Search results
Results from the WOW.Com Content Network
Dual-energy X-ray absorptiometry (DXA, or DEXA [1]) is a means of measuring bone mineral density (BMD) with spectral imaging. Two X-ray beams, with different energy levels, are aimed at the patient's bones. When soft tissue absorption is subtracted, the bone mineral density (BMD) can be determined from the absorption of each beam by bone. Dual ...
To reduce soft-tissue errors in DXA, DXL technology was developed in the late 1990s by a team of Swedish researchers led by Prof. Ragnar Kullenberg. With DXL technology, the region of interest is scanned using low and high energy x-rays as with a DXA scan. The improvement to DXA with DXL is that, for each pixel scanned by DXA, the exact ...
The more attenuation degree is, the more absorbed by bone minerals, the more bone mineral content and the higher bone mineral density are. This method is called gamma-ray absorption method, which is also called single-photon absorption method. This method is the most convenient for measuring radius and ulna, and the object of observation is left.
Small-angle X-ray scattering (SAXS) is a small-angle scattering technique by which nanoscale density differences in a sample can be quantified. This means that it can determine nanoparticle size distributions, resolve the size and shape of (monodisperse) macromolecules, determine pore sizes and characteristic distances of partially ordered materials. [1]
X-ray absorption spectroscopy (XAS) is a widely used technique for determining the local geometric and/or electronic structure of matter. [1] The experiment is usually performed at synchrotron radiation facilities, which provide intense and tunable X-ray beams. Samples can be in the gas phase, solutions, or solids. [2]
This is done by regressing a line to the region before and after the absorption edge, subtracting the pre-edge line from the entire data set and dividing by the absorption step height, which is determined by the difference between the pre-edge and post-edge lines at the value of E0 (on the absorption edge).
The fixed scattering angle geometry makes EDXRD especially suitable for in situ studies in special environments (e.g. under very low or high temperatures and pressures). When the EDXRD method is used, only one entrance and one exit window are needed. The fixed scattering angle also allows for measurement of the diffraction vector directly.
Often, instead of X-ray emission, the excess energy is transferred to a third electron from a further outer shell, prompting its ejection. This ejected species is called an Auger electron, and the method for its analysis is known as Auger electron spectroscopy (AES). [3]