E - Glossary of Terms

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E - Glossary of Terms

early effect	A radiation response that occurs within minutes or days after radiation exposure.
ec	Prefix meaning out or outside of.
eccentric	(ek-sen'trik) situated off center, not having same centre, opposed to concentric.
eccrine gland	(ek´rin) A sweat gland that functions in thermoregulation.
ecchymosis	An ecchymosis (ek-e-mow-sis)refers to a subcutaneous hematoma larger than 1 centimeter, commonly called a bruise. It can be located both in the skin as well as in a mucous membrane.
ecto	(ek'to) Prefix denoting without, on the outer side, external eg ectopic is out of normal position.
ectoderm	(ek´to-derm) The outermost of the three primary germ layers of an embryo.
ectomy	(ek'to-me) Suffix denoting surgical removal eg cholecystectomy.
ectopic	(ek-top´ik) Greek ek = out, and topos = place, hence out of place.
eddy current	A current opposing the magnetic field that induced it, creating a loss of transformer efficiency.
edema	(e-de´ma) An excessive accumulation of fluid in the body tissues.
edentulous	(e-dent'tu-lus) Without teeth.
edge enhancement	The accentuation of the interface between different tissues.
edge-response function (ERF)	The mathematical expression‎ of the ability of the computed tomo¬graphic scanner to reproduce a high-contrast edge with accuracy.
Edison, Thomas	Inventor Thomas Edison invented fluoroscopy and the fluoroscopic screen in 1896.
effaced	Wiped out or obliterated.
effective atomic number	The weighted average atomic number for the different elements of a material.
effective dose (E)	The sum over specified tissues of the products of the equivalent dose in a tissue (FIt) and the weighting factor for the tissue (Wt).
effective dose equivalent (Hp )	Sum of the products of the dose equivalent to a tissue (FIt) and the weighting factors (Wi) applicable to each of the tissues irradiated. The values (Wi) are different for effective dose and effective dose equivalent.
effective focal-spot size	The area projected onto the patient and the image receptor.
effective source size	The apparent dimensions as viewed along the beam axis of that portion of the source from which ionising radiation is emitted.
effector	(e-fek´tor) An organ, such as a gland or muscle, that responds to a motor stimulation.
efferent	(ef´er-ent) Conveying away from the center of an organ or structure.
efferent arteriole	(ef'er-ent ar-tir´e-ol) An arteriole of the renal vascular system that conducts blood away from the glomerulus of a nephron.
efferent ductules	(ef'er-ent duk´toolz) A series of coiled tubules through which spermatozoa are transported from the rete testis to the epididymis.
efferent neuron	(ef'er-ent new'-ron) See motor neuron.
effusion	(ef-u'zhun) Escape of fluid from vessels into tissues or cavities of the body.
egest	(e-jest') To expel or excrete waste material from body, opposed to ingest.
elastic fibres	(e-las´tik) Protein strands that are found in certain connective tissue that have contractile properties.
elbow	The elbow is the region surrounding the elbow-joint.
elbow joint	The large joint for the upper extremity, between the distal humerus and the proximal radius and ulna.
elective booking	A safeguard against the irradiation of an unsuspected pregnancy.
electrical energy	The work that can be done when an electron or an electronic charge moves through an electric potential.
electric circuit	The path of the electron flow from the generating source through the various components and back again.
electric current	The flow of electrons.
electric field	The lines of force exerted on charged ions in the tissues by the electrodes that cause charged particles to move from one pole to another.
electricity	A form of energy created by the activity of electrons and other subatomic particles in motion.
electrification	The process of adding or removing electrons from a substance.
electrified object	An object that has too few or too many electrons.
electrode	An electrical terminal or connector.
electromagnet	Coil or wire wrapped around an iron core, which intensifies the magnetic field.
electromagnetic energy	Type of energy in x-rays, radio waves, microwaves, and visible light.
