A new family of rare earth-rhodium-tin intermetallic compounds, with the representative formula (RE)Rh~Sn~, has been synthesized in single crystal form. The compounds containing the heavier rare earths are superconducting and those with the lighter rare earths are generally magnetic. The compound ErRh Sn 36 exhibits reentrant superconductivity with T~= 0.97 K and Tm = 0.57 K as determined from ac magnetic susceptibility measurements. The synthesis and X-ray characterization of the series are described and the results of electrical resistivity, upper critical magnetic field, magnetic susceptibility, specific heat and neutron scattering measurements on the Er compound are given.

Analyzer-based imaging is a powerful phase-sensitive technique that generates improved contrast compared to standard absorption radiography. Combining numerically two images taken on either side at ±1/2 of the full width at half-maximum (FWHM) of the rocking curve provides images of “pure refraction” and of “apparent absorption.” In this study, a similar approach is made by combining symmetrical images with respect to the peak of the analyzer rocking curve but at general positions, ±α⋅FWHM. These two approaches do not consider the ultrasmall angle scattering produced by the object independently, which can lead to inconsistent results. An accurate way to separately retrieve the quantitative information intrinsic to the object is proposed. It is based on a statistical analysis of the local rocking curve, and allows one to overcome the problems encountered using the previous approaches.

Diffraction enhanced imaging (DEI) is a new, synchrotron-based, x-ray radiography method that uses monochromatic, fan-shaped beams, with an analyser crystal positioned between the subject and the detector. The analyser allows the detection of only those x-rays transmitted by the subject that fall into the acceptance angle (central part of the rocking curve) of the monochromator/analyser system. As shown by Chapman et al, in addition to the x-ray attenuation, the method provides information on the out-of-plane angular deviation of x-rays. New images result in which the image contrast depends on the x-ray index of refraction and on the yield of small-angle scattering, respectively. We implemented DEI in the tomography mode at the National Synchrotron Light Source using 22 keV x-rays, and imaged a cylindrical acrylic phantom that included oil-filled, slanted channels. The resulting 'refraction CT image' shows the pure image of the out-of-plane gradient of the x-ray index of refraction. No image artefacts were present, indicating that the CT projection data were a consistent set. The 'refraction CT image' signal is linear with the gradient of the refractive index, and its value is equal to that expected. The method, at the energy used or higher, has the potential for use in clinical radiography and in industry.

The medical imaging and therapeutic technologies that are based on the use of radiation are reviewed briefly, with special emphasis on the recent developments of synchrotron radiation (SR) methods. New results have been achieved in all of these areas since the last comprehensive reviews were written in this field. This topical review is intended to make the latest possible results and complete set of references available. The different contrast mechanisms in imaging by x-rays are described. The applications range from whole-body imaging to studies of atomic and molecular structures. The SR imaging applications include coronary angiography, bronchography, mammography, computed tomography, x-ray microscopy and imaging by scattering. The therapy applications include photon activation therapy and microbeam radiation therapy.

Small-angle x-ray scattering (SAXS) patterns are recorded from thin breast tissue samples containing healthy and cancerous regions. The SAXS patterns are compared with histo-pathological observations. The information available from SAXS is reviewed, and a model for scattering from collagen is presented. Scattering patterns of collagen at regions far from the tumours are essentially different from those at tumours. The axial period of collagen fibrils is 65.0 +/- 0.1 nm in healthy regions, and 0.3 nm larger in cancer-invaded regions. The average intensity of scattering from cancerous regions is an order of magnitude higher than the intensity from healthy regions. This is interpreted to arise from an increase of the specific surface area of the scatterers, which is due to a disruption of the molecular and supra-molecular structures in cancerous regions and invasion of new types of cells. The differences of the SAXS patterns are large and distinctive enough to suggest that these phenomena may be utilized in mammography.

Seven breast cancer specimens were examined with diffraction-enhanced imaging at 18 keV with a silicon crystal with use of the silicon 333 reflection in Bragg mode. Images were compared with digital radiographs of the specimen, and regions of increased detail were identified. Six of the seven cases (86%) showed enhanced visibility of surface spiculation that correlated with histopathologic information, including extension of tumor into surrounding tissue.

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