Criteria for selecting the Paganin-filter reconstruction parameter in X-ray phase-contrast tomography

Area of Science:

• Physics
• Materials Science
• Imaging Science

Background:

• The Paganin filter is crucial for phase-contrast X-ray computed tomography (CT) using synchrotron light.
• It corrects phase effects and reduces noise but relies on assumptions about sample properties (constant β/δ ratio).
• Empirical parameter selection often leads to suboptimal image quality in real-world samples.

Purpose of the Study:

• To develop a quantitative, noise-aware criterion for optimizing the Paganin filter parameter.
• To eliminate the need for subjective, empirical tuning of the filter parameter.
• To improve image quality in phase-contrast CT by automating parameter selection.

Main Methods:

• Method 1: Analyzes the noise power spectrum using a Fourier Ring Correlation (FRC) framework to balance resolution enhancement and noise amplification.
• Method 2: Examines reconstructed image variations with changing filter parameters to find an inflection point balancing noise suppression and smoothing.
• Both methods provide automated parameter selection for Paganin-filtered phase-contrast tomography data.

Main Results:

• Developed two distinct, quantitative methods for automated Paganin filter parameter selection.
• Method 1 establishes a theoretical lower bound on FRC for noise suppression and resolution.
• Method 2 identifies an inflection point for optimal noise-noise/smoothing balance.

Conclusions:

• Introduced objective criteria for selecting the Paganin filter parameter, overcoming limitations of empirical tuning.
• The proposed methods offer automated, near-optimal parameter selection for phase-contrast CT.
• This work enhances the reliability and efficiency of image analysis in phase-contrast tomography.