Hounsfield unit

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1. a single thing; one segment of a whole that is made up of identical or similar segments.
2. a specifically defined amount of anything subject to measurement, as of activity, dimension, velocity, volume, or the like.
3. a distinct part of a hospital, usually having a specific physical location and serving a defined function; see under names of specific units.
Ångström unit angstrom.
atomic mass unit (u) (amu) the unit of mass equal to ¹⁄₁₂ the mass of the nuclide of carbon 12. Called also dalton.
autonomous nursing unit a nursing unit under a decentralized administration system in which the staff is responsible for all aspects of unit functioning.
British thermal unit (BTU) a unit of heat formerly widely used, being the amount necessary to raise the temperature of 1 pound of water from 39° to 40°F., equal to approximately 252 calories.
CH50 unit the amount of complement that will lyse 50 per cent of a standard preparation of sheep red blood cells coated with antisheep erythrocyte antibody.
continuing education unit (CEU) a unit of credit for educational offerings given to professional persons, determined by a professional organization according to a mathematical formula after a thorough review of the program of study, the qualifications of the instructors, and the program objectives.
critical care unit intensive care unit.
electrostatic u's (esu) that system of units that is based on the fundamental definition of a unit charge as one that will repel a similar charge with a force of 1 dyne when the two charges are 1 cm apart in a vacuum.
environmental control unit a computerized system that allows the handicapped individual to operate several different appliances using a keyboard or other input device.
heat unit the amount of heat energy that is produced by one kVp (kilovolt peak) and one mA (milliampere) for one second with single phase, full wave rectified radiographic equipment.
Hounsfield unit an arbitrary unit of x-ray attenuation used for CT scans. Each voxel is assigned a value on a scale in which air has a value of −1000; water, 0; and compact bone, +1000.
intensive care unit see intensive care unit.
International unit (IU)
1. a unit of enzyme activity equal to the amount of enzyme that catalyzes the conversion of one micromole of substrate or coenzyme per minute under specified conditions (temperature, pH, and substrate concentration) of the assay method. Abbreviated U.
2. any of several arbitrary units that have been adopted by international bodies to express the quantities of certain vitamins (A, C, D, and thiamine hydrochloride), hormones (androgen, chorionic gonadotropin, estradiol benzoate, estrone, insulin, progesterone, and prolactin), and drugs (digitalis and penicillin).
Kienböck's unit a unit of x-ray exposure equal to 0.1 erythema dose; symbol X.
motor unit the unit of motor activity formed by a motor nerve cell and its many innervated muscle fibers.
postanesthesia care unit (PACU) a specialty unit in a hospital for giving postanesthesia care (care of patients recovering from anesthesia and intravenous sedation); formerly called recovery room.
radiologic u's units used to measure radiation, including roentgens, rads, rems, and curies.
u's of service (UOS)
1. the number of procedures done by a department.
2. individuals or groups of individuals who are the recipients of nursing care.
short procedures unit (short term care unit) a nursing unit where patients are briefly cared for following a medical or surgical procedure and are then discharged without spending the night.
SI unit any unit of the International System of units (the metric system); see also si units.
step-down unit a nursing unit designated to provide care for patients who are stable enough to be discharged from the intensive care unit but are not yet ready to be cared for on a medical-surgical unit.
Svedberg unit (S) a unit equal to 10−13 second used for expressing sedimentation coefficients of macromolecules.
Svedberg flotation unit (Sf) a unit equal to 10−13 second used for expressing negative sedimentation coefficients of macromolecules that float rather than sink in a centrifuge, e.g., lipoproteins.
terminal respiratory unit the functional unit of the lung, including a respiratory bronchiole, alveolar ducts and sacs, and alveoli; called also primary lobule of lung and primary respiratory lobule.
USP unit one used in the United States Pharmacopeia for expressing potency of drugs and other preparations.
Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. © 2003 by Saunders, an imprint of Elsevier, Inc. All rights reserved.

Houns·field u·nit

a normalized index of x-ray attenuation based on a scale of -1000 (air) to +1000 (bone), with water being 0; used in CT imaging.
Farlex Partner Medical Dictionary © Farlex 2012

Houns·field u·nit

(HU) (hownz'fēld yūnit)
Normalized index of x-ray attenuation based on a scale of -1000 (air) to +1000 (bone), with water being 0; used in CT imaging.
Medical Dictionary for the Health Professions and Nursing © 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 ?
Investigation of the relationship between linear attenuation coefficients and CT Hounsfield units using radionuclides for SPECT.
TABLE 2: Diagnostic indices of a cut-off value of parenchymal Hounsfield unit in nonenhanced CT for detecting diffuse thyroid disease in 209 patients.
Metin, "Does the Hounsfield unit value determined by computed tomography predict the outcome of percutaneous nephrolithotomy?" Journal of Endourology, vol.
Scanner data are presented in Hounsfield units, which are the scaled attenuation coefficients relative to the attenuation of water.
[4] CT allows a definitive diagnosis when it demonstrates a homogeneous fat attenuating mass (-50 to -150 Hounsfield units or HU) forming obtuse angles with the chest wall and displaces adjacent pulmonary parenchyma and vessels.
Noncontrast head CT demonstrated bifrontal and convexial (intrahemispheric) intracranial air, also known as pneumocephalus (-1000 Hounsfield units), on the bone window.
A contrast enhanced computed tomography (CT) of abdomen according to the adrenal protocol showed a right-sided homogenously dense (density of 9.5 Hounsfield Units {HU}) adrenal lesion measuring 1.6 x 1.3 x 0.8 cm with an absolute washout of 67% confirming benign nature of the lipid rich adrenal adenoma (Figure 1).
While a positive density is observed in normal parotid tissue, a well-demarcated hypodense density (-50 to -150 Hounsfield units) can be identified in lipomatous tissue in contrast-enhanced images [1,10].
The bone height was measured using the CT Scans along with the bone density in terms of Hounsfield units and an implant was chosen accordingly.
The cerebellum appeared to be ventrally compressed by a homogeneous, triangular, fluid-attenuating region (0-10 Hounsfield units).