Chapter 9: Dental Terminology all

radiant

energy that is given off from a central source

X-ray tube

also known as vacuum 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 generates the electrons

anode

positive pole; the target for the electron barrage to convert the electron force into photons

focal spot

target areas where rays are projected to make the primary beam, or central beam; the smaller focal spot produces a better image

collimator

to align; a device used to regulate the size of the beam leaving the tube in parallel rays, helping to avoid stray radiation

PID

position indicating 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 (tube wall, insulating oil, aluminum disks) devices that filter weak, longer wavelength X-rays

added filtration

filtration placed outside the tube head to meet safety standards

total filtration

the sum of the inherent and added filtration, expressed in millimeters of aluminum equivalent

milliampere control

an increase in milliamperage increases the amount of electrons available and darkens the radiograph

kilovolt power

controls the force that attracts the electrons to the anode; helps to determine the penetrating power and quality/energy of the radiation rays

exposure time

duration of the interval which current will pass through the X-ray tube; this period may be stated as fractions of a second or impulses(60 pulses to a second); the amount of exposure that a patient actually receives is measured in milliampere seconds (mAs)(mA x exposure time = mAs)

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 object to be radiographed

film speed

A (slowest) to F (fastest) speed; faster speed film requires less radiation exposure time for the patient

primary radiation

central ray of radiation emitting from the tube head and PID; primary radiation is the desired radiation and is used to expose radiographic film

secondary radiation

radiation given off from other matter that is exposed to the primary beam

scattered radiation

radiation deflected from its path during its passage through matter; may be deflected or diffused in all directions becoming weakened or another form of secondary radiation

stray radiation

also called leakage; any radiation other than the useful beam produced from the tube head; a faulty or broken tube head may be the source of the stray radiation

remnant radiation

radiation rays that reach the film target after passing through the subject part being radiographed; these rays form the latent image on the film emulsion

ion

particle that carries an electrical charge

sensitivity

ability of X-rays to penetrate and possibly ionize; the reproductive cells are more radiosensitive than the radioresistant body tissues cells; younger cells are more sensitive than older, thicker cells

cumulative effect

long term outcome of radiation; repetitive increases and intensifies the ionizing effect on cells for a buildup of damage

latent period

is the time interval between the exposure and the effect or detection

mutation effect

abnormal growth or development due to radiation causing genetic change

acute radiation exposure

radiation occurring from a massive short-term ionizing does, such as accidental exposure or explosion of radiation material

chronic radiation exposure

accumulated radiation cell damage from continual or frequent small exposures absorbed over a period of time

roentgen (R)

the basic unit of exposure to radiation; the amount of X radiation or gamma radiation needed to ionize 1cc of air at standard pressure and temperature conditions (C/kg 3880 roentgens)

rad (radiation absorbed dose)

the basic unit of absorbed radiation dose equal to 1 ergs (energy units) per gram of tissue or 1 rad= cGy

rem (roentgen equivalent measure)

the unit of ionizing radiation needed to produce the same biological effect as 1 roentgen of radiation

rbe (relative biological effectiveness)

unit of measurement used to determine amount of biological absorption effects on body tissues by different types of radiation energy

coulomb

international electromagnetic measurement abbreviated as C; 1 C per kilogram (C/kg) is equal to 3880 roentgens

maximum permissable dose (MPD)

highest rate of exposure permissable for the occupationally exposed person; the formula for calculating this factor is (5 rem per year) - (age - 18) x (5 rem per year) = MPD

erythema dose

radiation overdose that produces temporary redness of the skin

ALARA (as low as reasonably achievable)

a policy of using the lowest amount of radiation exposure possible; measures to accomplish this include proper exposure and protection aids, use of fast films, good techniques in exposure and developing, questioning the patient regarding recent exposure, and the correct calculations or control settings

dosimeter

giving measure; operator's radiation monitoring device with ionizing chamber or a device to indicate exposure and measure accumulated doses of radiation; available in the form of a film badge, pen, ring, and so on

