Berlin 2024 – scientific programme

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BP: Fachverband Biologische Physik

BP 17: Bioimaging

BP 17.1: Talk

Wednesday, March 20, 2024, 09:30–09:45, H 2032

X-ray tomography techniques for predicting medical implants performance — •Tatiana Akhmetshina, Robin E. Schäublin, Andrea M. Rich, and Jörg F. Löffler — Laboratory of Metal Physics and Technology, Department of Materials, ETH Zurich, Switzerland

Mg-based temporary implants that can be resorbed after fracture healing are beneficial for patients and necessary in certain clinical applications. However, since Mg reacts with body fluids and dissolves, we need reliable data to predict the implants performance in vivo. X-ray tomography techniques can provide valuable insights into the degradation behavior, but they also show limits in materials characterization. While absorption contrast works very well for some materials, in Mg-based alloys we often have features (second-phase particles) that cannot be resolved due to their low contrast. Additionally, the resolution required to characterize the material and understand the microstructure-property relationships is below 100 nm. In this study, we compare two distinct X-ray tomography techniques (Zernike and ptychography) to examine their advantages and disadvantages and present a case study focused on Mg-based alloys (WE43 and Mg-Ca: X0). Our results show that ptychographic tomography resolves features of less than 10% difference in their densities, such as a Mg2Ca phase in a Mg-Ca alloy, which is not possible with the Zernike. The 3D resolution reached is 23 nm, which allowed us to distinguish fine microstructural details. This illustrates the suitability of ptychographic X-ray computed tomography for the characterization of Mg alloys.

Keywords: medical implants; tomography; corrosion