Abstract
X-ray phase contrast imaging offers higher sensitivity compared to conventional X-ray attenuation imaging and can be simply implemented by propagation when using a partially coherent synchrotron beam. We address the phase retrieval in in-line phase nano-CT using multiple propagation distances. We derive a method which extends Paganin's single distance method and compare it to the contrast transfer function (CTF) approach in the case of a homogeneous object. The methods are applied to phase nano-CT data acquired at the voxel size of 30 nm (ID16A, ESRF, Grenoble, France). Our results show a gain in image quality in terms of the signal-to-noise ratio and spatial resolution when using four distances instead of one. The extended Paganin's method followed by an iterative refinement step provides the best reconstructions while the homogeneous CTF method delivers quasi comparable results for our data, even without refinement step.
Highlights
Imaging the three-dimensional (3D) organization of bone structures has been a pioneering application in micro-computerized tomography [1]
Minimum Intensity Projections (MIPs) of the 3D reconstructed volumes for a human cortical bone sample are shown in Figs. 3 and 4, respectively for the homogeneous contrast transfer function (CTF) and the extended Paganin’s method
Phase retrieval which is a non-linear ill-posed inverse problem is a necessary step in the reconstruction of propagation-based synchrotron radiation (SR) X-ray phase nano-CT
Summary
Imaging the three-dimensional (3D) organization of bone structures has been a pioneering application in micro-computerized tomography (micro-CT) [1]. An additional advantage of SR micro-CT is the facility to implement X-ray phase imaging with the high degree of spatial coherence. This technique is attracting more attention with the progresses in SR sources, detectors and computing facilities. Since its sensitivity can be more than three-orders of magnitude higher than attenuation-based imaging, it enables imaging of weakly absorbing samples such as soft tissue and of materials with small changes in attenuation [3,4]. Phase micro-CT has been used in many biomedical areas and has provided valuable images of small animals or biological samples at micrometric scale. It was used to image small animals [5], brain tissue [6] and lung microstructure [7]
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