Tables of X-Ray Mass Attenuation Coefficients and Mass Energy-Absorption Coefficients
ABSTRACT This page provided by the National Institute of Standards and Technology (NIST) presents tables and graphs of the photon mass attenuation coefficient and the mass energy-absorption coefficient for all of the elements Z = 1 to 92, and for 48 compounds and mixtures of radiological interest. The tables cover energies of the photon (x-ray, gamma ray, bremsstrahlung) from 1 keV to 20 MeV. The compilation is intended to be used as reference data in radiation shielding and dosimetry computations.
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ABSTRACT: ZnO doped with Bi2O3 and Sb2O3 (ZBS), is the basic system for ceramic varistors. Phase formation during sintering of ZBS was measured in situ, using 1mm thick samples and synchrotron X-rays. Sintering shrinkage was measured in different atmospheres by an optical method. Thermodynamic calculations were performed to explain phase formation, composition, stability of additive oxides and influence of the oxygen fugacity on sintering. Sb2O4, pyrochlore, trirutile and spinel were formed at temperatures of 500–800°C. The oxidation of antimony was controlled by the oxygen partial pressure and affected both, phase formation and sintering kinetics, in the ZBS system.Ceramics International 01/2009; 35:3313-3320. · 1.79 Impact Factor
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ABSTRACT: Accurate knowledge of the morphology of the human brain is required for minimally or non-invasive surgical interventions. On the (sub-)cellular level, brain tissue is generally characterized using optical microscopy, which allows extracting morphological features with a wide spectrum of staining procedures. The preparation of the histological slices, however, often leads to artifacts resulting in imperfect morphological data. In addition, the generation of 3D data is time-consuming. Therefore, we propose synchrotron radiation-based micro computed tomography (SRmicroCT) avoiding preparation artifacts and giving rise to the 3D morphology of features such as gray and white matter on the micrometer level. One can differentiate between white and gray matter without any staining procedure because of different X-ray absorption values. At the photon energy of 10keV, the white matter exhibits the absorption of 5.08 cm(-1), whereby the value for the gray matter corresponds to 5.25 cm(-1). The tomography data allow quantifying the local strains in the histological images using registration algorithms. The deformation of histological slices compared to the SRmicroCT in a 2D-2D registration leads to values of up to 6.3%. Mean deformation values for the Nissl-stained slices are determined to about 1%, whereas the myelin-stained slices yield slightly higher values than 2%.Journal of Neuroscience Methods 06/2008; 170(1):149-55. · 2.11 Impact Factor
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ABSTRACT: There has been increasing interest in the use of a nanoparticle-based media as a contrast-enhancement agent in medical imaging, particularly with gold Nanoparticles in radiography. Particularly attractive, is the prospect of modifying the surface of these materials with monoclonal antibodies to preferentially bind the nanoparticles to tumour sites. These materials differ from conventional molecular agents in their ability to be modified with cell specificity, or tailored for size and shape for maximum uptake. We investigated the consideration that quantum confinement electronic effects in nanometre-sized metals might have an effect on the integrated photon attenuation of gold atoms; in the same manner as these materials affect X-ray absorption and scattering as seen in X-ray absorption spectroscopy. This experiment has been designed to identify any effect on contrast enhancement that might result from employing gold nanoparticles with a variety of sizes. Spherical particles and nanorods were synthesised for this application. Image contrast enhancement was quantified by contrast-to-noise ratio in computed radiography. Results are consistent with existing measurements of gold nanoparticle contrast enhancement in radiography. No significant variation in attenuation depending on particle size was observed. Findings indicate that nanoparticle-based contrast agents in the size range 4-30 nm-can be synthesised for maximum stability or cell specificity (directed cellular uptake) without consideration of effect of size on contrast enhancement.Australasian physical & engineering sciences in medicine / supported by the Australasian College of Physical Scientists in Medicine and the Australasian Association of Physical Sciences in Medicine 04/2011; 34(2):243-9. · 0.89 Impact Factor