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44 Cards in this Set

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What are the two types of images created when performing an xray
Aerial - invisible pattern in air that represents various x-ray photons as they exit the object

Latent - invisible image on film that is produced in film emulsion after exposure to x-rays
What are the 4 types of receptors used in dental x-ray taking
Conventional -
intra and extraoral

Digital -
CCD(charged couple devices) and PSP(storage phosphor systems)
What is an image receptor
recording medium that displays information about an object that has been exposed to xrays
Describe some similar and differing qualities of the 2 types of conventional films
Intraoral- is a DIRECT exposure film and can give higher resolution, Used for bitewings and PA's

Extraoral - is an INDIRECT or screen film in other words it uses an intensifying screen that emits light. Extraoral used for pans and cephs

Both are harmed by exposure to ambient light
What is the functions of the lead foil layer in the film package
protects from backscatter, adds rigidity to package.

MAKE SURE YOU PUT SIDE WITH FOIL AWAY FROM SUBJECT

IS SIDE OPPOSITE THE DOT
What does the raised dot tell us
its on the film side and goes towards the xray tube--- used for film orientation
What is the function of the paper or plastic covering on the film package
Moisture resistant and protection from visible light
Should double film packages be processed at one time.
No they should be processed individually
What are the four parts of film composition
Base, adhesive, emulsion and protective coating
What are the base's functions in a film
its a thin clear plastice that is flexible and gives blue tint for easy viewing and reduced eye strain, supports emulsion,
describe the emulsion on a film
Its radiosensitive and records the image by interaction of xray photons or light
Why is emulsion coating on both sides of the film
To increase film speed, reduce exposure time and radiation dose
What is the main active ingredient of the emulsion
Silver Halide granules -
AgBr in F speed
AgI in ultraspeed(D speed)
Describe the vehicle matrix of the emulsion
gelatinous and non-gelatinous materials that keep Ag halides dispersed and absorbs processing chemicals

Its transparent(transmission of xrays and light) and very porous(chemical penetration)
What is the definition of film speed
also called Film Sensitivity - the amount of radiation required to produce an image of standard density or the efficiency with which a film responds to xray exposure
T or F Faster films need more radiation and longer exposure times
False, faster films need less exposure time and less radiation
What determines film speed
Size of silver halide granules - Larger the granule size faster the film speed
What are some of the benefits of faster films
decreased patient dose, short exposure time and less chance of motion
What are some of the characteristics of D speed films
round grain technology that gives high contrast, fine detail but requires higher dose than F speed. Uses AgI instead of AgBr like F speed
Describe F speed characteristics
Its a flat or tubular T-grain technology that gives 50% or more reduction in exposure compared to D. it has larger crystals and greater amount of AgBr in emulsion. Gives comparable contrast and resolution to D speed
F speed also accomodates a wider range of processing conditions and is exceptionally tolerant of processing variations
T or F film speed can be increased by processing at a slightly higher temp
T
however its not recommended as it can create fog and graininess
What can lower film speed
processing in diluted processing solution
Film fog is described as
unwanted blackness by exposure to radiation other than primary beam
What is film latitude
Measure of range of exposures that can be recorded as distinguishable densities on a film
Films with wide lattitude have what characteristics with respect to contrast
Lower contrast
What are the optimal storage conditions for xray film
50-70 deg F or 10-21 deg C
30-50 % humidity
What can storing film in dry conditions lead to
artifacts or static electricity marks on the processed film
When storing extraoral film boxes what should you take precaution in doing
store it on side of box to prevent warping
Open boxes should be stored in the xray room
false, store outside the xray room
What can storage of film in a refrigerator cause
condensation on film and black marks
What are some things that can cause film damage
Heat, light, bending and pressure
What are the four layers of the intensifying screen used for extra oral films
Base, reflector, Phosphor layer and overcoat
What is a synonym for extraoral film
screen film
What is the process that happens in an extraoral film which produces the image
Energy of xray beam converts to light by the phosphors in the intensifying screen being exposed to radiation. this light exposes the film to form the image
What are the properties of an intensifying screen
sturdy, moisture resistant, chemically inert, flexible and contains no impurities
What are the intensifying screen materials
Calcium tungstate(blue)
Rare earth phosphors used as intens screens
1 Gadolinium oxysulfide(green)
2 lanthanum oxybromide(blue)
3 yttrium tantalate (blue)
Why do manufactures recommend matching emission and absorption characteristics of intensifying screens and films
Different intens screens have different emissions and different films have different absorption characteristics
What are some of the effective doses of the different types of intensifying screens
Calcium Tungstate - single panoramic 14 microsieverts

Rare earth Intensifying
single panoramic - 7 microsieverts

NOTE Poster - Anterior View 7-17 microsieverts but not sure if this is shows difference between 2 types or is an estimater for rare earth's
Which type of intens screens require less radiation dose
Rare Earth
What are some advantages and disadvantages of extraoral film
Advanatges
Reduced patient dosage
diagnostically acceptable image

Disadvantages
lack of fine anatomical detail
What are some of the uses of extraoral films in dentistry
Panoramic, Post-Ant or Lateral Cephalometric
What are the most common causes of poor screen-film contact
Worn contact area
loose or bent hinges
warped screens caused by moisture
warped cassette front
cracked cassette frame
foreign matter under the screen
what are some function of grids
used to reduce scatter radiation
placed betweem subject and film
only used when increased contrast is needed
What is a disadvantage of grids
Higher exposure is needed(approx double)