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sensitive to light & xrays
Direct exposure film
sensitive to xrays
The base of the film is made up of _______ and what are the four properties?
- 1. flexible
- 2. stable
- 3. rigid
- 4. uniformly lucent
what is the purpose of the adhesive of the film?
To glue the emulsion to the base
Describe the emulsion of the film, and what does duplitized mean?
- Made of gelatin w/ silver hallide crystals within
- Duplitized = emulsion on both sides of film
What is the most common silver hallide crystal?
Supercoat of Film
The protective layer of the film
What is the sensitivity speck made of and what is its purpose?
- Made of gold silver sulfide
- Purpose: attract free silver ions moving around (to neutralize it)
Sensitive to all colors of light
Sensitive to all colors of light BUT red
The unseen change in atomic structure (during exposure)
Gurney Mott Theory
- 1. Incident photon knocks electron from Br- atom
- 2. Ejected e- gets attracted to sensitivity speck, making it have a negative charge
- 3. Negatively charged sensitivity speck attracks free roaming Br (silver) ions, neutralizing the speck...resetting the trap.
- 4. 3 trapped silver atoms turns it to a black metallic silver (what makes film black)
Direct Exposure film
- Industry use
- Only xray sensitive
Screen Film, Photosensitive Film, Intensifying Screen Film-
- sensitive to light & xrays
- varies in film speeeeed
Amount of density a film produces for a given amount of exposure
Film that is an exact copy of a radiograph and is already presolarized
Exposing the film up to the point of the reversal phase, can only become lighter
what type of film is used for cerebral angiography?
Film should be stored______, at the temp of______, and _____ - _____ % humidity.
- on end
- 68 degrees F
- 30-60 %
The process of turning a latent image into a visible/ manifest image is called..
4 steps of automatic processing
- 1. developing
- 2. fixing
- 3. washing
- 4. drying
The reducing agent is part of the __________solution and consists of ______ and ______.
Phenidone provides ______ & ______ shades. It also works ______.
- fine detail & gray
Hydroquinone controls the _____, heavy shades of ______.
When P & Q work better together, its called?
- reducing agent gives up electron
- silver ion accepting an electron
The more exposure = _____ black metallic silver atoms = _______ film
creates an alkine enviroment, which makes the reducing agent work
prevents reducing agents from over reacting/ keep darkening the film
decreases oxidation of reducing agents when exposed to air (styrofoam)
controls swelling of the gelatin
Water (developer & fixer)
Fixer can't get into the developer due to the acidity of the fixer, if this would happen it would cause?
- Removes unexposed silver hallides from the film
- maintain fixer acidity
- makes the reducing agents stop working because of the low pH
- keeps fixer from being exhausted
- ammoniumthosilversulfate = ammoniumthiosulfate
- takes silver out = silver recovery
Archiving consists of 3 processes.
- Washing- gets excess fixer & developer from film
Too much fixer left on the film causes________ and is called _________.
- film to be yellow
- Fixer Retention
Transport system consists of...
- high # of flims going in/out of processor
- replenished w/ each new film
What type of replenishment system has.. low number of films, refills chemicals hourly, timer controlled, and helps with mixing new chemicals
flood replenishment system
Silver is found on ______ & ______. Its recovered by ____________________________
- fixer and film
- providing electrons to make black metallic silver
What has more sliver, developed or undeveloped?
The measure of characteristic responses the film has to exposure & processing is called?
This device is made up of aluminum and provides a range of densities on a film. Two names..
This device uses a light source, not an actual xray machine & is used to tell how well the processor is fucntioning.
What is the function of a desitometer?
To read the degree of blackening on a film
Optical Density formula...
Opacity formula and definition of ...
- Opacity = Io/It
- films ability to stop light
Other names for D log E curve (3)
- Hurter & Driffield (H&D)
B + F
- Base + Fog
- density of the film at no exposure
- controls grays early on
- controls blacks later on
Part of the curve where diagnostic info is found
straight line portion
- max. density the film is capable of recording
- -all the silver hallides have all the silver atoms they can except
- more exposure = less density
- - called solarization
- sharpness AND detail
- bigger crystal size = less resolution
- graininess = poor resolution
The amount of density a film produces for a given amount of exposure is called..
film speed is controlled by
Speed goes up = patient does decreases
phenidone (toe portion)
large crystal size = high speed= decrease in resolution= less patient dose (T or F)
thin emulsion = high speed= low resolution = less patient dose (T or F)
- False (thick emulsion)
Contrast in terms of the D log E curve is defined as
slope of the straight line portion
- straight line portion of D log E
- (OD .25 + b + f & OD 2.5 + b + f)
- what we can see
The width of exposures that will produce densities in the diagnostic range.....
- latittude increases = contrast decreases
Device inside the cassette that contains phosphors that absorb xray photons & emit light photons
1% xray, 99% light
Emission of light from intenisifying screen when stimulated by radiation
good phosphors, only emit light when exposed to radiation
phosphors continue to clow after the exposure has stopped
- AKA- screen lag, after glow
What is considered the active layer of the intensifying screen
what is the reflective layer of the intensifying screens job?
to reflect light back towards the film
single emulsion cassettes, what way does the film have to be placed in it?
- emulsion side of film down on top of intensifying screen
- creates less OID
Calcium Tungstate intensifying screen
old, glows blue
Rare earth intensifying screen, why used today (3 things)
- 1. greater absoprtion
- 2. better resolution
- 3. produces more light - glows blue & green
Intensifying screen speed
- capability of film to produce light
- high screen speed= less patient dose ( high kVp, low mAs)
Describe Quatum Mottle & what is the cure
- occurs when too few photons form an image
- less than 3 silver ions on sensitivity speck
- salt & pepper apperance
- Cure- high mAs, low kVp OR slower screen speed
good film screen contact creates...
- good resolution
- no hair/dirt b/w film and intensifying screen
Mwatching the color the phosphors of the screen glow to the sensitivity of the film is called...
- spectral matching
- spectral emission = color the screens glow
RS # goes up = patient does goes down = resolution goes down = fast film screen combo = less latittude
What is line spread function?
- measures the boundries
what is modulation transfer function?
- 5 lp/mm is what we can see (dont get tricked, 10 lines= 5 line pairs)
how is resolution limited?
by the intensifying screen
i'm disgusted with how many cards this turned into and i'm never typing them again. It gives my pinky a hinky feeling after I type too much.
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