Edge illumination (EI) is an x-ray phase-contrast imaging technique, exploiting sensitivity to x-ray refraction to visualize features, which are often not detected by conventional absorption-based radiography. The method does not require a high degree of spatial coherence and is achromatic and, therefore, can be implemented with both synchrotron radiation and commercial x-ray tubes. Using different retrieval algorithms, information about an object’s attenuation, refraction, and scattering properties can be obtained. In recent years, a theoretical framework has been developed that enables EI computed tomography (CT) and, hence, three-dimensional imaging. This review provides a summary of these advances, covering the development of different image acquisition schemes, retrieval approaches, and applications. These developments constitute an integral part in the transformation of EI CT into a widely spread imaging tool for use in a range of fields.
In this article we discuss three different developments in Edge Illumination (EI) X-ray phase contrast imaging
(XPCi), all ultimately aimed at optimising EI computed tomography (CT) for use in different environments, and
for different applications. For the purpose of reducing scan times, two approaches are presented; the reverse
projection" acquisition scheme which allows a continuous rotation of the sample, and the single image" retrieval
algorithm, which requires only one frame for retrieval of the projected phase map. These are expected to lead
to a substantial reduction of EI CT scan times, a prospect which is likely to promote the translation of EI into
several applications, including clinical. The last development presented is the "modified local" phase retrieval.
This retrieval algorithm is specifically designed to accurately retrieve sample properties (absorption, refraction,
scattering) in cases where high-resolution scans are required in non-ideal environments. Experimental results,
using both synchrotron radiation and laboratory sources, are shown for the various approaches.
The application of x-ray phase contrast computed tomography (PCT) to the field of tissue engineering is dis- cussed. Specific focus is on the edge illumination PCT method, which can be adapted to weakly coherent x-ray sources, permitting PCT imaging in standard (non-synchrotron) laboratory environments. The method was applied to a prominent research topic in tissue engineering, namely the development of effective and reliable decellularization protocols to derive scaffolds from native tissue. Results show that edge illumination PCT provides sufficient image quality to evaluate the microstructural integrity of scaffolds and, thus, to assess the performance of the used decellularization technique. In order to highlight that edge illumination PCT can ultimately comply with demands on a high specimen throughput and low doses of radiation, recently developed strategies for scan time and dose reduction are discussed.