week 9

chapters 9 and 10

what are the four dental x-ray film basic components?

==film base==

==adhesive layer==

==film emulsion==

==protective layer==

film base

* a flexible piece of polyester plastic that is constructed to withstand heat, moisture, and chemical exposure
* it is transparent and exhibits a **slight blue tint** that is used to emphasize contrast and enhance image quality

adhesive layer

thin layer of adhesive material that covers __**both**__ sides of the film. it is added to the film base before the emulsion is applied and serves to attach the emulsion to the base

\

film emulsion

this coating is attached to both sides of the film base by the adhesive layer to give the film greater sensitivity to x radiation.

the emulsion is a homogeneous mixture of _____ and _____________________

gelatin, silver halide crystals

used to suspend and evenly disperse millions of microscopic silver halide crystals over the film base

==gelatin==

==halide crystals==

a chemical compound that is sensitive to radiation or light

What are the the two types of silver halide crystals found in the film emulsion?

silver bromide( 80-99% used) and silver iodide

protective layer

thin coating over the emulsion to protect the emulsion from damage such as mechanical and processing damage

the pattern of stored energy on the exposed film cannot be seen and is referred to as a

**latent image**

When does the latent image become a visible image?

when it undergoes chemical processing procedures

The silver bromide crystals exposed to x-ray photons are ______ , and the silver and bromine atoms are separated

ionized

Irregularities in the lattice structure of the exposed crystal, known as sensitivity specks, attact the silver atoms. these aggregates of neutral silver atoms are known as ___________________

==latent image centers==

What are three types of x-ray film that may be used in dentistry?

* intraoral film
* extraoral film
* duplicating film

This type of film is placed inside the mouth to examine teeth and supporting structures

intraoral film

What is intraoral film packaging used for?

==used to protect the film from light and moisture==

4 components of a film packet

* x-ray film
* paper film wrapper
* lead foil sheet
* outer package wrapping

Is the intraoral x ray film double emulsed or emulsed on one side? WHY?

the intraoral x-ray film is a double-emulsion film (on both sides). This is used because it requires less radiation exposure to produce an image

What are two film packets used for?

They produce two identical images with the same amount of exposure and used when a duplicate record of a radiographic exam is needed

==What is used to determine film orientation?==

identification dot

paper film wrapper

black protective sheet used to cover the film and ==protect it from light==

What is located behind the film wrapped in protective paper?

lead foil sheet

lead foil sheet

* shields the film from back scattered (secondary) radiation that creates film fog
* has a herringbone pattern that is visible on a reversed film

What are the two sides of outer package wrapping?

* tube side
* label side

soft vinyl or paper to seal the contents and protect them from light or moisture

outer package wrapping

tube side

soild white and has a raised bump in one corner that corresponds to the ID dot

* ==this side should face the tubehead during an exposure==

Label side

color coded to identify bw one and two film packs and according to film speed

* ==has a flap used to open the film packet before processing==

TU**B**E SIDE is a solid white

Dot is a **b**ump

**LA**BEL SIDE has color

dot is f**la**t

what are three types of intraoral film types?

* periapical
* bite-wing
* occlusal film

PA film sizes and what are used for

* size 0 PA film used for very small children
* size 1 PA film used primary to examine anterior teeth in adults, but also adults
* size 2 PA film (standard film) used to examine ant and pos teeth in adults

BW film sizes and uses

* size 0 bw used to examine pos teeth in small children
* size 2 bw used pos teeth in older children and adults
* size 3 shows all posterior teeth on one side of arch in one rad
* ==currently not recommended because all the contact cannot be opened in one film==

occlusal film sizes and uses

* size 4 is used to show large areas of the maxilla or the mandible

==A size 4 film is almost _____ times as large as a standard size 2 film==

4

film speed

amount of radiation req to produce a radiograph of standard density

what is film speed, or sensitivity, determined by?

* ==size of the silver halide crystals==
* ==thickness of the emulsion==
* ==presence of special radiosensitive dyes==

**a fast film requires ________ radiation exposure**

less

**_ speed is the fastest film used in dentistry today**

F

the _____ the crystals, the faster the film

\
larger or smaller?

larger

A(slowest)-F(fastest) speed, what film speeds are used for intra oral radiography?

==D- speed==

==E-speed==

==E/F-speed==

==F-speed==

F-speed films reduce radiation dose to the pt but also provide _______ contrast characteristics under various processing conditins

stable

How much more faster is F than D? and what makes it faster?

* The f- speed film requires 60% of the exposure time of the D-speed film.


