CT number

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a symbol, as a figure or word, expressive of a certain value or a specified quantity determined by count.
atomic number (Z) a number expressive of the number of protons in an atomic nucleus, or the positive charge of the nucleus expressed in terms of the electronic charge.
Avogadro's number (N) (NA) the number of molecules in one mole of a substance: 6.023 × 1023. Called also Avogadro's constant.
CT number the density assigned to a voxel in a CAT scan on an arbitrary scale on which air has a density −1000; water, 0; and compact bone +1000. See also hounsfield unit.
mass number (A) the number of nucleons (protons plus neutrons) in the atom of a nuclide; generally indicated by a superscript preceding the symbol of a chemical element (e.g., 131I), denoting a specific isotope.
oxidation number a number assigned to each atom in a molecule or ion that represents the number of electrons theoretically gained (positive oxidation numbers) or lost (negative numbers) in converting the atom to the elemental form.
Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. © 2003 by Saunders, an imprint of Elsevier, Inc. All rights reserved.

CT num·ber

a normalized value of the calculated x-ray absorption coefficient of a pixel (picture element) in a computed tomogram, expressed in Hounsfield units, where the CT number of air is -1000 and that of water is 0.
Synonym(s): Hounsfield number
Farlex Partner Medical Dictionary © Farlex 2012


Godfrey N., English electronics engineer and Nobel laureate, 1919–.
Hounsfield number - a normalized value of the calculated x-ray absorption coefficient of a pixel in a computed tomogram. Synonym(s): CT number
Hounsfield unit - a normalized index of x-ray attenuation used in CT imaging.
Medical Eponyms © Farlex 2012
References in periodicals archive ?
An enhanced image of the cracks in concrete can be created by subtracting the CT numbers at the same positions in concrete CT images for the same cross section at different stress stages.
Analysis based on CT numbers makes the study of the evolution of mesoscopic damage of rock and concrete possible.
Caption: Figure 14: CT number distribution diagram of the sandstone specimens attacked by sulfuric acid solution (pH = 1) for (a) 0 day, (b) 30 days, (c) 90 days, and (d) 180 days.
The initial damage characteristics of sandstone are the unimodal distribution [19] of CT numbers (Figure 14(a)).
The CT numbers are measured in the Hounsfield Unit (HU), which are essential to differentiate between the different tissues in the body by evaluating their attenuation values [2].
Establishment of the linear relationship between green disc density and its CT number
These observations complied with the results of CT number analysis.
The CT number and CT images of typical sections of CT triaxial tests are obtained through 3D reconstruction to study mesostructure evolutions of gravelly soils under the triaxial compressive condition.
In CT, the CT number is used for assigning thresholds to tissues.
Window level and width selections define the shades of gray (Hounsfield units or CT numbers) to be displayed.
(3) A Norwegian group proposed a solution to this problem using prediction equations based on histograms of CT numbers in the region of interest.
The PET scans are corrected for attenuation with coefficients obtained by scaling the CT numbers to the PET energy level (511 kV).