Hounsfield unit


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unit

 [u´nit]
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.

Houns·field u·nit

(hownz'fēld),
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.

Hounsfield unit

[hounz′fēld]
Etymology: Godfrey N. Hounsfield, 20th century English scientist
the numeric information contained in each pixel of a CT image. It is related to the composition and nature of the tissue imaged and is used to represent the density of tissue. Also called CT number, Hounsfield number.

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.

Hounsfield,

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.

hounsfield unit

; HU absorption coefficient unit of radiolucency of a substance; HU is normalized to water, where water = 0 HU, air = -1000 HU and bone = 1000 HU

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.
References in periodicals archive ?
Predictive value of attenuation coefficients measured as Hounsfield units on noncontrast computed tomography during flexible ureteroscopy with holmium laser lithotripsy: a single-center experience.
Most soft tissues fall between 30 and 100 Hounsfield units, so cells labeled with the new compound were expected to stand out.
The examination and evaluation involved both morphological analysis and bone density analysis in Hounsfield units.
Correlation between CT measure of percent emphysema (using cutoff of -950 Hounsfield units, ([LAA.
Imaging findings include well-delineated homogeneous mass with density between 70 and 120 Hounsfield units.
1-4,14,17,18) Because of the fact that adenomas often have intracytoplasmic fat, resulting in lower attenuation, measurement of the attenuation value in Hounsfield units is helpful in distinguishing adenomas from nonadenomas (14,18); tumors with attenuation values of less than 10 Hounsfield units on an unenhanced CT are often diagnostic of adrenocortical adenomas (Figure 1, A).
Of the 1,115 women evaluated, 124 (11%) went on to develop GDM and 75 (7%) met the CT definition for NAFLD (liver attenuation less than or equal to 40 Hounsfield units on CT scan) by the 25-year follow-up, when they were a median age of 50-51 years.
It showed an encapsulated, non-enhancing mass with homogenous low attenuat-ion that measured -30 Hounsfield units.
Intrathecal digital tendon structures were visualized at low density ranging from 150 to 240 Hounsfield Units (HU), and the synovial cavity was visualized with CM (>2000 HU).
9 Future studies should have the provision of using bone density values measured in Hounsfield Units or from other data obtained from patient specific scans.
patient table) and the patient's tissue m-map are generated from a fast (potentially low-dose) 3D CT scan and then rescale Hounsfield units to 511-keV linear attenuation coefficients.