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, shields

devices used by operators to block out scattered radiation

phantom

practice mannequin containing tooth and head structures to imitate the actual condition

DXTTR

affectionately called Dexter is a popular model

periapical film packet

size 0 (pedodontic size), 1 (adult anterior), or 2 (adult anterior and posterior); used for the intraoral periapical view of the entire tooth or teeth in a given area along with adjacent tissues and oral structures; this film may also be placed in a device or loop to expose and intraoral bitewing view and may be ordered in a double film packet if desired

bitewing film packet

(also called interproximal radiographic, size 3); film used to record crown and interproximal views of both arches while in occlusion; used intraorally with attached bite tab; other film sizes may be adapted to accomplish this task

film speeds

film are rated A to F according to the amount of exposure needed, with A needing the most time; popular trade names for Kodak film are D-ultra-speed, E-ektavision, and F-insight; other manufacturers have similar trade names for films from A to F

occlusal film packet

size 4; film that may be used intraorally or extraorally to expose large areas (2-1/4" x 3"); these film packets may contain more than one film and are marked and color-coded to identify the amount of film enclosed

extraoral films

radiographs exposed outside the oral cavity; larger in size and loaded in a film cassette or wrapped for protection from light rays

cephalostat

a device used to stabilize the patient's head in a plane parallel to the film and at right angles to the central ray of the X-ray beam; it is used for large radiographs of the head

panoramic radiograph

a special radiograph capturing a view of the entire dentition with the surrounding structures on one film; the extraoral film is placed in the machine's cassette and rotates around the patient at the same speed as the tube head rotation, providing a panoramic view; it is popular in orthodontics and oral surgery

intensifying screen

a lining of calcium tungstate phosphors or rare earth within the cassette that gives off a bluish light (calcium tungstate) or green glow (rare earth) when exposed to radiation; this combination of light and radiation forms a latent image of the film faster and reduces exposure time

CCD (charge coupled device)

is a solid-state sensor that may or may not be wired to the computer workstation; the sensor and sensor wire are barrier wrapped and inserted into a positioning device for insertion and exposure in the mouth

pixels

picture elements

PSP (photostimulatable phosphor device)

cordless, indirect sensor plate that absorbs radiation to complete a latent image; the sensor plate is placed in a barrier wrap, put in a positioning device, and then exposed using conventional exposure techniques; the plate is then processed by placing it into a scanner that will absorb the captured pixel information, compute the photon energy, and translate the image onto the screen or monitor

contrast

variations in shades from black to white; a radiograph exhibiting many variations in shades is considered to possess long-scale contrast; increased kilovoltage helps to produce this effect

density/brightness

amount of film blackening associated with the percentage of light transmitted through a film; an increase or decrease in density is accomplished by an increase or decrease in milliamperage and exposure time (mA/second)

detail

point-to-point delineation or view of tiny structures in a radiograph image; proper exposure, handling factors, and kVp selection provide good detail

definition/smoothness

outline sharpness and clarity of image exhibited on a radiograph; movement of the film, patient, or tube head is the most common cause of poor definition or fuzzy outline called penumbra

noise

high and low frequency components that hamper reception and computation of digital signals

radiolucent

describes a radiograph that appears dark, or the ability of a substance to permit passage of X-rays, thereby causing the radiographic film to darken

radiopaque

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 central X-ray beam is directly perpendicular wit an imaginary bisecting line of the angle formed by the plane of the film and the long axis of the tooth; also called short cone technique

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; also called the extension cone or right-angle technique

sagittal plane

also called midsagittal plane; imaginary vertical line bisecting the face into a right and left half; important during exposure to determine positioning of the patient

ala-tragus line

imaginary line from the ala(wing) of the nose to the tragus (skin projection anterior to acoustic meatus), center of ear; this line is important for positioning the patient in the bisecting angle technique

