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radiographyy
Question | Answer |
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radiant | energy waves that are produced, charged, and emitted from a common center in the dental radiation tube |
x-ray tube | produces x-rays |
cathode | (negative pole) electrode in the vacuum tube that serves as the electron source |
filament | (fine thread) tungsten coil in the cathode focusing cup that generated the electrons |
anode | (positive pole) the target for the electron barrage to convert the electron force into photons |
focal spot | target area where rays are projected to make the primary beam, or central beam |
collimator | (to align) a device used to regulate the beams exit from the tube into parallel rays and to avoid stray radiation |
PID | position inticating device |
aperture | (opening or port) opening in the lead collimator disk that regulates the size of the primary beam |
filter | aluminum disks that are placed between the collimator attachment and the exit window of the tube to absorb weak radiation |
inherent filtration | all filtration devices that filter weak, longer-wavelength x-rays |
added filtration | filtration placed outside the tube head to meet saftey standards |
total filtration | sum of inherent and added filtration, expressed in mm of aluminum equivlent |
milliampere control | (one-thousand of an ampere) also known as milliameter; an increase in millamperage increases the amount of electrons available and darkens the radiograph |
kilovolt power | (volt unit) controls the force that attracts the electrons to the anode; helps determine the penetrating power and the quality/energy of the radiation rays |
exposure time | duration of the intercal during which current wil pass through the x-ray tube |
target-film distance | distance of the film surface from the source of radiation (target or focal spot) |
target-object distance | distance between the anode target and the abject to be radiographed |
film speed | A (slowest) to F (fastest) speed; faster film requires less radiation exposure time for the patient |
primary radiation | central ray of radiation emitting from the tube head and PID |
secondary radiation | radiation given off from other matter that is exposed to the primary beam |
scattered radiation | radiation radiation deflected from its path during its passage through matter |
stray radiation | also called leakage, any radiation other than the useful beam produced from the tube head |
remnant radiation | radiation rays that reachthe film target after passing through the subject part being radiographed |
sensitivity | ability of x-rays to penetrate and possibly ionize |
cumulative effect | long-term outcome of radiation |
latent period | the time intercal between the exposure and the effect or its detection |
mutation effect | abnormal growth or development as a result of radiation causing a genetic change |
acute radiation exposure | radiation occurring from a massive, short-term ionizing dose, such as accidental exposure or explosion of radiation material |
chronic radiation exposure | accumulated radiation effects from continual or frequent small exposures absorbed over a period of time |
ALARA | a policy of using the lowest amount of radiation exposure possible |
maximum permissable dose | highest rate of exposure permissible for the occupationally exposed person |
roentgen (R) | the basic unit of exposure to radiation; the amount of e-radiation or gamma radiation needed to ionize 1cc of air at standard pressure and temp conditions |
rad (radiation absorbed dose) | the unit of absorbed radiation dose equal to 100 ergs per gram of tissue |
rem (roentgen equivalent measure) | the unit of ionizing radiation needed to produce the same biological effect as one roenthen of radiation |
erythema dose | radiation overdose that produces temporary redness of the skin |
dosimeter | (giving measure) radiation-monitoring device with ionizing chamber or a device to indicate exposure and measure accumulated doses of radiation |
lead apron/thyrocervical collar | patient apparel with lead protection for genetic cells in the torso and the thyroid glands in the cervical area |
lead barriers, sheilds | devices ised by operators to block out scattered radiation |
phantom | practice manikin containing tooth and head structures to imitate actual condition |
periapical film packet | used for the intraoral periapical veiw of the entire tooth or teeth in a given area along with adjacent tissues and oral structures |
bitewing film packet | film used to record the crown and interproximal veiws of both arches while in occlusion; used intraorally |
occlusal film packet | film that may be used intraorally or extraorally to expose large areas |
extraoral films | radiographs exposed outside the oral cavity; larger in size and loaded in a film cassette or wrapped for protection from light rays |
cephalometric | (head measure) also called headplates; extraoral radiographs of the head are used in orthodontic, oral surgery, and sometimes in prosthodontic dentistry |
cephalostat | a device used to stabilize the parient's head in a plane parallel to the film and at right angles to the central ray if the x-ray beam |
panoramic radiograph | a special radiograph producing the entire dentition with surrounding structures on one film |
intensifying screen | a layer of flourescent crystals or calcium tunstate within the cassette that gives off a bluish light when exposed to radiation |
contrast | variations in shades from black to white |
density | amount of film blackening associated with the percentage of light trasmitted through a film |
detail | point-to-point delineation or veiw of tiny structures in a radiograph image |
definition | outline sharpness and clarity of image exhibited on a radiograph |
penumbra | poor definition or fuzzy outlines |
radiolucent | (ray, shine) describes a radiograph that appears dark; or the ability of a substance to permit passage of x-rays, thereby cause the radiographic film to darken |
radiopaque | (ray, dark) the portion of the radiograph that appears light, or the ability of a substance to resist x-ray penetration, thereby causing a light area on the film |
