Abstract
We demonstrate that phase retrieval and tomographic imaging at the organ level of small animals can be advantageously carried out using the monochromatic radiation emitted by a compact x-ray light source, without further optical elements apart from source and detector. This approach allows to carry out microtomography experiments which - due to the large performance gap with respect to conventional laboratory instruments - so far were usually limited to synchrotron sources. We demonstrate the potential by mapping the functional soft tissue within the guinea pig and marmoset cochlea, including in the latter case an electrical cochlear implant. We show how 3d microanatomical studies without dissection or microscopic imaging can enhance future research on cochlear implants.
Highlights
The three-dimensional (3d) structure of tissues and organs enables their physiological functions, while pathological states are often accompanied by corresponding structural alterations
An important and promising role in this respect is the advent of tabletop synchrotron sources such as the Munich Compact Light Source (MuCLS) which is based on the interaction of accelerated electrons and laser photons[15]
The results demonstrate that the Compact Light Source is well suited for 3d imaging of structurally preserved soft tissue surrounded by bone, with a field of view large enough to cover an entire organ of small animals, using phase contrast based on free propagation in the direct contrast regime (TIE-regime)
Summary
To evaluate the achievable data quality for samples at the small animal organ level, the cochlea of a guinea pig was imaged. Contrast seems enhanced with increasing propagation distance and already in these 2d projections details such as the sub-structure within the bony tissue surrounding the cochlea become visible which are not resolved in the absorption image (see especially the insets in (d–f) and Suppl. A slice through the reconstructed volume in which this effect can be observed is depicted in Fig. 4(a,b) with two different contrast settings in order to optimally represent the bony structure and soft tissue as well as the metallic components. Due to the x-ray emission over the full angular range, the source-to-detector distance is chosen relatively small (z02=317.8 mm) in order to exploit a sufficient fraction of the flux for imaging Note that this leads to a smaller object-to-detector distance compared to the MuCLS setup and a decreased phase-contrast effect.
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