X-ray diffraction tomography with limited projection information

Zheyuan Zhu,Anuj J Kapadia,Alexander Katsevich,Shuo Pang,Joel A Greenberg

doi:10.1038/s41598-017-19089-w

Zheyuan Zhu, Anuj J Kapadia + Show 3 more

Open Access

https://doi.org/10.1038/s41598-017-19089-w

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Journal: Scientific Reports	Publication Date: Jan 11, 2018
Citations: 19	License type: open-access

Affiliation: Duke University, University of Central Florida

Abstract

X-ray diffraction tomography (XDT) records the spatially-resolved X-ray diffraction profile of an extended object. Compared to conventional transmission-based tomography, XDT displays high intrinsic contrast among materials of similar electron density and improves the accuracy in material identification thanks to the molecular structural information carried by diffracted photons. However, due to the weak diffraction signal, a tomographic scan covering the entire object typically requires a synchrotron facility to make the acquisition time more manageable. Imaging applications in medical and industrial settings usually do not require the examination of the entire object. Therefore, a diffraction tomography modality covering only the region of interest (ROI) and subsequent image reconstruction techniques with truncated projections are highly desirable. Here we propose a table-top diffraction tomography system that can resolve the spatially-variant diffraction form factor from internal regions within extended samples. We demonstrate that the interior reconstruction maintains the material contrast while reducing the imaging time by 6 folds. The presented method could accelerate the acquisition of XDT and be applied in portable imaging applications with a reduced radiation dose.

Highlights

X-ray diffraction tomography (XDT) records the spatially-resolved X-ray diffraction profile of an extended object
Synchrotron-based X-ray diffraction tomography (XDT) systems have been used for imaging fibrous collagens and identifying crystalline compounds[1,17,18]
For many X-ray imaging applications, especially in clinical and security fields, X-ray diffraction is ideal for secondary scan[21,22], and scanning the entire object is not necessary; a region-of-interest (ROI) reconstruction displaying high material contrast is desirable

Summary

Results

The reconstruction of the spatially-resolved form factor within the ROI can successfully identify the material distribution based on the point X-ray diffraction profiles. The reconstructed form factor profiles f (q) from the truncated projections are compared to the single point X-ray diffraction profiles (Fig. 2(a)). The material classification of the interior reconstruction was performed using support vector machines (SVMs)[27], which construct optimized hyperplanes to discriminate high-dimensional form factors into five material classes These trained SVMs were first tested to classify the global XDT reconstruction (SI Sec. 3.1). By measuring the complete diffraction profile rather than the transmittance, the XDT reconstruction improves the contrast between soybean oil and methanol, which would be indistinguishable in a traditional CT image (Fig. 2(d), SI Sec. 3). In exterior region, interior XDT scan significantly reduced the administrated dose, showing an average dose reduction of 83% when compared with global scan

Discussion

Findings

Methods