SAIP2025

Characterization of a Talbot-Lau X-ray phase contrast system at the Wits Micro-CT Facility

11 Jul 2025, 11:10

20m

Solomon Mahlangu House (University of the Witwatersrand, Johannesburg)

Oral Presentation Track F - Applied Physics Applied Physics

Speaker

Gideon Chinamatira (University of the Witwatersrand)

Description

Grating-based X-ray phase contrast imaging using a Talbot-Lau interferometer has emerged as an effective laboratory-based method to visualize specimens with low absorption contrast [1]. This technique enables simultaneous extraction of absorption, phase contrast, and dark-field images from a single dataset. Characterization studies were undertaken to validate and optimize the performance of the Talint-EDU [2]. phase contrast imaging system installed at the Wits Micro-CT laboratory. Firstly, visibility [3] measurements were conducted through phase-stepping experiments enabling the quantification of fringe contrast across the imaging field. A maximum visibility of 30% was achieved at 40 keV, however, a reduction in visibility was observed towards the grating edges, attributed to minor grating misalignments. Secondly, sensitivity [4] evaluations were performed by varying the sample position relative to the phase grating. The results demonstrated enhanced phase contrast detail when the sample was positioned closer to the phase grating, highlighting the importance of sample-grating proximity in achieving optimal imaging performance. Finally, system stability [2] was assessed through repeated phase-stepping measurements, confirming high reproducibility and consistent imaging performance under identical experimental conditions. Validation experiments were carried out on two biological specimens: a ground beetle and a preserved Myosorex varius foetus. The imaging results successfully illustrated enhanced visibility of delicate skeletal structures and soft tissues via phase and dark-field modalities, surpassing traditional absorption-based imaging capabilities. This study demonstrates the imaging capabilities and identifies the limitations of the Talint-EDU phase contrast imaging system at the Wits X-ray CT laboratory, providing a basis for future applications and system improvements.

References
1. Weitkamp, T., Diaz, A., David, C., Pfeiffer, F., Stampanoni, M., Cloetens, P., & Ziegler, E. (2005). "X-ray phase imaging with a grating interferometer." Optics Express, 13(16), 6296–6304
2. Gutekunst, J., Fettig, R., Schulz, J. & Glinz, J., 2023. Advancing research and education with simple setup Talbot-Lau-Interferometers. In: Proceedings of the 12th Conference on Industrial Computed Tomography (iCT 2023). e-Journal of Nondestructive Testing, 28(3).
3. Pfeiffer, F., Weitkamp, T., Bunk, O., & David, C. (2006). "Phase retrieval and differential phase-contrast imaging with low-brilliance X-ray sources." Nature Physics, 2(4), 258–261.
4. Chen, G. K., Bevins, N., Zambelli, J., Li, K., Qi, Z., & Chen, G. H. (2010). "X-ray phase sensitive imaging methods: Basic physical principles and potential medical applications." Current Medical Imaging Reviews, 6(2), 90–99.