electromagnetic radiation	Oscillating electric and magnetic fields that travel in a vacuum with the velocity of light. Includes x-rays, gamma rays, and some non-ionizing radiation (such as ultraviolet, visible, infrared, and radio waves).
electromagnetic spectrum	The broad range of wavelengths of radiation extending from very short wavelength cosmic rays to the very long wavelength radio waves that travel in straight lines and are characterised by a wave motion, and travel through a vacuum at the speed of light. The continuum of electromagnetic energy.
electromotive force	Electric potential; measured in volts (V).
electron	Elementary particle with one negative charge. Electrons surround the positively charged nucleus and determine the chemical properties of the atom.Small negatively charged particles that orbit around the nucleus of an atom.
electron density	The number of electrons per cm3 in a material. Soft tissues including fat have very similar electron density; bone is nearly twice as high.
electron optics	The engineering aspects of maintaining proper electron travel.
electron spin	The momentum of a particle of an atom in a fixed pattern.
electron binding energy	The strength of attachment of an electron to the nucleus.
electron volt (eV)	The energy gained by an electron as it is accelerated through a potential difference of 1 volt.
electrostatics	Study of fixed or stationary electric charge.
element	An atom having the same atomic number and same chemical properties. A substance that cannot be broken down further without changing its chemical properties.
elemental mass	The characteristic mass of an element, determined by the relative abundance of isotopes and their respective atomic masses.
elephantiasis	(el''e-fan-ti'a-sis) Chronic disease in which affected part undergoes extensive enlargement and skin becomes thick, rough and fissured so that it resembles an elephants hide.
elongation	An image made to appear longer than it really is because the inclined object is not located on the central x-ray beam.
em	(em) Prefix meaning in eg empyema is pus in a cavity.
emaciation	(e-ma''si-a'shun) Wasted, condition of becoming lean or emaciated.
embolism	(em'bo-lizm) Obstruction of a blood vessel by an embolus or plug carried in from a larger vessel, usually a blood clot.
embolus	(em'bo-lus) Clot of blood, air bubble, or other obstructive plug conveyed by bloodstream and lodging in a smaller vessel.
embryologic effect	Damage occurring as a result of an organism being exposed to ionising radiation during its embryonic stage of development.
embryology	(em´´bre-ol´o-je) The study of prenatal development from conception through the eighth week in utero.
emesis	(em'e-sis) Act of vomiting.
emetic	(e-met'ik) Any means employed to produce vomiting.
emphysema	(em´´fe-se´ma) A lung disease in which the alveoli are destroyed and the remaining alveoli become larger. It results in decreased vital capacity and increased airway resistance.
empyema	(em''pi-e'mah) Accumulation of pus in a body cavity, most frequently in pleural cavity.
emulsification	(e-mul´´si-fi-ka´shun) The process of producing an emulsion or fine suspension; in the small intestine, fat globules are emulsified by the detergent action of bile.
emulsion	(e-mul'shun) Oily or resinous substance suspended in an aqueous liquid by mucilaginous or other emulsifying agent. In medical imaging the material with which X-rays or light photons from screens interact and transfer information - A suspension of silver bromide crystals in thin gelatin coating on the film base. It is characterised by its speed and latitude.
en	(en) Prefix meaning in eg encysted is enclosed in a sac.
enamel	(e-nam´el) The outer dense substance covering the crown of a tooth.
encephalo	(en-sef'a-lo) Prefix signifying relation to the brain.
encephalography	(en-sef''a-log'ra-fe) Radiographic examination of brain after ventricles have been filled with contrast medium.
encysted	(en-sist'ed) Enclosed in a sac or cyst.
endemic	Native to a particular country, nation, or region.
endo	(en'do) Prefix meaning within; occupying an inward position eg endocarditis is inflammation of lining membrane of heart.
endocardium	(en´´do-kar´de-um) The endothelial lining of the heart chambers and valves.
endocervical canal	The portion of the uterine cavity that lies within the cervix - the passage that connects the vaginal canal with the main uterine cavity.
