-ray signals through data processing. The system identifies and eliminates radiation contributions from non-focal spot sources before image reconstruction, thereby reducing artifact formation while maintaining acceptable radiation dose levels.
Solution Approach 2:
The patent applies calibration factors and correction parameters to adjust the detected radiation data. By modifying the data parameters through calibration procedures and computational corrections, the system compensates for off-focal radiation effects and reduces resulting artifacts in the final image.
2Quantity of substance
If off-focal radiation is present, then photon counts at detector are erroneously elevated, but this creates data inconsistency and image artifacts
Solution Approach 1:
The patent implements a feedback mechanism where the system detects elevated photon counts, identifies them as potentially erroneous due to off-focal radiation, and applies corrective processing. The calibration and correction algorithms use feedback from the detected signal characteristics to adjust and correct the data, ensuring consistency and eliminating artifacts.
3Reliability
If traditional calibration and correction methods are used, then some artifact reduction is achieved, but shading and blooming artifacts persist
Solution Approach 1:
The patent performs preliminary calibration and correction actions before final image reconstruction. By pre-processing the raw detection data to remove off-focal radiation components and apply correction factors beforehand, the system prevents shading and blooming artifacts from forming in the final image, achieving superior artifact reduction compared to post-processing methods.
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 or eliminates artifacts caused by off-focal radiation, minimizing radiation dose and image inconsistencies, while reducing hardware calibration costs and addressing recurring artifacts independently of scanner type or vendor.
Implementation Method 1
an X-ray source and a CT detector configured to collect CT imaging data of an object to be imaged. The object includes an acquisition volume comprising a cross-section extending along a longitudinal direction. The X-ray source and CT detector are configured to be rotated relative to the object to be imaged and to collect a series of projections of the object
Data Source
AI summary
An imaging system includes a computed tomography (CT) acquisition unit and at least one processor. The CT acquisition unit includes an X-ray source and a CT detector configured to collect CT imaging data of an object to be imaged. The at least one processor is operably coupled to the CT acquisition unit, and is configured to reconstruct an image using the CT imaging information; extract spatial frequency information from at least a portion of the image, wherein the spatial frequency is defined along a longitudinal direction; and remove a periodically recurring artifact from the at least a portion of the image based on a spatial frequency corresponding to a longitudinal collection periodicity to provide a corrected image.