X-ray diffraction tomography at the Australian National Beamline Facility

Grant, Jason A.; Davis, John R.; Wells, P.N.T.; Morgan, Michael J.

doi:10.1117/12.173548

Cited by 10 publications

(5 citation statements)

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“…The maxima of the coherent cross sections occur at larger angles, thereby increasing the angular resolution. Grant et al (1993Grant et al ( , 1994Grant et al ( , 1995 have developed a microversion of a diffraction CT apparatus (figure 14). They do not use a ring-shaped detector and thus lose in efficiency.…”

Section: Diffraction Ctmentioning

confidence: 99%

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Imaging modalities in x-ray computerized tomography and in selected volume tomography

Carlsson

1999

Phys. Med. Biol.

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This review of different principles used in x-ray computerized tomography (CT) starts with attenuation (transmission) CT. The pros and cons of different geometrical solutions, single-ray, fan-beam and cone-beam, are discussed. Attenuation CT measures the spatial distribution of the linear attenuation coefficient, mu. The contributions of different interaction processes to mu have also been used for CT. Fluorescence CT is based on measurements of the contribution, cZtauZ/rho, from an element Z with concentration cZ, to the linear attenuation coefficient. Diffraction CT measures the differential coherent cross section d sigma (theta)(coh)/d omega, Compton CT the incoherent scatter cross section sigma. The usefulness of these modalities is illustrated. CT methods based on secondary photons have a competitor in selected volume tomography. These two tomography methods are compared. A proposal to perform Compton profile tomography is also discussed, as is the promising method of phase-contrast x-ray CT.

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Section: Diffraction Ctmentioning

confidence: 99%

“…In subsequent work by the same group (Grant et al 1994), they used synchrotron radiation tuned to give essentially monoenergetic radiation in the range 5 to 20 keV and showed that it is possible to map the spatial orientation of crystallites within specimens.…”

Section: Diffraction Ctmentioning

confidence: 99%

Imaging modalities in x-ray computerized tomography and in selected volume tomography

Carlsson

1999

Phys. Med. Biol.

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“…Harding and co-workers first demonstrated that crystallography and medical imaging techniques could be successfully joined to form a powerful new technique, mapping spatial variations in molecular structure throughout an extended, inhomogeneous specimen. 1,2 Several authors have followed suit [3][4][5][6][7][8][9][10][11][12][13] and proposed various methods for coherent-scatter imaging. Many applications have been proposed for public safety purposes, such as the screening of foodstuffs for contaminants or of checked baggage for explosives or drugs.…”

Section: Introductionmentioning

confidence: 99%

“…Harding et al adapted the ''white beam'' x-ray diffraction method to imaging, 3 using 100 kVp polychromatic radiation and an energy-resolving detector ͑high-purity germanium͒ at a fixed angle and performing a raster scan of the specimen. Other groups 8,15 have abandoned diagnostic sources and are developing tomographic systems using high brilliance, monochromatic synchrotron sources. These are not, however, widely accessible.…”

Section: Introductionmentioning

confidence: 99%

Material‐specific analysis using coherent‐scatter imaging

Batchelar

Cunningham

2002

Medical Physics

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Coherent-scatter computed tomography (CSCT) is a novel imaging method we are developing to produce cross-sectional images based on the low-angle (<10 degrees) scatter properties of tissue. At diagnostic energies, this scatter is primarily coherent with properties dependent upon the molecular structure of the scatterer. This facilitates the production of material-specific maps of each component in a conglomerate. Our particular goal is to obtain quantitative maps of bone-mineral content. A diagnostic x-ray source and image intensifier are used to acquire scatter patterns under first-generation CT geometry. An accurate measurement of the scatter patterns is necessary to correctly identify and quantify tissue composition. This requires corrections for exposure fluctuations, temporal lag in the intensifier, and self-attenuation within the specimen. The effect of lag is corrected using an approximate convolution method. Self-attenuation causes a cupping artifact in the CSCT images and is corrected using measurements of the transmitted primary beam. An accurate correction is required for reliable density measurements from material-specific images. The correction is shown to introduce negligible noise to the images and a theoretical expression for CSCT image SNR is confirmed by experiment. With these corrections, the scatter intensity is proportional to the number of scattering centers interrogated and quantitative measurements of each material (in g/cm3) are obtained. Results are demonstrated using both a series of poly(methyl methacrylate) (PMMA) sheets of increasing thickness (2-12 mm) and a series of 5 acrylic rods containing varying amounts of hydroxyapatite (0-0.400 g/cm3), simulating the physiological range of bone-mineral density (BMD) found in trabecular bone. The excellent agreement between known and measured BMD demonstrates the viability of CSCT as a tool for densitometry.

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“…The original approach to image reconstruction in XDT (Harding et al 1985) utilized summation filtered backprojection (FBP). The limitations of FBP reconstruction in this context have been discussed by Grant et al (1993Grant et al ( , 1994. Despite its shortcomings for XDT, summation FBP continues to be the favoured approach for tomographic image reconstruction based on scattered x-ray data.…”

Section: Introductionmentioning

confidence: 99%

Implementation of an analyser crystal method for x-ray diffraction tomography

Kewish¹,

Davis²,

Nikulin³

et al. 2001

J. Phys. D: Appl. Phys.

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In this paper we present an experimental method which is well suited to synchrotron x-ray diffraction tomography. The experimental technique utilizes an analyser crystal placed in the diffracted x-ray beam to selectively detect diffracted photons at the desired scattering angle. This arrangement selects the prominent diffraction feature of a specimen component, allowing the spatial distribution of that component to be specifically and quantitatively imaged. Images of the spatial variation of the differential x-ray scattering cross section (reflectivity) in a cross sectional plane of interest are reconstructed using an iterative algebraic technique and an error functional minimization. Reconstructed images of a well characterized phantom show that material features can be clearly delineated. Images based on the spatial variation of x-ray linear attenuation coefficients and differential coherent scattering cross sections have been reconstructed with approximately 125 µm spatial resolution in the imaging plane.

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X-ray diffraction tomography at the Australian National Beamline Facility

Cited by 10 publications

References 0 publications

Imaging modalities in x-ray computerized tomography and in selected volume tomography

Imaging modalities in x-ray computerized tomography and in selected volume tomography

Material‐specific analysis using coherent‐scatter imaging

Implementation of an analyser crystal method for x-ray diffraction tomography

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