O - Glossary of Terms

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O - Glossary of Terms

obese	(o-b-es´) Excessively fat.
object plane	The plane in which the anatomic struc¬tures that are to be imaged lie.
object-to-image receptor distance	The distance from the image receptor to the object that is to be imaged.
obstetrics	(ob-stet'riks) Science dealing with pregnancy and parturition; management of childbirth.
occiput	(ok'si-put) Back part of cranium.
occlusal	(o-klu'sal) Of or pertaining to biting surface of a tooth or teeth.
occlusal line	(o-klu'sal) Imaginary line passing through head at and parallel with biting surface of teeth.
occlusion	(o-klu'zhun) Act of closing or occluding, or state of being closed or occluded, as in a stricture of a normal passage; bringing into contact of opposing surfaces of upper and lower teeth.
occupational dose	The dose received by an individual in a restricted area during the course of employment in which the individual's assigned duties involve exposure to radiation.
occupational exposure	Radiation exposure received by radiation workers.
oedema	(e-de'mah) See edema.
off-focus radiation	X-rays produced in the anode but not at the focal spot.
off-level grid	An artifact produced by having an improperly positioned radiographic tube, not by having an improperly positioned grid.
olfactory	(ol-fak´to-re) Pertaining to the sense of smell.
olfactory bulb	(An aggregation of sensory neurons of an olfactory nerve, lying inferior to the frontal lobe of the cerebrum on either lateral side of the crista galli of the ethmoid bone.
olfactory tract	(The olfactory sensory tract of axons that conveys impulses from the olfactory bulb to the olfactory portion of the cerebral cortex.
oligemia	Decreased blood flow.
oligodendrocyte	(ol´´i-go-den´dro-s-ite) A type of neuroglial cell concerned with the formation of the myelin of nerve fibers within the central nervous system.
-ology	(-ol'o-je) Suffix meaning a science or branch of knowledge; as radiology, science dealing with diagnostic and therapeutic application of X-radiation.
-oma	(-o'mah) Suffix denoting morbid condition of some type, usually a tumor, such as carcinoma. fibroma. myoma, sarcoma.
omental	synonymous with mesenteric, epiploic and ligamentous.
omentum	(o-men'tum) Latin = apron, Free folds of peritoneum that connect stomach with adjacent organs; apronlike great omentum hanging downward in front of small intestines.
oncology	(on-kol´o-je) The study of tumors.
1% voltage ripple	High-frequency generators that have higher X-ray quantity and quality.
100% voltage ripple	Single-phase power in which the voltage varies from zero to its maximum value.
oocytes	Primordial follicles that grow to encapsulate oogonia.
opacity	The capacity to attenuate an X-ray beam; the degree of attenuation of the X-ray beam, usually expressed in terms of the attenuation of one absorber to another. In a radiograph, an opacity is a circumscribed area that appears nearly white (i.e., denser) than its surroundings. Use of the term opacity does not imply location; opacity may be parenchymal, pleural, within the chest wall, or external to the patient.
opaque	A surface that does not allow the passage of light.
open filament	A condition that results when the filament becomes thinner and breaks.
operating console	Console that allows the radiologic technologist to control the X-ray tube current and voltage so that the useful x-ray beam is of proper quantity and quality.
operating system	The series of instructions that organizes the course of data through the computer to solve a particular problem.
optic	(op´tik) Pertaining to the eye.
optic chiasma	(ki-az´ma) An X-shaped structure on the inferior aspect of the brain, anterior to the pituitary gland, where there is a partial crossing over of fibers in the optic nerves; also called the optic chiasm.
optic disc	(A small region of the retina where the fibers of the ganglion neurons exit from the eyeball to form the optic nerve; also called the blind spot.
optic tract	A bundle of sensory axons located between the optic chiasma and the thalamus that functions to convey visual impulses from the photoreceptors within the eye.
optical density	The degree of blackening of a radiograph.
optical disk	A removable disk that uses laser technology to write and read data.
optimum	(op'ti-mum) Best; most conducive to success; condition that is best or most favorable; most suitable degree, quantity, or factor for attainment of a given end.
oral	(o'ral) Latin oris = a mouth. Pertaining to the mouth.
ora serrata	The jagged peripheral margin of the retina.
orbitomeatal line	(orbi-to-me-a-tal) Imaginary line extending from outer canthus to center of tragus; it is used in radiography for localization purposes.
orchio	Prefix denoting testes.
ordered pairs	Notation for coordinates in which the first number of the pair represents a distance along the x-axis and the second number indicates a distance up the y-axis.
organ	A structure consisting of two or more tissues that performs a specific function.
organelle	(or´´ga-nel´) A minute living structure of a cell with a specific function.
organic	(or-gan'ik) Of or pertaining to an organ or organs; consisting of or affecting organic structure; also (in chemistry) pertaining to carbon compounds, those of artificial origin as well as those derived from living organisms.
organism	An individual living creature.
