Interleaved Multi-Energy CT Image Reconstruction

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Solution Overview

Problem

Interleaved multi-energy imaging acquisitions in CT scans lead to angular undersampling, resulting in artifacts such as streaks and moiré patterns due to fewer projections, which degrade image quality.

Innovation Solution

A method and system that determine and correct for divergent gradient locations between image scans acquired at different kVp settings by tagging them as undersampling artifacts, using a reconstructor to generate artifact-free images by ensuring gradient locations match across scans.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of time

If interleaved multi-energy imaging acquisitions are used, then scan time and x-ray dose are reduced, but angular undersampling occurs leading to artifacts such as streaks and moiré patterns

Engineering Contradiction:
Improvescan timeVSAvoidimage quality
Core Design Contradiction:
Loss of timeVSReliability

Solution Approach 1:

The patent converts the harmful undersampling artifacts into detectable features by identifying divergent gradient locations between different energy scans. These artifacts, which normally degrade image quality, are systematically located and corrected through gradient analysis, transforming the problem into a solvable pattern recognition task that removes artifacts while preserving the benefits of interleaved acquisition

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The patent changes the parameter being analyzed from raw projection data to gradient locations in reconstructed images. By transforming the data representation and focusing on gradient characteristics rather than direct projection values, the method enables artifact identification and correction, improving image quality while maintaining the time-efficient interleaved acquisition approach

Inventive Principle:
Principle #35Parameter changes

2Productivity

If fewer projections are used in interleaved acquisition, then productivity increases, but manufacturing precision of the image reconstruction deteriorates due to undersampling artifacts

Engineering Contradiction:
Improveacquisition speedVSAvoidreconstruction accuracy
Core Design Contradiction:
ProductivityVSManufacturing precision

Solution Approach 1:

The patent replaces the mechanical requirement of acquiring complete projection sets with a computational gradient analysis system. Instead of mechanically increasing the number of projections to improve precision, the method uses gradient location comparison between scans to identify and correct artifacts, substituting physical acquisition requirements with computational processing

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

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

Significantly reduces or eliminates undersampling artifacts, resulting in more reliable and high-quality images by accurately identifying and correcting for divergent gradient locations.

Implementation Method 1

a kVp-switched x-ray source generating x-rays at a first kVp and a second kVp

Methodology Applied
Scientific EffectX-ray generation: X-Ray

Implementation Method 2

an x-ray detector for detecting x-rays generated at the first kVp and at the second kVp that have traversed an examination region

Methodology Applied
Scientific EffectX-ray detection: Photoelectric Effect

Data Source

PatentEP2864964B1Image reconstruction in interleaved multi-energy imaging
Publication Date: 2019.08.07 PHILIPS GMBH
  • EP2864964B1 patent drawingFigure 1
  • EP2864964B1 patent drawingFigure 2a~2d
  • EP2864964B1 patent drawingFigure 3a

AI summary

The present invention discloses a method for reconstructing an image obtained from kVp switched imaging of a body by acquiring a plurality of images at a first kVp defining a first image scan and a plurality of images at a second kVp defining a second image scan, wherein the plurality of images at the first kVp are acquired interleaved with the plurality of images of the second image scan and by reconstructing an image from the first and second image scan, comprising determining at least one gradient location for at least two images in the first and second image scans, determining divergent gradient locations in respect of a same part of the body for said at least two images in the first and second image scans, tagging each divergent gradient location as an under sampling artifact, generating the reconstructed image from the at least two images in the first and second image scans by correcting for each tagged under sampling artifact. The invention further discloses an imaging system for imaging at least a part of a body by means of a first image scan and a second image scan and a computer program product.