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Lecture 6 10-March-2013
Dental X-ray Film-The exam will be 40 Q and the time will be 30 mins.
-8 chapters are going to be included in the exam so 5 Qs will be on each chapter, unless
the chapter is not from the book.
-no need to study the 1st
chapter from the book which was talking about names, however
the Dr lecture was important, so the names are not important.
-everything that the Dr said during the lectures is included in the exam, even if it's not
mentioned in the book.
So the last time we talked about the measures of protection, and
how to protect yourself and the patient, and as a worker in radiography I
need to measure the amount of exposure that is coming to me (not to the
patient) and we can measure this amount be using the badge, TLD or other
things, the badge is a kind of film, it will be processed like a film, and it will
be permanent record, however the TLD will be erased, so it's not permanent,
TLD is lithium florid, this material will absorb X-ray and then we put heat
on it and the light will come, so it's phosphorus material, then we can
measure the amount of X-ray.
So if you opened a clinic, is it necessary for you to have a TLD or
film badge? The Dr didn't answer; I think the answer is in the previous
script.
So let's start our main topic in this lecture, 1st
of all what could you find
inside X-ray film? What is the composition of X-ray film? How to protect
your films? What do we mean by fogged films?
When you open the film bag you'll find the film itself, in addition to lead
foil, and a black paper surrounding the film, now let us see the composition
of the film itself.
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Film comp
If you have a cross secti
you'll see the component
1- The base.2- Adherent (Adhesive l3- The emulsion, which
halide crystals with g
4- The protective layer.
Film base is fixable piecslight blue tint to reduce
give strength. So if you dfilm it will be slightly bl
We need the adhesive lthe base before emulsio
Emulsion is the main cit's mixture ofgelatin a
halogen like iodide and
will absorb the radiatio
image that you cannot s
and we need gelatin to
processing solution andcrystals during film pro
Finally we have the proprotect emulsion from
So you can see these co
osition
n of the film
s, so you have:
yer).
means silver
latin.
of polyester plastic; it's transparent a
the eye pain. Its primary purpose is to
idn't make exposure to the film, and pe because of the base.
yer to stick the crystals to the base, sois applied.
mponent of the film, it's sensitive to r
d silver halide crystals, halide mean
bromide, it depends on the type of the
and result in latent image (latent ima
ee unless you process the film, it's like
uspend millions of halides crystals, it
allows the chemicals to react with theessing.
ective layer; it will cover the emulsio
echanical and processing damage.
ponents using the microscope.
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d exhibits a
support and
ocess the
it's added to
adiation, and
s sliver plus
film, and it
e means
magic ink),
absorbs the
silver halide
, and it will
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Type of X-ray films
We have 3 types of X-ray films:1- Intraoral films.2- Extraoral films.3- Duplicating films: in the past we had machines for film duplication,
maybe they are not available now, we need to duplicate films to give one
films to the patient and the other will be kept in the clinic as a record, orfor insurance issues for example, now we use a type of packets that
contains two films, so we can process two films instead of one.
Intra oral films
Intraoral films are defined as films that we put inside the mouth of
the patient during exposure, and they are used to examine the teeth and
there supporting structures, so it's small film so it can be used inside the
mouth, however occlusal films are intraoral but they are large.
Intraoral film packaging > Intraoral films are found inside a tightly sailed
packet, to protect it from light and saliva (sometime when we say packet
we mean film, so these terms are
interchangeable).
So when you open the packet you find the film
which is the green one, and you find the paper
(film rubber) which is the black one, you'll find alsothe lead foil and the packet. (look at the picture to
the right)
In the dark room when you process the film, you won't see the film inside
the processor machine, however sometimes you can see it if the machine
has a window, otherwise you will open the packet and feel where is the
film.
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The film usually comes with a dot, and this
dot will help me in mounting the film, in order
to differentiate between the right and the left
of the film (or the patient), and when we do
periapical film (which means films in which
we need to see the apex) we need to put the
dot occlusally, it's not good to see the dot on
the apex, so the dot must be far from the
apex if it's periapical film.
So the dot actually is convexity, and when you mount the film thisconvexity must be toward you, so the fixed thing when you take you film
from the processing machine is to put the film in a way so that the
convexity of the dot will face you.
X-ray film is usually a double emulsion film, what is the difference
between single emulsion and double emulsion? Please search about it.
{{Single emulsion film: emulsion is coated on only one side of the film; film
is viewed from emulsion side only.
Double emulsion film: emulsion is coated on both sides, and the film can
be viewed from earthier side, this type of film requires less exposure
compared to single emulsion.}}
We have also the black paper that cover the film and protect it fromaccidental exposure to light, and you know that films are sensitive to light
even after the exposure to X-ray, because not all the silver crystals will be
ionized from the first time, so if it's exposed to light your film will be hazy
)( .
