Model-Based Iterative Reconstruction for Propagation-Based Phase-Contrast X-Ray CT including Models for the Source...

Area of Science:

• Medical imaging
• X-ray computed tomography
• Phase-contrast imaging

Background:

• Propagation-based phase-contrast X-ray computed tomography (PBPCT) offers high-resolution biological sample visualization with lower dose than conventional methods.
• Transitioning PBPCT from synchrotrons to laboratory X-ray sources presents challenges like limited spatial coherence and flux, impacting resolution and noise.
• Existing iterative reconstruction algorithms require enhancement to address laboratory source limitations.

Purpose of the Study:

• To extend iterative reconstruction algorithms for PBPCT to incorporate models of reduced spatial coherence and detector signal spreading.
• To implement a noise model accounting for full covariance statistics in the image formation process.
• To adapt interference effect modeling to align with the single-material phase-retrieval algorithm formalism.

Main Methods:

• Developed an iterative reconstruction algorithm incorporating physical forward models for source coherence and detector response.
• Integrated a noise model capturing full covariance statistics of the image formation process.
• Modified interference modeling to match the single-material phase-retrieval algorithm.

Main Results:

• Simulations and experiments at a laboratory inverse Compton source demonstrated significant resolution improvements compared to analytical methods.
• Modeling source and detector characteristics within the forward model enhanced resolution at matched noise levels.
• Covariance statistics modeling effectively reduced overshoots at sample edges.

Conclusions:

• The enhanced iterative reconstruction algorithm significantly improves resolution and reduces artifacts in laboratory-based PBPCT.
• Accurate modeling of source and detector properties is crucial for high-quality phase-contrast CT imaging.
• This approach offers a pathway to overcome limitations of laboratory X-ray sources for advanced imaging applications.