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Proceedings Paper

Multilayer coated gratings for phase-contrast computed tomography (CT)
Author(s): Zsolt Marton; Harish B. Bhandari; Harold H. Wen; Vivek V. Nagarkar
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Paper Abstract

By using the principle of grating interferometry, X-ray phase contrast imaging can now be performed with incoherent radiation from standard X-ray tube. This approach is in stark contrast with imaging methods using coherent synchrotron X-ray sources or micro-focus sources to improve contrast. The gratings interferometer imaging technique is capable of measuring the phase shift of hard X-rays travelling through a sample, which greatly enhances the contrast of low absorbing specimen compared to conventional amplitude contrast images. The key components in this approach are the gratings which consists of alternating layers of high and low Z (atomic number) materials fabricated with high aspect ratios. Here we report on a novel method of fabricating the grating structures using the technique of electron-beam (ebeam) thin film deposition. Alternating layers of silicon (Z=14) and tungsten (Z=74) were deposited, each measuring 100 nm each, on a specially designed echelle substrate, which resulted in an aspect ratio of ~100:1. Fabrication parameters related to the thin film deposition such as geometry, directionality, film adhesion, stress and the resulting scanning electron micrographs will be discussed in detail. Using e-beam method large-area gratings with precise multilayer coating thicknesses can be fabricated economically circumventing the expensive lithography steps.

Paper Details

Date Published: 19 March 2014
PDF: 6 pages
Proc. SPIE 9033, Medical Imaging 2014: Physics of Medical Imaging, 90334Z (19 March 2014); doi: 10.1117/12.2043967
Show Author Affiliations
Zsolt Marton, Radiation Monitoring Devices, Inc. (United States)
Harish B. Bhandari, Radiation Monitoring Devices, Inc. (United States)
Harold H. Wen, National Heart, Lung, and Blood Institute (United States)
Vivek V. Nagarkar, Radiation Monitoring Devices, Inc. (United States)


Published in SPIE Proceedings Vol. 9033:
Medical Imaging 2014: Physics of Medical Imaging
Bruce R. Whiting; Christoph Hoeschen, Editor(s)

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