Frankfort plane

imaginary line from the tragus of the ear to the floor of the orbit that is used to align the maxillary arch parallel to the floor; used mostly for extraoral films; many machines that expose large extraoral films and digital images have a stabilizing chin rest or an aiming light to ensure this directional position

positive angulation

angulation achieved by positioning the PID downward; also called plus angulation; maxillary exposure are incisors (+40 degrees) cuspids (+45 degrees) bicuspids/premolars (+30 degrees) and molars (+20 degrees)

negative angulation

angulation by positioning the PID upward; also called minus angulation; mandibular exposures are incisors (-15 degrees) cuspids (-20 degrees) bicuspids/premolars (-10 degrees) and molars (-5 degrees)

zero angulation

angulation achieved by PID placement parallel to the floor

horizontal angulation

direction of the central X-ray beam in a horizontal plane(side to side) ; the central beam must be placed perpendicular to the film front and teeth alignment; the error observed with improper horizontal angulation is called overlapping or cone cutting

vertical angulation

direction of the central X-ray beam in an up or down position; improper vertical angulation results from foreshortening or elongation errors

PID

position indicating device, formerly called a cone; may be a long cone (12-16 inches) or a short cone (8 inches); may be round or rectangular, open-ended tube; it is used to collimate and direct the central beam, and it also determines the target-surface distance

film-holding instrument

device used to place and retain the film or sensor in the oral cavity during exposure; are color coded to designate area placement

-blue: anterior placement

-yellow: posterior placement

-red: bitewing placement

-green: endodontic placement

biteblock

device inserted between the teeth to hold the film during exposure; made of foam, wood, or plastic

individual film holder

a grip device, such as Rinn's Eezee-grip, that will hold one film or one sensor for exposure in the mouth; mostly used in a small mouth or difficult areas, the loaded film holder is put into position and held by the patient's bite or finger pressure

bite loop/tab

paper tab or celluloid circle placed around periapical film, enabling the film to be used in a bitewing position; this combination is used in place of a commercially manufactured interproximal film; some bite loops are constructed to assist with stabilizing and holding the digital sensors in the film holding device

film-safe container

a lead-lined container used to hold exposed films until processing; protects the film from exposure to scattered or secondary rays during exposure of films

full mouth survey (FMS or FMX)

multiple exposures of the oral cavity showing crown and root area in a series of radiographic views; when arranged in proper sequence, these films or images give a survey or view of the condition of the entire mouth

bitewing survey (BWS or BWX)

two or four film exposures of the posterior view to observe the crowns of maxillary and mandibular posterior teeth; anterior bitewing exposure is also possible

endentulous survey

radiographic survey of a patient without teeth

radiograph processing

procedure for bringing out the latent image on a film and making the exposure permanent; the procedure involves developing, rinsing, fixing, washing, and drying; processing may be completed in an automatic film processor or by manual methods in a processing tank

developing

chemical process using the chemical elon to bring out contrast and another chemical, hydroquinone, to show contrast in films; developing brings out the latent image on the film's silver halines that were affected or darkened by radiation

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

rinsing

water bath used to remove 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 on 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 insurance, referral, or records

magnification

also called the "zoom in" property; machine ability to enlarge selected pixels to produce a larger more visible viewing area

color substitution

pseudocolor enhancement; more appealing to patient; machine process of substituting a selected color shade for specific digital shade numbers to produce a color screen image

digital substitution

technique used to determine small changes in image sequences; use of before treatment and after treatment image comparisons may not be evident to the human eye but can be mathematically compared and evaluated

teleradiography

ability to transfer the captured information to other sites and sources by the computer DICOM interchange (digital imaging and communication in medicine)

mounting

also called carding of radiographs is a procedure to arrange the processed radiographs in a cardboard, plastic or stiff carrier to present a view of the oral cavity

horizontal window

preset window in the mount that is used to place posterior films

vertical window

preset window in the mount that is used for placement of anterior films

bitewing window

also called interproximal window; used to place bitewing exposures