X-ray Artifact Reduction via Projection Domain Object Localization

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Solution Overview

Problem

Existing methods are ineffective in correcting artifacts generated by objects outside the reconstruction volume in three-dimensional image data sets reconstructed from X-ray projection images, particularly metal objects that cause artifacts even when partially visible in projection images.

Innovation Solution

The method localizes objects outside the reconstruction volume by generating difference images from measured and forward-projected comparative images, allowing for correction of projection images to reduce artifacts, using techniques like edge detection and iterative reconstruction to improve object localization and segmentation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If objects are segmented in the reconstruction volume to correct artifacts, then artifact correction quality is improved, but this method cannot be applied when objects are located outside the reconstruction volume

Engineering Contradiction:

Improveartifact correction qualityVSAvoidapplicability to objects outside reconstruction volume

Core Design Contradiction:

Measurement precisionVSAdaptability or versatility

Solution Approach 1:

The patent extends the correction approach from the 3D reconstruction volume back to the 2D projection image domain. By localizing objects in projection images and correcting projection data, the method handles objects outside the reconstruction volume that project into the field of view, thus resolving the limitation of volume-based segmentation.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The patent introduces projection images as an intermediary between the raw X-ray data and the final 3D reconstruction. By performing object localization and correction in the projection domain before reconstruction, the method enables artifact correction for objects outside the reconstruction volume while maintaining correction quality.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If standard reconstruction is performed from projection images, then the reconstruction volume is obtained, but artifacts are generated by objects outside the reconstruction volume that are visible in projection images

Engineering Contradiction:

Improvereconstruction completenessVSAvoidartifacts from objects outside reconstruction volume

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent performs object localization and projection data correction before the final 3D reconstruction. By identifying and correcting artifacts in the projection images prior to reconstruction, the method prevents artifacts from objects outside the reconstruction volume from being incorporated into the final image data set.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent extracts and removes the contribution of objects outside the reconstruction volume from the projection images. By localizing these objects and correcting their impact on projection data before reconstruction, the harmful artifacts are eliminated while preserving the reconstruction of the nominal measuring field.

Inventive Principle:

Principle #2Taking out (Extraction)

3Ease of operation

If objects are localized in projection images directly, then correction can be applied, but localization is difficult when objects are only visible in a few projection images

Engineering Contradiction:

Improveobject localization feasibilityVSAvoidobject localization accuracy

Core Design Contradiction:

Ease of operationVSMeasurement precision

Solution Approach 1:

The patent employs an iterative approach where initial object localization estimates are refined through feedback from the reconstruction process. By repeatedly localizing objects, reconstructing images, and refining localization based on reconstructed data, the method improves localization accuracy even for objects visible in only a few projection images.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent replaces direct image-based localization with a hybrid approach using sinogram analysis and iterative reconstruction. By transforming the localization problem into the sinogram domain and using feedback from reconstruction, the method achieves accurate localization despite limited object visibility in individual projection images.

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

This approach effectively reduces artifacts in three-dimensional image data sets by accurately localizing and correcting objects outside the reconstruction volume, enhancing image quality and enabling complete reconstruction of the nominal measuring field.

Implementation Method 1

projection images of an object under examination are recorded with an X-ray recording arrangement

Methodology Applied

Scientific EffectX-ray attenuation: Absorption (EM radiation)

Data Source

PatentUS9554766B2Reducing artifacts in an image data set and X-ray device

Publication Date: 2017.01.31 SIEMENS HEALTHINEERS AG

AI summary

Streak artifacts generated by at least one X-ray attenuating object arranged outside a reconstruction volume in a three-dimensional image data set showing the reconstruction volume are reduced. The reconstruction volume is reconstructed from two-dimensional projection images recorded from different projection directions. The object is localized in the projection images showing the object. To determine corrected projection images for the reconstruction of the image data set, the image data of the area of each projection image showing the object is corrected to remove the object. The localization of the object is performed taking into account difference images of the measured projection images and from a reconstruction data set of forward-projected comparative images reconstructed from the measured projection images.