Lead foil (or the sheet), lead prevent X-ray from passing through it, so its
function is to absorb the scattered radiation preventing them from
reaching the film, so it will reduce secondary X-ray.
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So if you accidently put the back of the film toward the tube, and you did
your exposure, your film will be light, and you'll find the pattern of lead foil
on the film, sometimes you'll have ?hearing bone? (Fish skeleton) or tire
trace, raised diamond pattern, so one of the causes of white film after
processing is to expose the back of the film. The lead foil prevents
improper film exposure to the X-ray.
The Dr said that there is some Dr whose name is James in the university of
Ohio who prepared an excellent slides for the basics of radiology.
As we said the outer package wrapping is made of plastic and it's there to
protect the film from saliva and light, it has two sides; the tube side and
the label side, the tube side is white solid and has the convexity of the dot,
it's not smooth so we'll avoid slipping, the other side (label side) which has
two colors must be away from the tube, it's color coded, so you'll find the
white color and another color to distinguish between one film and two
films.
So on label side which is not toward the tube (the pic next
page) we can see:
1. a circle which tells us about the place of the dot,2.statement (opposite side toward the tube),3. The manufacturer name (Kodak),4. The speed of the film, the size of film (we use 1 for kids
and 2 for adults).
5. The color would be different among one film packet and
two film packet, also would differ among different speeds
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(the color coding is not for memorizing).
Barrier packets (the pic below) are a way by which we can protect the film
from contamination (cross infection control measures), so when we open it
the film would be dropped into a cup for example and then we can take
the gloves off, because our hands will be clean and the film will be clean.
Usually films will not come as a single film, it will come into boxes which
contains 100 films or 150 or whatever.
Films of a near expiry date are usually cheap and that because thesefilms won't have good resolution, so film will be usually foggy )( .
Intraoral film types
Intraoral film could be periapical film or occlusal film or bitewing film, in
bitewing the patient will bite on a wing of the film (which comes already
with the film or could be self made), so in old days the Drs were not using
holders, it was easier for them to stick anything to the film so it will
become a wing on which the patient bite, but nowadays holders areavailable.
Bitewing film (the pics below) would touch the lingual surface of bothmaxillary and mandibular teeth, so it will show me maxillary and
mandibular teeth and occlusal plane would be in the middle of the film,
it's the best for detecting interdental bone loss and caries, we can use the
bite wing instead of holder when the patient cannot tolerate the holder
because it's bulky, or when the patient have gagging or he is not
cooperative.
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periapical film (the pic below) by which we can see the apex and theperiapical tissue (at least 2 mm), it would be parallel to the lingual side
of teeth, if it's anterior teeth we would put the film vertically, if it's
posterior teeth we would put it horizontally, from its name it's good todetect the periapical lesion.
We have occlusal films (the pics next page), are large film of size 4, sothey are the largest intraoral films, the aim is to show us wider area, and
to show us the bucco-lingual dimension, the solid surface of the film
must be toward the cone and the arch that we are going to take X-ray for
it, in case of the mandible we ask the patient to tilt his head 45 degree or
90 degree depending on the technique.
Intraoral film sizes
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The sizes of the films depends on its
type, for periapical films we have sizes 0,
1, 2, for bitewing we have 0,1,2,3, and
for occlusal we have only size 4, the size
we chose depends on patient as we said
we use 0, 1 for kids and 2 for adults, or it
depends on the technique for example
sometimes we use size 1 if it's anterior
teeth of adult.
Intraoral film speed
The speed (sensitivity of the film) is the amount of radiation that is
required to produce radiograph of standard density.
The speed depends on :
1. the size of silver halide crystals, So when we increase the size of
crystals the speed will be increased (but this will decrease the details or the
resolution),
2. The thickness of emulsion, the speed will be coded from A to F, F is the
highest speed, D speed is called ultra speed, E speed is called ectaspeed,
and F speed is called insight.
E speed needs 50% less exposure than D, and F speed needs 20% less
exposure than E, F is considered the safest because the dose of X-ray to
patient will be the least.
Why F is faster than D and E?
We have 2 types of crystals, we have tabular crystals and we have globularcrystals, when the crystal is tabular it means wider area would be toward
the X-ray, so this will increase the speed.
A, B, C are not allowed to be used because of less safety, while D, E, F can
be used.
