Experimental optimization of X-ray propagation-based phase contrast imaging geometry.

Area of Science:

• Medical Imaging
• Materials Science
• Physics

Background:

• Propagation-based phase contrast imaging (PB-PCI) using X-ray lab sources offers micrometer-scale imaging for low-absorption materials like soft tissues and plastics.
• PB-PCI performance is often constrained by source flux, coherence, and critical setup geometry, presenting a trade-off between contrast-to-noise ratio (CNR) and fringe contrast.

Purpose of the Study:

• To experimentally investigate and validate theoretical models for optimizing PB-PCI setup geometry.
• To systematically analyze the trade-off between CNR and fringe contrast by varying magnification and source-detector distances.

Main Methods:

• Utilized two high-resolution X-ray imaging systems: a custom Cu X-ray source setup and a commercial W X-ray source system (Zeiss Xradia).
• Measured fringe contrast, CNR, and fringe separation for a low-absorption test sample across 130 combinations of magnification and overall distances.

Main Results:

• Identified that figures-of-merit are highly sensitive to magnification, allowing for an optimal configuration independent of source-detector distance.
• Demonstrated excellent agreement between experimental measurements and theoretical models, particularly when accounting for complex X-ray spectra, especially for broadband sources.

Conclusions:

• Experimental validation confirms the predictive power of theoretical PB-PCI models for optimizing imaging parameters.
• The findings provide practical guidance for enhancing X-ray phase contrast imaging of low-absorption samples by optimizing setup geometry.