bisecting angle | the cental x-ray beam is directly perpendicular with an imaginary bisecting line of the angle formed by the plane of the film and the long axis of the tooth |
paralleling | the film packet is placed parallel to the long axis of the tooth and at a right angle to the central x-ray beam |
CCD (charged coupled device) | a solid-state sensor that may or may not be wired to the computer work station, barrier-wrapped and inserted into a positioning device for placement and exposure in the mouth |
PSP (photostimulable phosphor device) | an indirect sensor storage plate that absorbs radiation to complete a latent image |
indirect dental radiography digital image | x-ray image already processed by the usual method, scanned by an adapter in the database |
electronic image processing | operator's manipulation of the digital image, consisting of contrast, brightness, image reversal, embossing, and grayness to enhance, measure, compare, or obtain information |
digital subtraction radiography | digital comparison of the image to a precious radiograph, subtracting all that is the same and analyzing or comparing the remainder |
sagittal plane | also called midsaggital plane; imaginary vertical line bisecting the face into a right half and left half; important during exposure to determine positioning of the patient |
ala tragus line | imaginary line fromt he ala (wing) of the nose to the tragus (skin projection anterior to acoustic meatus) center of the ear |
horizontal angulation | direction of the central x-ray beam in a horizontal plane |
overlapping or cone cutting | error observed in improper horizontal angulation |
vertical angulation | direction of the central x-ray beam in an up or down position |
foreshortening or elongation | improper vertical angulation |
negative angulation | angulation achieved by positioning the PID upward |
positive angulation | angulation achieved by positioning the PID downward |
zero angulation | angulation achieved by positioning the PID parallel with the floor |
Film holding instrument | device used to place and retain the film during exposure |
Blue | anterior |
yellow | posterior |
red | bitewing |
green | endodontic |
biteblock | a device inserted between the teeth to hold the film during exposure; made of foam, wood, or plastic |
bite loop/tab | paper tab or a celluloid circle placed around periapical film, enabling the film to be used in a bitewing position |
film safe container | a lead-lined container used to hold exposed films until processing protects the film from exposure to scattered or secondary raus during exposure of films |
full mouth survey (FMX) | multiple exposures of the oral cavity showing crown and root area in a series of radiographic veiws. when arranged in mounts these films give a survey or veiw of the condition of the entire mouth |
bitewing survey (BWX) | two or four film exposures of posterior veiw to observe the crowns of maxillary and mandibular posterior teeth. anterior bitewing exposure is also possible |
edentulous survey | (without teeth) radiographic survey of a patient without teeth |
radiograph processing | is a procedure for bringing out the latent image on a film and making the exposure permanent |
developing | chemical process using the chemical elon to bring out contrast and another chemical, hydroquinone, to show contrast in films |
accelerator | solution used to swell the film emulsion during the processing |
activator | solution used to aid other chemicals in the processing activity |
replenisher solution | super-concentrated developing solution that is added to the developing tank to restore fluid levels |
underdeveloping | indufficient processing with weak chemicals or incorrect time or temperature that results in light, difficult-to-veiw films |
overdeveloping | overprocessing that results in radipgraphs that are too dark and difficult to interpret |
rinsing | water bath used to remoce chemical liquids from films during solution exchanges |
fixing | chemical process that stops the developer action and "fixes" the image, making it permanently visible |
hyposulfite or hyposulfite of sodium | chemical that removes exposed and unexposed silver grains from the film |
drying | procedure to dry films after the chemical and water baths |
safelight | special light or filtered light that can remain during the developing procedure |
duplicating radiograph | procedure utilizing a cabinet-like unit and special duplicating films to make a duplicate exposure of a processed radiograph for purposes of insureance, referral, or record |
mounting | also called carding, or radiographs is a procedure to arrange the processed radiographs in a cardboard, plastic, or stiff carrier to present a veiw of the oral cavity |
horizontal window | preset window in the mount, used to place posterior films |
vertical window | preset window in the mount, used for placement of anterior films |
bitewing window | also called interproximal window, used to place bitewing exposures |
indentification dot | preset pressed or raised area on the surface of the film |
veiwbox | a box or wall-mounted frame with fluorescent lights behind a frosted glass plate; used to veiw x-rays |
elongation | image of the tooth structure appearing longer than the actualy size; caused by insufficient verical angulation of the central ray |
foreshortening | tooth structures appearing shorter than their actual anatomical size; caused by excessive vertical angulation of the central ray |
overlapping | distortion of the film showing an overlap of the crowns of adjacent teeth superimposed on neighboring teeth |
cone cutting | improper placement of the central beam, which produces a blank area or unexposed area on the film surface caused by lack of exposure to radiation, such as when the PID is not centered properly on the film |
reticulation | crackling of film emulsion caused by wide temperature differences between processing solutions |
fog | darkening of or blemish on film that may be caused by old film, old or contaminated solutions, faulty safelight, scattered radiation, or improper storage of films |
penumbra | poor definition or fuzzy outline of forms, caused by movement |
herringbone effect | fish-bone effect on the film surface resulting from improper placement of the film |