* the larger crystals and the increased amount of silver bromide in the emulsion make it faster

placed **outside** the mouth during an exposure and ==used to examine large areas of teeth and jaws==

extra oral film

Two types of extraoral fiml

* panoramic film
* cephalometirc film
* bony and soft tissue areas in profile (from the side)

T/F

extraoral film packaging is enclosed in moisture-proof packs

False

extraoral film types

* screen film
* nonscreen film

screen film

==requires the use of a screen in a cassette with phosphors for exposure==

**The screen film is sensitive to _______ light, rather than direct exposure to x-radiation**

fluorescent

**Some screens are sensitive to blue light or green light**

* blue sensitive film must be paired with screens that produce blue light
* green sensitive film must be paired with screens that produce green light

This type of film is **not recommended for dental use** and does not require a screen. ==It is exposed directly to the x-rays==

nonscreen film

in EO radiography, screen films are used in combo with two special equipment items

* intensifying screens
* cassettes

intensifying screen

transfers xray energy into visible light, the visible light, in turn, exposes the screen film

with the use of __________, less radiation is required to expose a screen film, and the patient is exposed to less radiation

intensifying screen

In EO radiography, a screen film is _______ between two intensifying screens and is secured in a cassette

sandwiched

==an intensifying screen is a smooth plastic sheet coated with minute fluorescent crystals called==

**phosphors**

When the phosphors are exposed to the xrays, they emit visible light in the blue or green spectrum which then exposes the film. What are the two types of screens?

* calcium tungstate
* rare earth screens

calcium tungstate screen

have phosphors that emit **blue light**

rare earth screen

have phosphors that emit **green light**

* ==these req less radiation than calcium tungstate screens==

cassette

**used to hold the film and the intensifying screens**

==cassettes may be flexible or rigid. most are ______==

rigid, bc lasts longer and better protects screens from damage

both rigid and flexible cassettes must be light tight

==the lack of contact btw film and cassette will result in a lack of sharpness of the image in that area==

a rigid cassette has a front cover and a back cover.

* the front cover faces the ________ and constructed of plastic to permit xray beam to pass through\\
* the back cover is constructed of heavy metal and serve to _______ scatter radiation

tubehead, reduce

duplicating film

used to make copies

has emulsion on one side only

duplicating film

the duplicating film is not exposed to xrays and must be used with what?

\
must be used in a darkroom!

be used with a film duplicator

how should film be stored?

kept in a cool, dry place

convert the latent image to a visible image

film processing

film processing

steps that produce a visible image on a dental image

during processing, the halide portion of the *exposed, energized* silver halide crystal is ________.

* what is this process called?
* what does it result in?

removed

* reduction
* results in precipitated black metallic silver

selective reduction

reduction of the energized, exposed silver halide crystals into black metallic silver, while the *unenergized, unexposed* silver halide crystals are removed from the film

what does the developer solution do?

it distinguishes between the exposed and unexposed silver halide crystals. it initiates a chemical reaction that reduces the exposed silver halide crystals into black metallic silver and creates dark or black areas on a dental radiograph

what does the fixer solution do?

it removes the unexposed silver halide crystals and creates white or clear areas on the dental radiograph

what is the visible image made of?

**made of black, white, and gray areas**

**radiolucent**

==readily permits passage of the xray beam==

**radiopaque**

==resists passage of xray beam==

why is automatic film processing often preferred over manual film processing?

**less processing time is required**

automatic processing steps

* development
* fixing
* washing
* drying

**daylight loader**

a light shielded compartment that can be used ==in a room with white light==

automatic processor

**automates all film processing steps**

advantage of automatic processor

* less time (4-6 min vs up to one hr for manual)
* automatic control of time and temp

==roller transport system==

move dental xray film through the developer, fixer, water, and drying compartments

* it also produce a wringing action to remove the excess solution from the emulsion as the film moves from compartment to compartment

how often should an automatic processor be cleaned?

==may require daily or weekly cleaning==

the processing solution levels in the automatic processor must be checked when?

in the beginning of each day and replenisher adder as necessary

manual film processing

1. development
2. rinsing
3. fixing
4. washing
5. drying

during which step is the film emulsion softened?

during the development step

rinsing

removes the developer from the film and stops the development process

during which step is the film emulsion hardened?

during the fixer stage

washing

thoroughly removes all excess chemicals from the emulsion

drying

==films must be dried before they can be handled for mounting or viewing==

* thisstep requires most time in the manual process

==film processing solutions may need to be changed more frequently when==

large numbers of film are processed

what are the two chemicals in the developing agent?

==hydroquinone: black tones and sharp contrast==

==Elon: shades of gray==

what is the optimal temperature for the developer solution

68 degrees F

\
hydroquinone is temp sensitive. it is inactive under 60F and very active above 80F

Name the following in the developer solution

* **preservative**
* **accelerator**
* **restrainer**

* **preservative:** sodium sulfite
* **accelerator:** sodium carbonate
* **restrainer:** potassium bromide

what is the purpose of the preservative?

prevent the developer solution from oxidizing in the presence of air

what is the purpose of the accelerator

to activate the developing agents

what is the purpose of the restrainer

to control the developer and to prevent it from developing the exposed and unexposed silver halide crystals

what are the ingrediants of the fixer solution?

* fixing agent
* preservative: prevent chemical deterioration of the fixing agent
* hardening agent:harden and shrink the gelatin in the film emulsion after the accelerator in the developer solution has softened it
* acidifier:neutralize the alkaline developer

an exhausted developer does not ______ develop the latent image

* produces an image with non diagnostic radiograph with reduced density and contrast

fully

an exhausted fixer does not _____ the chemical reaction sufficiently

* produces an image yellow-brown, transmit less light, and lose their diagnostic quality

stop

no light leaks can be present and can result in what

fogged images