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Science
Medicine
Radiology
dental careers final (ch 38 & 39)
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Terms in this set (96)
the uses of dental images include the detection of
bone loss in its early stages
exposure to radiation:
no matter how small, has the potential to cause harmful biologic changes
the x-ray was discovered on November 8, 1895, by
Wilhelm Conrad Roentgen
the dentist who is credited with the first practical use of radiographs in dentistry in 1896 is
Edmund Kells
anything that occupies space and has form or shape
matter
structure of the atom
the orbital path of an electron around the nucleus is called an electron shell
in dentistry, the ______ wavelengths of the x-rays, the greater their energy and usefulness
shorter
which component of the x-ray machine functions in positioning the tubehead?
extension arm
the heart of the x-ray generating system is the
X-ray tube
secondary radiation
refers to x-radiation that is created when the primary beam interacts with matter
which of the following structures will appear radiopaque on dental x-ray film
metal restorations
term used to describe areas that appear dark on the image
radiolucent
term used to describe areas that appear white or light gray
radiopaque
the range of shades of gray between black and white on an image is called
contrast
the degree of density or blackness on an image is controlled by the
milliampere seconds
______ will improve the sharpness of a radiographic image
smaller film crystal size
damage caused by ionizing x-radiation to genetic cells
can affect future generations
which of the following tissues has the highest radiation sensitivity
small lymphocytes
a lead apron and a thyroid collar
must be used on all patients for all exposures
the guidelines for prescribing dental radiographs issued by the American dental association and the FDA recommend which of the following dental imaging procedures for a pregnant patient
radiographic imaging procedures do not need to be altered
one of the rules of radiation protection is to never stand closer than _____ feet from the x-ray unit during an exposure unless you are behind a barrier
6
dental imaging
-refers to film based images
-refers to digitally produced images
-detects conditions that might otherwise remain undetected
electromagnetic radiation
-are made up of photons that travel through space in waveforms
-they differ only by their wavelengths
they travel in straight lines
a _______ is a minute bundle of energy that has no weight or mass
photon
the _____ is the portion of the x-ray machine which supplies the electrons to produce x-rays?
cathode
if you change the exposure time of the x-ray unit. what is affected?
number of x-rays produced
the _______ setting controls the penetrating power of the x-ray beam
kilovolt
a step down transformer is necessary within the x-ray circuitry to
boil off electrons from the filament
heat is reduced from the target by
-insulating oil
-copper stem
thermionic emission refers to the
release of electrons from the tungsten filament
the lead collimator is used to ______ of the primary beam
restrict the size and shape
how much filtration is federally required for a dental x-ray machine operating over 70 kVp?
2.50mm
filtration is used to
remove long wavelengths from the beam
filtration are discs made of
aluminum
primary radiation is
-also called the useful beam
-the beam of x-rays that comes from the target
the fuzzy or blurred area around an image is called the ______
penumbra
a penumbra in a radiograph can be reduced by
limiting movement
which council determines the radiation effects and levels tolerable for humans
national council on radiation protection and measurements
because the entire x-ray is considered a radiation hazard area, a radiation hazard sign must be posted in
-sight of patients
-sight of personnel
the time lapse from x-ray exposure until noticeable damage occurs is known as
latent period
chronic radiation exposure occurs when _____ doses of radiation is received over a _____ time period
small; long
damage to which type of cell is passed on to future generations
genetic cell
which organ isn't as sensitive therefore not considered a critical organ
muscles
the maximum permissible dose for an occupational worker for an individual 18yr old or older is ____ rems per year
5
film badges
-should be worn at work only
-badge is usually worn for 3-4 weeks before returning it for reading
-if an assistant follows all safety precautions, exposure should be near zero
who should hold the film in a patients mouth if the patient is unable to do so
parent/relative of patient
a patient is concerned with radiation exposure. you can assure him that your office utilizes the ALARA concept which is
-reducing the number of exposures
-minimizing retakes
-keeping exposure levels as low as possible
one of the earliest signs of overexposure to x-rays may be
erythema
if the operators film badge indicates an exposure to small amounts of radiation, what should be done
evaluate the x-ray equipment and techniques
if a patient is small and petite, to get the same density radiograph it is best to reduce the
exposure time & mA
example of cumulative radiation exposure
-cataracts
-leukemia
-cancer
the dentist says that the image has too much contrast; he would like to see more grays. what adjustment would you make
increase kVp
when in storage, the lead apron should be
hung or draped over a bar
a good technique for reducing the radiation exposure to both the patient and the operator is the use of
fast film or digital imaging
a radiograph that has an overall gray appearance is generally preferred. this x-ray is said to have
low contrast
how well the image reproduces fine detail or distinct outlines of an object is called
sharpness
the location where x-rays are produced in the X-ray tube is called the
focal spot
when the electrons slam again the target, _____ are generated
99% heat, 1% x-rays
when the exposure button is engaged, what happens?