endochondral bone	(en´´do-kon´dral) Denoting bones that develop as hyaline cartilage models first and that are then ossified.
endocrine	(en´do-krin) secreting internally, as ductless glands. Pertaining to endocrine glands such as pituitary, thyroid, pineal body and lymphatic system.
endoderm	(en´do-derm) The innermost of the three primary germ layers of an embryo.
endogenous	(en-doj´e-nus) Denoting a product or process arising from within the body (as opposed to exogenous products or influences from external sources).
endolymph	(en´do-limf) A fluid within the membranous labyrinth and cochlear duct of the inner ear that aids in the conduction of vibrations involved in hearing and the maintenance of equilibrium.
endometrium	(en´´do-me´tre-um) The inner lining of the uterus.
endoplasmic reticulum	(en-do-plaz´mik re-tik´yuu-lum) A channel or series of channels that allows the nucleus to communicate with the cytoplasm.
endoscopic retrograde cholangiopancreatography - ERCP	Radiographic examination of pancreatic and biliary duct performed by injection of contrast media into these ducts, contrast is injected through a catheter positioned with use of fiberoptic scope.
endoscopy	(en-dos'ko-pe) Visual inspection of gastrointestinal tract with fiberoptic scope.
endosteal	(en-dos'te-al) Of or pertaining to endosteum, vascular tissue lining medullary cavity of bones.
endothelium	(en´´do-the´le-um) The layer of epithelial tissue that forms the thin inner lining of blood vessels and heart chambers.
endotracheal tube	An airway catheter that is inserted into the trachea to assist breathing and ventilation of the lung. ET tubes are used with mechanical ventilation for critical patients.
enema	(en'e-mah) Fluid injected into rectum to clean the bowel or to administer food or a drug.
energy	The ability to do work; measured in joules (J). Energy levels The orbits around the nucleus that contain a designated number of electrons.
energy subtraction	A technique that uses the two x-ray beams alternately to provide a subtraction image resulting from differences in photoelectric interaction.
engorgement	Congestion of a blood vessel or tissue with blood or other fluid.
enteric	(en-ter´ik) The term referring to the small intestine.
enteritis	(en-ter-i'tis) Inflammation of intestines, specifically of small intestine.
entero	(en'ter-o) Prefix denoting relation to intestine eg enteroptosis is a dropping or downward displacement of intestines.
enterostomy	(en''ter-os'to-me) Surgical formation of an opening into intestine through the abdominal wall.
entrance roller	A roller that grips the film to begin its trip through the processor.
entrance skin exposure (ESE)	X-ray exposure to the skin; expressed in milliroentgen (mR).
enuresis	(en''u-re'sis) Involuntary discharge of urine, incontinence of urine, especially at night.
envelope	A glass tube surrounding the electrodes of an X-ray tube inside which a vacuum is maintained.
enzyme	A molecule that is necessary in small quantities to allow a biochemical reaction to continue even though it does not directly enter into the reaction.
epi	(ep'i) Prefix meaning on, above, on the outside, over eg epigastric means situated above the stomach.
epicardium	(ep´´i-kar´de-um) A thin, outer layer of the heart; also called the visceral pericardium.
epicondyle	(ep´´i-kon´di-l) A projection of bone above a condyle.
epidermis	(ep´´i-der´mis) The outermost layer of the skin, composed of several stratified squamous epithelial layers.
epidemiology	The study of the occurrence, distribution, and causes of disease in humans.
epididymis	(ep´´i-did´i-mis) A highly coiled tube located along the posterior border of the testis. It stores spermatozoa and transports them from the seminiferous tubules of the testis to the ductus deferens.
epidural space	(ep´´i-door´al) A space between the spinal dura mater and the bone of the vertebral canal. (epidural anasthetic - a liquid anastetic is injected into the extra(epi)dural space. insertion of hollow needle through the skin of the back and the ligamentum flavum. The needle is not advanced further as for alumbar puncture)
epigastric region	Greek epi = upon, and gaster = belly, hence, the upper median zone of the abdomen (see hypochondriac, umbilical, lumbar, inguinal and hypogastric)
epiglottis	(ep´´i-glot´is) A leaf like structure positioned on top of the larynx. It covers the glottis during swallowing.
