Fast kVp Switching CT Scatter Artifact Correction
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Solution Overview
Problem
X-ray scatter in CT imaging systems produces artifacts that degrade image quality and resemble beam hardening artifacts, making it difficult to achieve diagnostic accuracy in fast kilovoltage switching computed tomography applications.
Innovation Solution
A method and apparatus that acquire and process high and low peak kilovoltage CT imaging datasets to generate base material images, estimate artifact correlation, and correct these images using a base correction image, thereby reducing scatter-generated artifacts and improving image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fast kVp switching is used to reduce beam hardening artifacts, then image quality is improved, but x-ray scatter artifacts are produced that resemble beam hardening artifacts
Solution Approach 1:
The patent segments the image reconstruction process into multiple steps: acquiring datasets at different kVp levels, generating base material images through decomposition, creating a base correction image, estimating artifact correlation, and applying corrections. This segmentation allows targeted handling of scatter artifacts while preserving the benefits of fast kVp switching.
Solution Approach 2:
The patent introduces a base correction image as an intermediary element that captures scatter artifact information. This correction image serves as a mediator between the raw fast kVp switching data and the final corrected images, allowing scatter artifacts to be identified and removed without compromising the diagnostic quality improvements from fast kVp switching.
2Measurement precision
If base material decomposition is performed to reduce beam hardening artifacts, then diagnostic accuracy is improved, but scatter artifacts remain that degrade image quality
Solution Approach 1:
The patent implements a feedback mechanism where artifact correlation is estimated from the base material images and used to generate corrections that are applied back to the images. This feedback loop continuously refines the images by identifying and correcting scatter artifacts while preserving the diagnostic accuracy achieved through base material decomposition.
Solution Approach 2:
The patent performs preliminary base material decomposition and generates a base correction image before final image reconstruction. This preliminary action allows scatter artifacts to be identified and corrected in advance, preventing them from degrading the final diagnostic quality of the reconstructed images.
3Adaptability or versatility
If two scans are acquired back-to-back sequentially at different energies, then material characterization is improved, but scan time is doubled
Solution Approach 1:
The patent uses periodic action by rapidly alternating the x-ray tube potential between high and low kVp levels during a single gantry rotation. This periodic switching allows acquisition of both high and low energy datasets in an interleaved fashion within the same rotation, achieving dual-energy material characterization without requiring two separate scans and thereby halving the scan time.
Solution Approach 2:
The patent merges the acquisition of high and low energy datasets into a single gantry rotation by rapidly switching kVp levels. This combining of what would traditionally require two separate scans into one unified acquisition process maintains comprehensive material characterization capability while reducing the total scan time by approximately 50%.
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 effectively reduces image artifacts and enhances diagnostic performance by correcting base material images and generating accurate monochromatic images, improving tissue characterization and material discrimination in CT imaging.
Implementation Method 1
two physical processes dominate the x-ray attenuation: (1) Compton scatter and the (2) photoelectric effect
Implementation Method 2
two physical processes dominate the x-ray attenuation: (1) Compton scatter and the (2) photoelectric effect
Implementation Method 3
a scintillator for converting x-rays to light energy adjacent the collimator, and photodiodes for receiving the light energy from the adjacent scintillator and producing electrical signals therefrom
Data Source
AI summary
A CT system includes a generator configured to energize an x-ray source to a first kilovoltage (kVp) and to a second kVp, and a computer that is programmed to acquire a first view dataset with the x-ray source energized to the first kVp and a second view dataset with the x-ray source energized to the second kVp, generate a base correction image using the first view dataset and the second view dataset, and reconstruct a pair of base material images from the first view dataset and from the second view dataset. The computer is also programmed to estimate artifact correlation in the pair of base material images using the base correction image, generate a pair of final base material images and a final monochromatic image, and correct one of the pair of final base material images and the final monochromatic image at a keV value using the estimated artifact correlation.