Dental Radiology - Xray films (2) Flashcards
what are the 4 components of a traditional xray film
film base, adhesive layer, film emulsion and protective layer
Film base is made of a thin plastic (0.2mm) and is made to withstand what conditions
heat, moisture and chemical exposure
the adhesive layer attaches emulsion to film base and is located where
on both sides of the base
what is film emulsion made of
silver halide crystals and gelatin
what is the purpose of silver halide crystals in film emulsion
to give it sensitivity to radiation in order to produce an image
the protective layer is a thin transparent coating that protects from
physical manipulation and chemical processing
what is the purpose of gelatin in film emulsion
to suspend and evenly dispute crystals over the film base
what material absorbs processing solution to allow for chemicals to react with halide crystals
gelatin
A chemical compound sensitive to light and radiation is known as
silver halide crystals
Silver halide crystals are composed of
silver and a halogen (bromide or Iodide)
what’s the percentage of silver bromide crystals in emulsion
80-99%
what’s the percentage of silver iodide crystals in emulsion
1-10%
How is a latent image created by halide crystals
the silver halide crystals absorb the radiation during exposure and store the energy from it. A pattern is then created by the stored energy
Latent image
a image created by a pattern in the crystals that comes from stored energy
an image that is existing but not yet developed is known as a
latent image
Masking of a image prevents
crystals underneath the cover from being exposed to radiation
what is the process chain of silver halide crystals
exposure> Processing > Visible/stable image
What are the 3 types of xray film
intraoral, extra oral, duplicating film
Intra oral film is placed where
inside the mouth
Outer waterproof wrap, black paper wrapper, film, lead foil are all components of
traditional intra oral film
what is the purpose of lead foil
to shield film from secondary radiation
what is the purpose of a black paper wrapper
to shield film from light
The identification dot (A) is used to
identify between right and left sides when mounting
lead foil is considered __ and is ___
hazardous waste, properly disposed of
Size 0 film is used only for
small children PA and BW’s
Size 1 film is used for __ with the paralleling technique
adult anterior PA’s
Which film size is considered standard film?
size 2
size 2 film is used on adults for
posterior PA’s and BW’s and anterior PA’s with bisecting technique
can you use size 2 film on a child with a large mouth or for child occlusal films
yes
what is size 3 used for exclusively
extra long adult posterior bite wings
a size 3 film will cover __
one entire side of the mouth (max and mand)
what Is size 4 film used for
adult occlusal films
the mandible can continue growth until what age
20’s
what is a prominent feature of maxillary occlusal films
the midsagital suture line
Periapical films are used to examine
the entire tooth, crown, root, and surrounding bone
Periapical also means
around - apex
root margins, infection/disease, decay and bone health are all aspects that a ___ film would show
periapicial
What sizes of film are used for PA’s
0,1,2
3 types of intraoral film
Periapical, bitewings, and occlusal
what size film is used for PA anterior on an adult using the paralleling technique
size 1
what size film is used for PA bisecting adult anteriors and posterior
size 2
a size 0 film is used for PAs on
children
Bitewings are used to examine
crowns of max and mand, interproximal
overhangs, calculus, caries, height of crestal bone are all shown on what type of film
bitewings
what is a bitewing series
2-4 films of posterior teeth to detect and document internal structure of tooth
what is the minimum set of xrays you’d receive at a hygiene check up if any
bitewing series
sizes used for bitewings are
0, 1, 2, 3
occlusal films are used to
examine the maxilla and mandible
what sizes are used for occlusal films
size 4, and 2
the amount of radiation needed to produce a radiograph in relation to film is known as
film speed
film speed is determined by
the size of sliver halide crystal, thickness of emulsion and presence of radiosensitive dyes
the larger the halide crystal, the ___
faster the film speed
a faster film results in an image that is
less sharp
which film speed is the fastest
F speed
the speed requiring a 60% decrease in exposure from D speed film is
F speed
2 types of extra oral films
panoramic, cephalometric
extra oral films are used to examine
large areas of skull and jaw
when prepping a patient for a panoramic you would
explain the procedure, place double sided lead apron, and remove any object on the head that could compromise the quality of scan
How would you position a patient for a pan
spine straight, teeth on groove, midsagittal perpendicular to floor, Frankfort parallel to floor, lips around block, and tongue on roof of mouth
the midsagittal plane is
down the midline of face
the frankfort plane is
top of ear through to bottom of the eye and across
Cephalometric film is used to measure the
growth and development of the skull
2 types of extra oral films
screen films, nonscreen films
screen films are used with ___ to reduce radiation to pt
intensifying screens
nonscreen films are not recommended for dental radiography because they
require more exposure time
what are the two components of screen films
cassettes and intensifying screens
cassettes keep the light out so that the intensifying screen can
transfer energy to light and expose it to screen film
intensifying screens are made of
smooth plastic coated in small fluorescent crystals
fluorescent crystals are AKA
phorphors
fluorescence emit what color light
blue and green
Conventional calcium tungstate screen emits a
blue light
newer rare earth screens emit a
green light
which color emitted from the intensifying screens are more effective and require less radiation
green light
What is duplicating film
making a duplicate of a copy to send for insurance companies and specialists
duplicating film only has one side of
emulsion
is duplicating film exposed to xrays
no, made in dark room using a Lightbox
a double film packets creates
2 identical images from one dose of radiation
what is the ideal temp for film storage
50-70F or 10-21C
ideal humidity for film storage
30-50%
do films have an expiration date
yes, first in first out
what type of container is film store in
a lead lined/radiation resistant container to prevent film fog
what is film fog
caused by scatter radiation, it attaches to film making later exposure not stick
do edentulous patients need radiographs
yes
Radiolucent structures appear
dark or black, radiation passes through
radiopaque structures appear
light and white, radiation can’t pass
enamel, bone, restorations are examples of
radiopaque structures
air, access, pulp are examples of
radiolucent
contrast is
degrees of blackness / shade of greys
low contrast images show _
lots of grey shades
high contrast images only show
black and white
which electrical factor has influence on contrast
Kvp
a low kip results in less adequate waves, meaning a ___ contrast
higher
long scale contrast is aka
low contrast
short scale contrast is aka
high contrast
the step wedge is a form of quality assurance that demonstrates
contrast scales produced by exposure
density is the overall
blackness of an image
what settings would give you a full range of grey shades
properly balanced kvp and ma
3 geometric influences
sharpness, magnification, distortion
what 3 things influence sharpness of an image
size of focal spot on target, size of halide crystals, movement
if you increase the length of your PID, the magnification of the image would ___
decrease
if the distance from the object being examined to the receptor is increased the magnification would also
increase
distortion is the
variation in size and shape from true form
if a receptor is placed to far or with an insufficient angle the image would be
distorted
quality + quantity =
intensity
inverse square law states that
the intensity of radiation is inversely proportional to the square of the distance from radiation source
inversely proportional means that when one variable increases, the other
decreases
if you changed a 8” PID out for a 16” PID the intensity would ___
be 1/4 as intense
changing from a 16” PID to an 8” PID would change the intensity to
4x as strong
