Lecture 6 Radio

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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

Lecture 6 Radio

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