-the high-voltage circuit is activated
-kilovolts drive the electrons to the target
-electrons slam against the target producing the x-ray
an exposure time of 1/2 second is equal to _____ impulses
30
when the master switch is on
the electron cloud is emitted
dental film holders, used to position and hold the dental x-ray oil in the patients mouth
PID & XCP/disposable block
the radiographic image is located within the ____ of the radiographic film
gelatin that suspends the emulsion
_____ -speed film is the newest and fastest film currently available
F
the most commonly used film size for adult intraoral dentistry is size
#2
an extraoral film that is placed outside the mouth during x-ray exposure
panoramic
a film cassette made of plastic or metal is used to hold and protect the extra oral film. during exposure, the _____ side of the cassette must always face the patient
front
an _____ is a device that intensifies or increases the effect of the radiation and decreases the amount of exposure time needed when exposing an extra oral radiograph
intensifying screen
_____ hardens the film emulsion during film processing
fixing
automatic film processing requires ____ than manual film processing
less equipment
what time and temperature errors will result in reticulation of the film emulsion
sudden temperature change between developer and water bath
developer cutoff will result in a _____ border
straight white
the CCD found in direct digital imaging sensors is made of
silicon
which category of digital imaging is similar to faxes and video equipment, which use sensor with a cord that is attached to the computer
direct digital radiography
storage plates used with (PSP)
-they're made of phosphor
-the latent image will stay on the plate for hours
-they should not be exposed to light before scanning
image plates
-they need to be protected in the patients mouth with barriers
-pthey require care not to scratch when handling
-they are positioned in the mouth like dental film
positioning instruments in digital radiography
-assist in film placement
-keep the patients fingers from being exposed
film speed is determined by the
size of the silver halide crystals
the purpose of the lead oil in the dental film packet is to
reduce film fogging
when placing a dental film int he patients mouth, the white side is placed _____ the tube and the raised dot to the _____
toward; occlusal or incisal
duplicating films emulsion
-it is only on one side
-it appears dull
-it is exposed by light
the _____ is the safest place to store unopened boxes of dental film
darkroom
correct order of steps in manual film processing
develop, rinse, fix, wash
solutions should have been changed in the processor one week ago. continuing to use exhausted developer will result in ____ films
dark
the recommended distance between the safelight and where the films are unwrapped is
4 feet
what will affect the life of the processing solutions
-number of films processed
-size of films processed
-time elapsed since last change
the gallon of fixer is mistaken for developer, and developer is mistakenly thought to be fixer. as a result, films pass though the fixer first, then the developer. each film will now be
clear
the film is lighter than normal; what is the probable cause?
the developer solution is too weak
in the automatic processor, the developing solution is normally 81-83 degrees. if it gets hotter how will the films look?
dark or black
the ideal time and temperature for manual developing is
5 mins at 68 degrees
what is the cause of white spots on a processed film?
fixer contacts film prior to processing
when loading the film into the cassette before exposure (extra oral radiography), the
procedure must be done in the darkroom
a _____ image is produced when x-rays interact with the film emulsion
latent
extraoral film is
just as sensitive to light as intraoral film
digital radiography requires less radiation than traditional radiography because the
sensor is more sensitive to x-ray energy
digitizing film-based radiographs
-the process is similar to other film duplication
-desktop scanners capture the light signal
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