3. Presence of special radiosensitive dyes.
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Extraoral films
Extraoral films are films that would be outside the mouth, the most famous
type of it ispanoramic film which shows both maxilla and mandible and
maxillary sinus, so the types of extraoral films are:
1- Panoramic films.2- Lateral cephalometric film.3- Lateral oblique.4- Posterior-anterior radiograph.5- Water's view.(There are more types than this)
extra oral films could be screening
films (or intensifying screens) and
non-screening films, non screening
films are not used in dentistry,
screening films contain phosphorous
material, which will change X-ray into
light (green or blue depending on the
type of material), so we can use less dose, so because the image is fromoutside this means that the X-ray will pass through many important
structures so the idea was to use screening to reduce the dose.
So it is cassette, inside the cassette will be 2 screens, and between them
we have the film, the front screen is plastic, and the back screen is metal,
the front screen should be toward the tube.
The films we use with screens have to be sensitive to specific colors like
blue or green and its sensitivity must be compatible with the sensitivity of
the screen. Blue light sensitive is called (Kodak X-Omat and Ektamat),
where as others are sensitive to green light is called (Kodak ortho and T-
mat films)
The packet contain label with the type of film, silver size, the total number
of films and radiation.
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In terms of sizes we hav
used in panoramic radio
longest.
Usually when we put the
room because films are
So these are pics of pan
5X7 is used for bilateral
Nowadays we mainly us
The use of intensifyin
the resolution will be les
better with screen.
We have conventional c
and we have rare earth (
example!
We have what i
produced by crystals spr
on both sides, so the sha
8X10 in, 5X7, 5X12, and 6X12, all of t
raph, horizontally; panoramic radiog
film inside the cassette we put it insi
ensitive to light.
ramic film (the left) and cephalometri
MJ and 10X10 is used for cephalomet
8X10 for cephalometry, and tomogr
screen will decrease the sharpness o
s than direct film; however contrast r
lcium tungstate screens which emits
phosphor) screens which emit green l
called T-mat crossover, in which the
ad out and goes to the film and affec
rpness of image will decrease.
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hese are
aph are the
e the dark
c film:
ry.
m.
the film, so
solution is
blue light,
light for
light
emulsion
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And we have something called anti-crossover called Etavision, here we
have crossover control layer before the emulsion, so it will be: the base,
control layer, emulsion, coating and screen support so there won't be
crossover.
Intensifying screen could be classified according to fastness to: fast,
medium and slow.
Cassette are needed to hold the screens, they are available in varying sizes,
and could be rigid or flexible, but usually we use flexible.
In the past they were using cassettes also for occlusal, because we had a
technique in which the x-ray is going through the brain, nowadays it's
abundant, so no need to use cassettes anymore.
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Cassette holder must be light tight ) ( to protect the film.
We must have good contact between the film and screen, not to use image
intense; Lack of contact between screen and film results in a loss of image
sharpness.
We have something called cassette bagging, and also we have R and L
which means right and left sides.
Anything between the film and the cassette will result in white spot after
processing sometimes we have these white spots, when you see it then
you'll think that this is calcification, but remember to chick your cassette
first is it clean or not.
Duplicating films
Let's talk about duplication films, usually we use duplicating machine in
dark room, and it's covered by emulsion on one side, so duplicating film is
kind of film on which the emulsion is on one side, so we put the emulsion
side on the top of the film which we need to duplicate and we use the lightto duplicate it, when the film is more opaque it means more exposure, so
it's not like normal X-ray.
Storage
film is adversely affected by heat, humidity and radiation.
Films are sensitive to light, so X-ray films must be store in cold weather
(5070 degrees F)so not necessarily in the fridge, and must be awayfrom humidity (must be 30%- 50%),however in winter (low humiditycircumstances) we need to increase the humidity in order to prevent
fogging and electrostatic effect, and the film must also be stored away
from chemicals and sources of radiations.
It's better to use lead lined storage area, dispenser can be used, and extra
oral films should be stored standing (parallel to each other) to prevent
damage .
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Ideally films should be stored:In a refrigerator in cool, dry conditions
Away from all sources of ionizing radiation
Away from chemical fumes including mercury and mercury-containingcompounds
With boxes placed on their edges, to prevent pressure artefacts.
Use film before expiration date to avoid film fogging.
Types of film holders
Styrofoam bite block, examples include XCP bite block and stable bite-block Molded-plastic devices example the Snap-A-Ray Other film holding include EndoRay and Uni-bite devices
Types of Beam Alignment Devices
Examples the XCP and BAI beam alignment devices
For the last two outlines the Dr mentioned the examples only, please go back to chapter
6 in the book for more details.
Sry for that low quality script, but I have my own circumstances that
obligated me to do it that way, and the Dr way of talking and voice were
not that clear.
Done by: Ammar Aldawoodyeh
Checked by Sawsan Jwaied