epilation	The loss of hair.
epiphyseal plate	(ep´´i-fiz´e-al) A hyaline cartilaginous layer located between the epiphysis and diaphysis of a long bone. It functions as a longitudinal growing region.
epiphysis	(e-pif´i-sis) The end segment of a long bone, separated from the diaphysis early in life by an epiphyseal plate but later becoming part of the larger bone once the plate ossifies.
epiphysitis	(e-pif''i-si'tis) Inflammation of an epiphysis or of cartilage separating it from diaphysis.
epiploic	adjective, Greek epiploon = a net, which the greater omentum resembles with fat entangled in it. Synonymous with omental,mesenteric and ligamentous.
episiotomy	(e-pis''-te-ot´o-me) An incision of the perineum at the end of the second stage of labor to facilitate delivery and to avoid tearing the perineum.
epithelial tissue	(ep´´i-the´le-al) One of the four basic tissue types; the type of tissue that covers or lines all exposed body surfaces.
epithelium	The covering tissue that lines all exposed surfaces of the body, both exterior and interior.
eponychium	(ep´´o-nik´e-um) The thin layer of stratum corneum of the epidermis of the skin that overlaps and protects the lunula of the nail.
equilibrium half value layer	The greatest thickness of materials required to reduce the intensity of a polychromatic beam of radiation by a factor of two.
ERCP	see endoscopic retrograde cholangiopancreatography.
erect	Standing upright
erector spinea muscle	Intermediate muscles of the back that produce extention in the vertebral column. It originates from the sacrum, iliac crest, and spines of the lumbar and eleventh and twelfth thoracic vertebrae, splitting into the iliocostals, longissimus, and spinalis muscles.
erg (Joule)	The unit of energy and work.
erosion	(e-ro'zhun) Irregular or uneven wearing or eating away, beginning at surface of a part, as an ulcerative or necrotic process.
eructation	(e''ruk-ta'shun) Act of dishcharging or belching gas from the stomach, a belch.
erythema	(er''i-the'mah) Morbid redness of skin caused by capillary congestion resulting from irradiation or any form of inflammatory process. A sunburnlike reddening of the skin
erythrocyte	(e-rith´ro-si'-t) A red blood cell.
erythropoietin	Substance(s) serving as the humoral regulator of red blood cell formation.
etiology	(e''ti-ol'o-je) Science or doctrine of causation; investigation or assignment of cause of a disease.
ethmoid sinus	The paranasal sinus located within the ethmoid bone, between the orbits, below the brain, and above the nasal cavity.
eu	(u) Prefix signifying well eg eupnea is normal breathing opposed to dyspnea.
EUR/OPE	Electrons used in reduction/oxidation pro¬cedure electrons.
eustachian canal	(yoo-sta´ke-an) A hollow cartilagenous tube connecting the tympanic cavity (middle ear) and the nasopharynx. An open tube can equilibrate the pressure in the middle ear. Yawning opens the tube to allow the ears to "pop!" when changing altitude.
evagination	(e-vaj''i-na'shun) Turned inside out, protusion of a part or organ.
eventration	(e''ven-tra'shun) Protrusion of intestines from abdomen.
eversion	(e-ver´zhun) A movement of the foot in which the sole is turned outward (laterally).
evert	(e-vert) To turn outward.
ex	(eks) Prefix denoting out, out of, or away from eg excavation is hollowing out.
exacerbation	Increase in the severity of a disease or any of its symptoms.
excess risk	The difference between the observed and the expected number of cases.
excitation	The addition of energy to a system by raising the energy of electrons with the use of x-rays.
excreta	(eks-kre'tah) Waste materials excreted or separated out by an organ, waste products cast out from body.
