subtraction

subtraction
A technique used to enhance detectability of opacified anatomic structures on radiographic or scintigraphic images; a negative of an image made before introduction of contrast medium or radionuclide is photographically or electronically removed from a later image; commonly used in cerebral angiography. SEE ALSO: digital s. angiography, mask.
- energy s. digital radiography using higher- and lower-energy exposures, either by double exposure at 2-kV levels or by interposing a copper filter that absorbs the lower-energy photons between two phosphor plates, with computer calculation of high-Z and low-Z images (bone and soft tissues, respectively); makes use of the fact that lower-energy x-rays are absorbed by more high-Z substances, such as calcium and copper, because of the photoelectric effect. SEE ALSO: Z, photoelectric effect, phosphor plate.

* * *

sub·trac·tion (səb-trakґshən) the removal of something from a group.

Medical dictionary. 2011.

Игры ⚽ Поможем написать реферат
Synonyms:

Look at other dictionaries:

  • Subtraction — Sub*trac tion, n. [L. subtractio a drawing back. See {Subtract}, and cf. {Substraction}.] 1. The act or operation of subtracting or taking away a part. [1913 Webster] 2. (Math.) The taking of a lesser number or quantity from a greater of the same …   The Collaborative International Dictionary of English

  • Subtraction — Subtraction, subtrahiren, eine der 4 arithmetischen Species, welche von 2 gegebenen Größen (dem Minuendus d.h. dem zu Verkleinernden, und Subtrahendus d.h. Abzuziehenden) die Differenz od. den Unterschied aufsucht; ihr Zeichen ist – (lat. minus,… …   Herders Conversations-Lexikon

  • subtraction — I noun abstraction, ademption, curtailment, decrease, decrement, deduction, diminution, discount, exception, lessening, reduction, removal, retrenchment, shortening, shrinkage, subduction, withdrawal II index curtailment, decrease, decrement,… …   Law dictionary

  • subtraction — c.1400, withdrawal, removal, from L.L. subtractionem (nom. subtractio) a drawing back, taking away, from pp. stem of L. subtrahere take away, draw off, from sub from under (see SUB (Cf. sub )) + trahere to pull, draw (see TRACT (Cf …   Etymology dictionary

  • subtraction — [səb trak′shən] n. [ML subtractio < LL(Ec), a drawing back] a subtracting or being subtracted; esp., the mathematical process of finding the difference between two numbers or quantities …   English World dictionary

  • Subtraction — 5 − 2 = 3 (verbally, five minus two equals three ) …   Wikipedia

  • subtraction — The offense of withholding or withdrawing from another man what by law he is entitled to. There are various descriptions of this offense, of which the principal are as follows: (1) Subtraction of suit and services, which is a species of injury… …   Black's law dictionary

  • subtraction — Compound Com pound, a. [OE. compouned, p. p. of compounen. See {Compound}, v. t.] Composed of two or more elements, ingredients, parts; produced by the union of several ingredients, parts, or things; composite; as, a compound word. [1913 Webster] …   The Collaborative International Dictionary of English

  • subtraction — noun Etymology: Middle English subtraccion, from Anglo French sustraction, subtraction, from Late Latin subtraction , subtractio, from Latin subtrahere Date: 15th century an act, operation, or instance of subtracting: as a. the withdrawing or… …   New Collegiate Dictionary

  • subtraction — subtract UK US /səbˈtrækt/ verb [T] ► to take a number or amount away from another number or amount: subtract sth from sth »The costs of manufacturing are subtracted from revenue. subtraction noun [C or U] ► »Net output can be calculated by… …   Financial and business terms

  • subtraction — n. to do subtraction * * * [səb trækʃ(ə)n] to do subtraction …   Combinatory dictionary

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”