Impact of a single distance phase retrieval algorithm on spatial resolution in X-ray inline phase sensitive imaging.

Area of Science:

• Medical Imaging
• X-ray Imaging
• Image Processing

Background:

• Phase-sensitive X-ray imaging techniques are emerging for enhanced contrast and resolution.
• Phase retrieval methods aim to reconstruct phase information from X-ray measurements.
• Comparing spatial resolution between direct phase-sensitive imaging and retrieved phase images is crucial for clinical applicability.

Purpose of the Study:

• To compare the spatial resolution of phase-sensitive images and phase-retrieved images using a single-projection phase attenuation duality (PAD) method.
• To evaluate the performance of a prototype inline phase-sensitive X-ray imaging system.

Main Methods:

• A phase-sensitive X-ray imaging prototype with a micro-focus source and 50 μm pixel pitch detector was used.
• A phantom with adipose-glandular mimicking material and a PMMA sharp edge was imaged.
• Phase-sensitive images were acquired and processed using the PAD method.
• Modulation Transfer Function (MTF) curves were calculated to assess spatial resolution.

Main Results:

• Phase-sensitive images demonstrated higher spatial resolution across all spatial frequencies compared to PAD-processed phase-retrieved images.
• The PAD method suppressed high-frequency signal components, leading to lower MTF values in retrieved images.
• Cutoff resolution (10% MTF) decreased by 32% (from 15.6 to 10.6 lp/mm) in phase-retrieved images compared to phase-sensitive images.

Conclusions:

• Direct phase-sensitive imaging provides superior spatial resolution over PAD-based phase retrieval for this X-ray prototype.
• The spatial resolution achieved is sufficient for radiographic breast cancer detection.
• Further optimization of phase retrieval algorithms may be needed to preserve high-frequency details.