Previously, we designed a new quantitative phase-contrast setup for the microtomography experiments at the hereon beamlines P05 and P07 at PETRA III, DESY. This setup is based on Talbot array illuminators (TAI) as high visibility wavefront markers and can reach a spatial resolution level comparable to propagation-based imaging. In this work, we focus on the progress of bringing this setup into user operation. We collaborated with INI-Research to investigate the vascular system of mouse lymph nodes, exploiting the spatial resolution capabilities and using the quantitative aspect of the data to compare different sample preparation methods. We could successfully visualize and trace the blood supply of the lymph nodes, even with fine capillaries, showing the stability and performance of the setup in user application.
The Helmholtz-Zentrum Hereon, Germany, is operating the user experiments for microtomography at the beamlines P05 and P07 using synchrotron radiation produced in the storage ring PETRA III at DESY, Hamburg, Germany. Attenuation-contrast and phase-contrast techniques were established to provide an imaging tool for applications in biology, medical science and materials science. Within the recent years we built an imaging pipeline to optimize the deliverd radiation dose onto the sample with respect to the applied imaging technique. This became possible by the modernisation of the experiment control and the integration of different imaging detectors. In combination with an new concept for a high-speed X-ray shutter the applied radiation dose can be adjusted from high, for optimization of the statistic within the tomogram, to low, for avoiding any radiation based artefact. Within this talk the recent hardware and software developments integrated to the microtomography imaging system at the beamlinew P05/PETRA III and P07/PETRA III will be presented. Furthermore, the optimization of dose will be demonstrated on selected samples.
Phase-contrast imaging is one of the standard X-ray imaging methods at synchrotron beamlines and has already proven to be beneficial for soft-tissue visualization. However, most implementations use single-distance inline phase-contrast techniques, and are thus not able to provide quantitative information. To access these, grating-based imaging (GBI) setups or, rather recently, speckle-based imaging (SBI) methods can be used. We built a new grating-based setup at the beamline P05 operated by HZG at the storage ring PETRA III / DESY. This new setup overcomes the previously reported limitations in spatial resolution compared to inline phase-contrast imaging. Furthermore, it allows for accurate quantitative phase contrast micro computed tomography of biological soft tissue. We replaced the typically used sandpaper by a 2D phase-grating as a wavefront marker, which increased the visibility and allowed for using fewer phase steps. Combined with an existing SBI phase-retrieval algorithm, the so-called Unified Modulated Pattern Analysis (UMPA) and an optimized scan protocol, we reached a resolution below 4 microns in scan times less than two hours. We investigated stained and unstained tissue samples, to quantify the staining process of different tissue types and were able to observe an increase in electron density, dependent on the stain and tissue type. By this, we could show the successful operation of our setup to quantitatively investigate samples on a micro meter scale at the beamline P05.