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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
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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 |