The past decade has witnessed tremendous growth in both interest and available techniques for laboratory X-ray analysis. From the progression of commercially-available micro- and nano-CT scanners to the resolution and sensitivity enhancements of x-ray fluorescence spectrometers, the scientific community is benefiting from a rapid expansion of laboratory-based x-ray techniques.
In our work, we have developed a suite of advanced x-ray instrumentation providing a wide range of enhanced capabilities for specimen characterization. The key enabling technology lies in the X-ray source, which features a microstructured target capable of providing 5-10x higher brightness than conventional sealed-tube x-ray sources and offering power flux densities that rival rotating anode sources. The target array can be custom-designed to incorporate a variety of materials, facilitating fast & easy switching between characteristic emission lines and radiation spectra. This source has been subsequently integrated with state-of-the-art X-ray focusing optics, such as ellipsoidal/paraboloidal capillary lenses and finely-structured Fresnel zone plate imaging objective lenses, and sensitive scintillator-coupled CCD detection systems, opening up new opportunities for advancing laboratory x-ray inspection equipment.
Here, we will describe the system geometries in detail and demonstrate how these new advancements have led us to the development of laboratory micro-XRF, nano-XRM, and XAS instrumentation. We will also briefly introduce the image-centric software workspace, which facilitates novice users to collect data quickly and reliably with minimal training overhead.
High resolution x-ray computed tomography is a powerful non-destructive 3-D imaging method. It can offer superior
resolution on objects that are opaque or low contrast for optical microscopy. Synchrotron based x-ray computed
tomography systems have been available for scientific research, but remain difficult to access for broader users. This
work introduces a lab-based high-resolution x-ray nanotomography system with 50nm resolution in absorption and
Zernike phase contrast modes. Using this system, we have demonstrated high quality 3-D images of polymerized
photonic crystals which have been analyzed for band gap structures. The isotropic volumetric data shows excellent
consistency with other characterization results.
While electron microscopes and AFMs are capable of high resolution imaging to molecular levels, there is an ongoing
problem in integrating these results into the larger scale structure and functions of tissue and organs within a complex
organism. Imaging biological samples with optical microscopy is predominantly done with histology and
immunohistochemistry, which can take up to a several weeks to prepare, are artifact prone and only available as
individual 2D images. At the nano resolution scale, the higher resolution electron microscopy and AFM are used, but
again these require destructive sample preparation and data are in 2D. To bridge this gap, we describe a rapid non
invasive hierarchical bioimaging technique using a novel lab based x-ray computed tomography to characterize complex
biological organism in multiscale- from whole organ (mesoscale) to calcified and soft tissue (microscale), to subcellular
structures, nanomaterials and cellular-scaffold interaction (nanoscale). While MicroCT (micro x-ray computed
tomography) is gaining in popularity for non invasive bones and tissue imaging, contrast and resolution are still vastly
inadequate compared to histology. In this study we will present multiscale results from a novel microCT and nanoCT
(nano x-ray tomography system). The novel MicroCT can image large specimen and tissue sample at histology
resolution of submicron voxel resolution, often without contrast agents, while the nanoCT using x-ray optics similar to
those used in synchrotron radiation facilities, has 20nm voxel resolution, suitable for studying cellular, subcellular
morphology and nanomaterials. Multiscale examples involving both calcified and soft tissue will be illustrated, which
include imaging a rat tibia to the individual channels of osteocyte canaliculli and lacunae and an unstained whole murine
lung to its alveoli. The role of the novel CT will also be discussed as a possible means for rapid virtual histology using a
biopsy of a human regenerated bone sample done without contrast agents and that of other soft tissues with contrast
agents. Comparison between histology, SEM and MRI will be given.
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