organ of Corti	(kor´te) See spiral organ.
orifice	(or´i-fis) An opening into a body cavity or tube.
origin	The place of muscle attachment-usually the more stationary point or the proximal bone; opposite the insertion. The point where two axes meet on a graph
organs	A collection of tissues of similar structure and function.
organ system	A combination of tissues and organs that forms an overall integrated organization.
organic molecule	A molecule that is life supporting and contains carbon.
oropharynx	(o´´ro-far´ingks) The second portion of the pharynx, located posterior to the oral cavity and extending from the soft palate to the hyoid bone.
ortho-	Prefix meaning straight or normal; correct or true; as orthodontic, orthographic, orthuria, and orthostatic, standing upright, caused by or pertaining to standing erect.
orthochromatic	Referring to blue- or green-sensitive film; usually exposed with rare earth screen.
orthopedics	(or"tho-pe'diks) Branch surgery dealing with correction or prevention of deformities and with treatment diseases of bones.
os	mouth; any mouthlike orifice; as os uteri.
os	bone eg os calcis, os coxae, os magnum.
os innominatum	(os in-nom"i-na'tum) Innominate bone; old term for os coxa.
osis	(-o'sis) Suffix denoting state or condition; as psychosis, stenosis, sclerosis.
osmolality	(oz´´mo-lal´i-te) A measure of the total concentration of a solution; the number of moles of solute per kilogram of solvent.
osmosis	(oz-mo´sis) The passage of solvent (water) from a more dilute to a more concentrated solution through a membrane that is more permeable to water than to the solute.
osseous tissue	(os´e-us) Greek osteon = bone.
ossicle	(os´i-kul) One of the three bones of the middle ear; also called the auditory ossicle.
ossification	(os´´i-fi-ka´shun) The process of bone tissue formation.
osteo-	(os'te-o-) Prefix denoting relation to bone; as osteoma, a benign bony tumor.
osteoblast	(os´te-o-blast) A bone-forming cell.
osteoblastic	Forming bony tissue
osteoclast	(os´te-o-klast) A cell that causes erosion and resorption of bone tissue.
osteoclastic	Destroying bone.
osteocyte	(os´te-o-s-it) A mature bone cell.
osteology	(os´´te-ol´o-je) The study of the structure and function of bone and the entire skeleton.
osteolytic	Destroying bone
osteomalacia	(os´´te-o-ma-la´sha) Softening of bones due to a deficiency of vitamin D and calcium.
osteomyelitis	(os"te-o-mi-el-i'ts) Inflammation of marrow and medullary portion of a bone.
osteon	(os´te-on) A group of osteocytes and concentric lamellae surrounding a central canal, constituting the basic unit of structure in osseous tissue; also called a haversian system.
osteoporosis	(os´´te-o-po-ro´sis) Demineralization of bone, seen most commonly in postmenopausal women and patients who are inactive or paralyzed. It may be accompanied by pain, loss of stature, and other deformities and fractures.
ostium	(os'ti-um) Small mouthlike orifice especially opening into a tubular passage such as an oviduct.
(o)-stomy	Suffix signifying surgical formation of an artificial mouth or opening into some part or between two parts; as enterostomy, formation of an opening into intestines through abdominal wall, and gastroenterostomy, formation of an artificial opening between stomach and small intestine.
otic	(o'tik) Of or pertaining to ear; auditory.
otitis	(o-ti'tis) Inflammation of ear; as otitis media, inflammation of middle ear.
otoliths	(o´to-liths) Small, hardened particles of calcium carbonate in the saccule and utricle of the inner ear, associated with the receptors of equilibrium; also called statoconia.
(o)-tomy	Suffix signifying surgical incision of, usually for the purpose of draining; as cholecystotomv, nephrotomy, osteotomy.
outcome analysis	Image interpretation that involves reconciling the patient's ultimate disease condition with the radiologist's diagnosis.
outer ear	The outer portion of the ear, consisting of the auricle and the external auditory canal.
output	The process of transferring the results of a computation from primary memory to storage or the user.
oval window	An oval opening in the bony wall between the middle and inner ear, into which the footplate of the stapes fits; also called the vestibular window.
ovarian ligament	(lig´a-ment) A cordlike connective tissue that attaches the ovary to the uterus.
ovary	(o´va-re) The female gonad in which ova and certain sexual hormones are produced.
overcoat	A protective covering of gelatin that encloses the emulsion.
overexposed	Referring to a radiograph that is too dark because too much X-radiation reached the image receptor.
oviduct	(o´vi-dukt) The tube that transports ova from the ovary to the uterus; also called the uterine tube or fallopian tube.
ovum	The mature germ cell found in a female
oxidation	A reaction that produces an electron.
oxycephalic	(ok"si-se-fal'ik) Having an unusually high vertex; a steeple-shaped head.
oxygen enhancement ratio (OER)	The ratio of the dose necessary to produce a given effect under anoxic conditions to the dose necessary to produce the same effect under aerobic conditions