High resolution 3-dimensional tomography with X-rays at Singapore synchrotron light source

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Abstract

Over the past few years, results from the phase contrast imaging and tomography (PCIT) beamline at the Singapore Synchrotron Light Source (SSLS) have shown that high resolution (about 1 μm) 2-dimensional (2D) and 3-dimensional (3D) can be achieved in spite of the large emittance of the Helios 2 storage ring. Using white radiation the photon flux is high enough to perform real time radiology (100 ms per frame) at high lateral resolution as well as high-speed 2D imaging and 3D tomography. Refractive edge enhancement was also observed. PCIT is mostly used for materials and process characterization.

Introduction

X-rays are uniquely suited for microscopy as their short wavelength allows high spatial resolution. Their interaction with matter provides various contrast mechanisms including absorption contrast, phase contrast, and diffraction contrast. The high penetrating power favors nondestructive imaging of large and opaque structures, as is well known from X-ray computed tomography (X-ray CT) for human medical applications [4]. X-ray tomography is applicable over a wide range of size scales encountered in many disciplines. Computer-Assisted Tomography (CAT) is now a common procedure with object sizes up to few meters. In recent years, 2D and 3D imaging capabilities with a lateral resolution of about 1 μm have been developed at the PCIT beamline at SSLS.

Although several groups [5], [6] have already documented a resolution down to 20 nm with X-rays and 3D tomography when imaging cryogenic single cells and down to below 1 nm [7] with transmission electron microscopy (TEM), the useful sample sizes were limited to less than few μm. However, there is a large pool of applications for which 1 μm resolution tomography is optimal when sample sizes approach 1–2 mm. In this paper, we concentrate on selected applications where 1 μm resolution has been applied. Additionally, a new project at SSLS will be discussed for reaching a resolution down to 50 nm.

Section snippets

Experimental procedure setup and plans

The schematic diagram of the PCIT beamline is presented in Fig. 1. It features a fast valve, ion pumps, a rectangular wall through tube, a γ-shutter and a Be window at the end. At present, it offers a white beam of hard X-rays with a cross section of 20 × 8 mm2 (horizontal × vertical) and maximum flux at a photon energy of 8.8 keV (1.41 Å), within an energy range of about 4–15 keV. The system is designed to produce a beam of about 1 × 1 mm2 at the sample with the use of variable slits. The X-ray beam is

Contrast formation

Although the substantial partial coherence of the X-ray beams from third generation synchrotrons has played an important role in the development of new approaches to imaging [10], [11], [12], [13], [14], [15] and radiology, it is not necessary to achieve useful imaging as demonstrated in work on larger emittance sources such as [1], [2], [3]. When feature sizes of interest are small, mostly refractive edge enhancement helps to improve image quality even with limited spatial and temporal

Results and conclusions

In one of the first demonstrations of the X-ray microtomography at SSLS we used a wooden toothpick. A straight section of the toothpick was selected for the CAT scan. For the X-ray microtomography, multiple two-dimensional projections (approximately ∼1 × 1 mm2 each) were collected at different rotational positions of the sample around the vertical axis. The sample was rotated by 0.18° between each projection. Typically up to 1,000 projections over 180° were collected during a 2 h scan. The X-ray

Acknowledgments

Work partly performed at SSLS under NUS Core Support C-380-003-003-001, A∗STAR/MOE RP 3979908M and A∗STAR 0121050038 grants.

References (17)

  • A. Yeo et al.

    J. Membrane Sci.

    (2005)
  • M.A. Le Gros et al.

    Curr. Opin. Struc. Biol.

    (2005)
  • U. Ziese et al.

    J. Struct. Biol.

    (2002)
  • Y. Hwu et al.

    Using photoelectron emission microscopy with hard X-rays

    Surf. Sci.

    (2001)
  • W.L. Tsai et al.

    Biophys. J.

    (2004)
  • W.L. Tsai, P.C. Hsu, Y. Hwu, J.H. Je, P. Yang, H.O. Moser, A. Groso, G. Margaritondo, Edge-enhanced radiology with...
  • E. Seeram

    Computed Tomography

    (2001)
  • D. Weiss et al.

    Ultramicroscopy

    (2000)
There are more references available in the full text version of this article.

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