Hounsfield unit

Hounsfield unit
(HU)
   a unit used in medical imaging (CT or MRI scanning) to describe the amount of x-ray attenuation of each "voxel" (volume element) in the three-dimensional image. The voxels are normally represented as 12-bit binary numbers, and therefore have 212 = 4096 possible values. These values are arranged on a scale from -1024 HU to +3071 HU, calibrated so that -1024 HU is the attentuation produced by air and 0 HU is the attenuation produced by water. Tissue and bone then produce attenuations in the positive range. The reading in Hounsfield units is also called the CT number. The unit is named for the British engineer Godfrey Hounsfield, who demonstrated the first CT scanner in 1972. For this invention he received the Nobel Prize in medicine in 1979.

Dictionary of units of measurement. 2015.

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  • Hounsfield unit — the numerical unit assigned electronically to each pixel in a computerized tomography (CT) image, according to its X ray density. The fixed points on the scale are arbitrarily assigned as 1000 for air and 0 for water. The CT image is viewed in a… …   The new mediacal dictionary

  • Hounsfield Unit — Der lineare Absorptionskoeffizient μ beschreibt, wie stark monochromatische Röntgenstrahlung beim Durchdringen von Materie entlang des durchstrahlten Wegs abgeschwächt wird. Die Medizin interessiert sich im Rahmen der Computertomografie besonders …   Deutsch Wikipedia

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  • Hounsfield scale — The Hounsfield scale is a quantitative scale for describing radiodensity. DefinitionThe Hounsfield unit (HU) scale is a linear transformation of the original linear attenuation coefficient measurement in one in which the radiodensity of distilled …   Wikipedia

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  • Hounsfield — Godfrey N., British electronics engineer, *1919. Developed first practical computed tomography device, the EMI scanner; received the Nobel prize in Medicine in 1979 jointly with physicist A. M. Cormack. See H. unit, H. number …   Medical dictionary

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