Cone beam volume CT image artifacts caused by defective cells in x-ray flat panel imagers and the artifact removal...

Area of Science:

• Medical Imaging
• Biomedical Engineering
• Signal Processing

Background:

• X-ray flat panel imagers (FPIs) are crucial for cone beam volume CT (CBVCT).
• Manufacturing defects in FPIs lead to abnormal pixels, causing streak and ring artifacts in CBVCT reconstructions.
• Artifacts in 3D CBVCT differ from 2D CT due to 3D back-projection.

Purpose of the Study:

• To analyze the geometric propagation of pixel abnormalities in 3D CBVCT back-projection.
• To investigate the morphology of streak and ring artifacts caused by defective FPI cells.
• To propose and evaluate a novel method for correcting abnormal pixels and mitigating artifacts in CBVCT.

Main Methods:

• Geometric analysis of abnormality propagation in 3D back-projection.
• Computer simulations and phantom studies to investigate artifact morphology.
• A 2D wavelet-analysis-based statistical approach for abnormal pixel correction, including template acquisition and interpolation/filtering.

Main Results:

• The proposed wavelet analysis method reliably identifies and corrects defective pixels in FPIs.
• Streak and ring artifacts in CBVCT images were effectively eliminated.
• The correction approach demonstrated robustness across variable x-ray exposure levels (30-70% of dynamic range).

Conclusions:

• The developed 2D wavelet analysis method offers a robust solution for correcting defective pixels in FPIs for CBVCT.
• This approach significantly reduces streak and ring artifacts, enhancing CBVCT image quality.
• The method's multi-resolution and localizability properties ensure reliable performance under varying exposure conditions.