projection-based metal-artifact reduction for industrial 3d x-ray computed tomography

Projection-Based Metal-Artifact Reduction for Industrial 3D X-ray

Computed TomographyArtem Amirkhanov 1,2

Michael Reiter 2

Johann Kastner 2

Christoph Heinzl 2

M. Eduard Gröller 1

1 Institute of Computer Graphicsand Algorithms

Vienna University of Technology

2 Upper Austrian University of Applied Sciences

Wels Campus, Austria

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Scanning Geometry

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Scanning Geometry

X-ray sourceSpecimen

Detector

Rotary plate

Projections 3D VolumeReconstruction

Multi-Material Components (MMCs)

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Most industrial parts are MMCsMaterials:

AirPlasticMetal

Metal Artifacts

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Appear in MMCsMetal artifacts

Dark-band artifactsStreak-noise artifacts

Caused by beam hardeningBad for

Material characterization Measurements

Dark-band artifacts

Streak-noise artifacts

Our Contributions

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Adaptation of a projection-based metal artifacts reduction (MAR) workflow for 3DXCTIntegrated visual analysis tool

MAR Workflow

Integrated VA Tool

Main Idea

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Artifacts source: projectionsWe remove metal from projectionsWe then reconstruct the 3D volume with reduced artifactsWe insert the metal back into this volume

Streak-noise artifacts

Initial Data

Initial Reconstruction3D Volume

Metal3D Volume

Without MetalProjections

Metal InterpolatedProjection

MAR Volume3D VolumeOutput

Reconstruction

Material Separation

Forward Projection

Interpolation

Fusion

Wor

kflo

w

MAR without Metal3D Volume

Reconstruction

Projections

Projections 3D Volume

InputMAR Workflow

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Attenuation coefficient thresholding

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Material Separation

Initial Data

Initial Reconstruction3D Volume

Metal3D Volume

Without MetalProjections

Metal InterpolatedProjection

MAR Volume3D Volume

Input

Output

Reconstruction

Material Separation

Forward Projection

Interpolation

Fusion

Wor

kflo

w

MAR without Metal3D Volume

Reconstruction

Projections

Projections 3D Volume

MAR Workflow

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Forward ProjectionWorks as follows:

Project every metal voxel on every projection

X-ray sourceSpecimen

Projection

Rotary plate

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Forward Projection

Projection

Metal voxel projectionVoxel center

Length of projected voxel diagonal

Covered pixels

Partially covered pixelsWe overestimate partially covered pixels

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Initial Data

Initial Reconstruction3D Volume

Metal3D Volume

Without MetalProjections

Metal InterpolatedProjection

MAR Volume3D Volume

Input

Output

Reconstruction

Material Separation

Forward Projection

Interpolation

Fusion

Wor

kflo

w

MAR without Metal3D Volume

Reconstruction

Projections

Projections 3D Volume

MAR Workflow

3D Volume Metal

Forward Projection

Initial Data

Initial Reconstruction3D Volume

Metal InterpolatedProjection

MAR Volume3D Volume

Input

Reconstruction

Material Separation

Interpolation

Fusion

Wor

kflo

w

MAR without Metal3D Volume

Reconstruction

Projections

3D Volume

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Without MetalProjections

MAR Workflow

Projections

Output

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Interpolation

Row-wise linear interpolation along the X axis

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Interpolation

Row-wise linear interpolation along the X axis

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Interpolation

Row-wise linear interpolation along the X axis

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Interpolation

Row-wise linear interpolation along the X axis

Start of the gap End of the gap

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Interpolation

Row-wise linear interpolation along the X axis

Start of the gap End of the gap

Initial Data

Initial Reconstruction3D Volume

Metal3D Volume

Without MetalProjections

Metal InterpolatedProjection

MAR Volume3D Volume

Input

Output

Reconstruction

Material Separation

Forward Projection

Interpolation

Fusion

Wor

kflo

w

MAR without Metal3D Volume

Reconstruction

Projections

Projections 3D Volume

MAR Workflow

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Initial Data

Initial Reconstruction3D Volume

Metal3D Volume

Without MetalProjections

Metal InterpolatedProjection

MAR Volume3D Volume

Input

Output

Reconstruction

Material Separation

Forward Projection

Interpolation

Fusion

Wor

kflo

w

MAR without Metal3D Volume

Reconstruction

Projections

3D Volume

MAR Workflow

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Fusion

Interpolation on the metal boundaries for smooth appearance

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Integrated Visual Analysis Tool

Steps of the workflow are integratedVisual threshold estimation

Segmentation previewResult preview

Visual result exploration

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Results (1)

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Results (1)

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Results (2)

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Results (2)

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Results (3)

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Results (3)

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Limitations

Interpolation introduces blurring in the result Limiting factor: metal projected area

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Limitations

Interpolation introduces blurring in the result Limiting factor: metal projected area

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Conclusions

MAR for 3D industrial MMCsSignificant artifact reductionWorks for various datasets

Integrated visual analysis toolAssisting user in threshold estimationExploring the result

GPU implementation (CUDA)ReconstructionForward-projectionInterpolation

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Conclusions

Thank you!

VS

Contact: artem@cg.tuwien.ac.at