High resolution 3-dimensional tomography with X-rays at Singapore synchrotron light source
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)
- et al.
J. Membrane Sci.
(2005) - et al.
Curr. Opin. Struc. Biol.
(2005) - et al.
J. Struct. Biol.
(2002) - et al.
Using photoelectron emission microscopy with hard X-rays
Surf. Sci.
(2001) - 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...
Computed Tomography
(2001)- et al.
Ultramicroscopy
(2000)
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A synchrotron X-ray imaging strategy to map large animal brains
2020, Chinese Journal of PhysicsCitation Excerpt :These facilities operate microtomography and/or nanotomography systems suitable for the task. Specifically, we used the 6C [39] and 7C beamlines [40] of PLS-II, the 1A and 1B beamlines of TLS [41], the Brain Imaging beamline of TPS, the 29XU beamline of SPring-8 [42] and the PCIT (Phase Contrast Imaging and Tomography) beamline [43] of SSLS. Among these, the PLS-II 7C, TLS 1B and SPring-8 29XU beamlines are nanoresolution microscopy facilities.
ANKAphase: Software for single-distance phase retrieval from inline X-ray phase-contrast radiographs
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