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Attenuation. In physics, attenuation (in some contexts, extinction) is the gradual loss of flux intensity through a medium. For instance, dark glasses attenuate sunlight, lead attenuates X-rays, and water and air attenuate both light and sound at variable attenuation rates. Hearing protectors help reduce acoustic flux from flowing into the ears ...
Kinetic image or DVA (digital variance angiography) of a patient's leg, obtained from previously acquired fluoroscopic angiography data. Movement of a bolus of contrast agent allows visualization of the blood vessels. Kinetic imaging is an imaging technology developed by Szabolcs Osváth and Krisztián Szigeti in the Department of Biophysics ...
The adjacent normal lung tissue with lower attenuation appears as darker areas. Ground-glass opacity (GGO) is a finding seen on chest x-ray (radiograph) or computed tomography (CT) imaging of the lungs. It is typically defined as an area of hazy opacification (x-ray) or increased attenuation (CT) due to air displacement by fluid, airway ...
Mass attenuation coefficients of selected elements for X-ray photons with energies up to 250 keV. The mass attenuation coefficient, or mass narrow beam attenuation coefficient of a material is the attenuation coefficient normalized by the density of the material; that is, the attenuation per unit mass (rather than per unit of distance).
Dual-energy X-ray absorptiometry. Dual-energy X-ray absorptiometry (DXA, or DEXA[1]) is a means of measuring bone mineral density (BMD) using spectral imaging. Two X-ray beams, with different energy levels, are aimed at the patient's bones. When soft tissue absorption is subtracted out, the bone mineral density (BMD) can be determined from the ...
The linear attenuation coefficient, attenuation coefficient, or narrow-beam attenuation coefficient characterizes how easily a volume of material can be penetrated by a beam of light, sound, particles, or other energy or matter. [1] A coefficient value that is large represents a beam becoming 'attenuated' as it passes through a given medium ...
Spectral imaging (radiography) Spectral imaging is an umbrella term for energy-resolved X-ray imaging in medicine. [1] The technique makes use of the energy dependence of X-ray attenuation to either increase the contrast-to-noise ratio, or to provide quantitative image data and reduce image artefacts by so-called material decomposition.
A material's half-value layer (HVL), or half-value thickness, is the thickness of the material at which the intensity of radiation entering it is reduced by one half. [1] HVL can also be expressed in terms of air kerma rate (AKR), rather than intensity: the half-value layer is the thickness of specified material that, "attenuates the beam of radiation to an extent such that the AKR is reduced ...