excretion	(eks-kre'shun) Throwing off of waste matter.
excretory	(eks'kre-to''re) Of or pertaining to excretion.
exit radiation	The X-rays that remain after the beam exits through the patient.
exo	(sk'so) Prefix meaning outward or outside eg exogenous is growing from or on the outside of a part of body.
exocrine	(ek´so-krin) A cell or group of cells that secretes its product to an epithelial surface, directly or through ducts.
exogenous	Arising from outside the body.
exophthalmos	Abnormal protrusion of the eyeball.
exostosis	(eks''os-to'sis) Spur, or osseous outgrowth from a bone or tooth.
expiration	(ek´´spi-ra´shun) The process of expelling air from the lungs through breathing out; also called exhalation.
expiration date	The date after which the manufacturer of a film will no longer maintain the warranty for quality control.
exponent	Superscript or power to which 10 is raised in scientific notation.
exponential form	Power-of-10 notation.
exposed matter	The matter that intercepts radiation and absorbs part or all of it; irradiated matter.
exposure	The measure of the ionisation produced in air by X-rays or gamma rays. The quantity of radiation intensity expressed in roentgen (R), Coulombs per kilogram (C/kg), or air kerma (Gy).
exposure chart	A chart on which is plotted one or more curves which indicate exposures for specified source or X-ray tube, product, film, film density and source to film distance for various product thicknesses. See a sample exposure chart
exposure factors	The factors that influence and determine the quantity and quality of x-radiation to which the patient is exposed.
exposure index	Exposure index (EI) is the measure of the amount of exposure received by the image receptor. Exposure Index
exposure latitude	The ability of a film to accommodate variations in density occurring as a result of differences in thickness of an object.
exposure linearity	The ability of a radiographic unit to produce a constant radiation output for various combinations of mA and exposure time.
extension	(ek-sten´shun) A movement that increases the angle between parts of a joint. (Usually straighten)
extensor	(A muscle that, upon contraction, increases the angle of a joint.
external	(superficial) Located on or toward the surface.
external acoustic meatus	(a-koo´stik me-a´tus) An opening through the temporal bone that connects with the tympanum and the middle-ear chamber and through which sound vibrations pass; also called the external auditory meatus.
external auditory canal	The opening in the external surface of the temporal bone, behind the condyle of the mandible and in front of the mastoid air cells that conducts air and sound toward the tympanic membrane.
external iliac artery	Artery which originates from the common iliac and branches into the inferior epigastric and deep circumflex iliac arteries.
external iliac vein	The continuation of the femoral vein, beginning at the level of the inguinal ligament, and joining the internal iliac vein at the sacroiliac articulation to form the common iliac vein.
external oblique muscles	Muscles that run from the lower eight ribs at the costal cartilages to the crest of ilium and linea alba, that are responsible for flexing and rotating the torso and vertebral column.
exteroceptors	(ek´´ste-ro-sep´torz) Sensory receptors that are sensitive to changes in the external environment (as opposed to interoceptors).
extinction time	The time required to end an exposure.
extra	(eks'tra) Prefix meaning on outside, beyond, in addition eg extragastric is situated or occuring outside the stomach.
extra focal radiation / off-focus radiation	Electrons that bounce off the focal spot and land on other areas of the target.
extramedullary hematopoiesis	Formation of red blood cells outside of the bone marrow.
extraocular muscles	(ek´´stra-ok´yuu-lar) The muscles that insert into the sclera of the eye and that act to change the position of the eye in its orbit (as opposed to the intraocular muscles, such as those of the iris and ciliary body within the eye).
extrapolation	The estimation of a value beyond the range of known values.
extravasation	(eks-trav''a-sa'shun) Escape of fluids from a vessel into surrounding tissues.
extrinsic	(eks-trin´sik) Pertaining to an outside or external origin.
exudate	(eks'u-dat) Adventitious material exuded or dishcharged on injured or diseased tissues.