Christian David

Structured scintillator for hard x-ray grating interferometry

Grating interferometry at conventional x-ray tubes improves the quality of radiographies and tomograms by providing phase and scattering contrast data. The main challenge encountered when applying this technique at high photon energies, as required by many applications to obtain sufficient penetration depth, is to maintain a high fringe visibility. In this letter, we report on a substantial improvement in fringe visibility and according improvements in image quality achieved by replacing the absorbing analyzer grating of the interferometer with a structured scintillator grating. This development represents a significant step toward the implementation of this technique in industrial testing and medical applications.

9th International Conference on X-Ray Microscopy

This volume compiles the contributions to the International Conference on X-Ray Microscopy (XRM2008) held on 20–25 July 2008 in Zurich, Switzerland. The conference was the ninth in a series which started in Gottingen in 1984. Over the years the XRM conference series has served as a forum bringing together all relevant players working on the development of methods, building instrumentation, and applying x-ray microscopy to challenging issues in materials science, condensed matter research, environmental science and biology. XRM2008 was attended by about 300 participants who followed 44 oral presentations and presented 220 posters. Figure 1: Participants of the XRM2008 conference gathered in front of the main building of the ETH-Zurich. The conference showed that x-ray microscopy has become a mature field resting on three pillars. The first are workhorse instruments available even to non-specialist users. These exist at synchrotron sources world-wide as well as in laboratories. They allow the application of established microscopy methods to solve scientific projects in areas as diverse as soil science, the investigation of cometary dust particles, magnetic materials, and the analysis of ancient parchments. Examples of all of these projects can be found in this volume. These instruments have become so well understood that now they are also commercially available. The second pillar is the continued development of methods. Methods like stroboscopic imaging, wet cells or high and low temperature environments add versatility to the experiments. Methods like phase retrieval and ptychographic imaging allow the retrieval of information which hitero was thought to be inaccessible. The third pillar is the extension of such instruments and methods to new photon sources. With x-ray free electron lasers on the horizon the XRM community is working to transfer their know-how to these novel sources which will offer unprecedented brightness and time structure, but which at the same time require unprecedented effort to perform the experiment and to extract meaningful information from the data. Resting on these three pillars, the XRM community seems well prepared to solve the scientific questions of today and to help solve even more challenging scientific questions in the future. Many people contributed to the success of XRM2008, first and foremost were the participants with their excellent contributions and through their lively discussions. Organizing the event was made possible due to many helping hands and brains at the organizing institution, the Paul Scherrer Institut. It is our pleasure to thank all of these people. Financial support was given by the Gold Sponsor, XRADIA, by the European Round Table for Synchrotrons and Free Electron Lasers, the Center for Imaging Science and Technology at Zurich, and by the Swiss National Science Foundation. The conference was kindly hosted by ETH Zurich which provided a perfect setting for this venue. We thank all the participants of XRM2008, everybody who helped in the organization and all financial supporters and are looking forward to hearing about further progress during XRM2010 which will be organized by Argonne National Laboratory in Chicago. C Quitmann, C David, F Nolting, F Pfeiffer and M Stampanoni Proceedings Editors Figure 2 View over Zurich and into the alps from the terrace of the ETHZ main building during the XRM2008 reception. Figure 3 Flag tosser and Alphorn blowers in front of the ETH Zurich main building during the XRM2008 opening reception. Figure 4 Industry exhibition in the entrance hall of the ETHZ main building. Figure 5 Lively discussions amongst the conference participants took place during the two poster sessions. Figure 6 Lecture hall with the participants busily discussing between talks. Figure 7 Past and present winners of the Werner Meyer-Ilse Award are joined by Andrea Meyer-Ilse, the wife of the deceased x-ray microscopy pioneer Werner Meyer-Ilse. From left to right: Weilun Chao (winner 2005), Ann Sakdinawat (winner 2008), Piere Thibault (winner 2008), Andrea Meyer-Ilse and M Feser (winner 2002). Figure 8 Reception in the court of Schloss Rapperswil during the XRM2008 conference excursion. Figure 9 Conference participants walking towards the castle of Rapperswil during the conference excursion. Figure 10 Accompanying persons group gathered in the port of Lucerne.

Design aspects of X-ray grating interferometry

Considerations are made for the design of X-ray grating interferometers in general and, in particular, for the case of a parallel beam with a high degree of spatial coherence. We specifically discuss the properties of different types of gratings and the interdependence of instrument parameters and performance characteristics.

X-ray grating interferometry - Applications in metrology and wave front sensing

X-ray grating interferometry was first developed in context with x-ray phase contrast imaging. Here we focus on applications where 1- and 2-dimensional grating interferometers are used to measure the distortions of x-ray wave fronts with extreme sensitivity. This allows for the in-situ and at wavelength characterization on x-ray optics such as mirrors and refractive lenses. Angular sensitivities down to the 10 nrad range can be obtained. We point out some specific concerns when using the technique in context with metrology. A precise rotational alignment is essential for accurate, absolute measurements of the local wavefront radius of curvature. Moreover, in many cases no flat-field image can be recorded, therefore the gratings need to fulfill very stringent requirements with respect to distortions.

Phase-contrast Enhanced Mammography: A New Diagnostic Tool for Breast Imaging

Phase contrast and scattering-based X-ray imaging can potentially revolutionize the radiological approach to breast imaging by providing additional and complementary information to conventional, absorption-based methods. We investigated native, non-fixed whole breast samples using a grating interferometer with an X-ray tube-based configuration. Our approach simultaneously recorded absorption, differential phase contrast and small-angle scattering signals. The results show that this novel technique - combined with a dedicated image fusion algorithm - has the potential to deliver enhanced breast imaging with complementary information for an improved diagnostic process.

X‐Ray Grating Interferometry for Phase‐Contrast Imaging and Optics Metrology Applications

We report on a hard x‐ray interferometry technique based on diffraction gratings fabricated using microlithography techniques. Compared to other x‐ray phase‐contrast imaging methods, the grating interferometer only has very moderate requirements in terms of coherence. This makes it possible to use the method with standard x‐ray tubes, which opens up a huge range of applications e.g. in medical imaging.