what is the most common image receptor?
what is photosensitive film sensitive to?
light and x-rays
how is film constructed of?
What is duplitized film?
has emulsion and 2 sides (base is in the center and emulsion is on both sides
Base: material, properties, and coating
- Material: polyester
- Properties: Very flexable-very stable--very rigid--uniformly lucent
- Coating: blue dye- which cuts down on glare--also prevents the crossover effect and anticolasion
light from one screen to the next reducing the amount of glare
what is anticolasion
applied to the back of a single emulsion film. absorbs the light coming from the emulsion and prevents backscatter, visible light. or reflected light degrading the image
Glues the emulsion to the base and prevents bubbles when gets wet or bent
what is emulsion?
it is made of gelatin which allows crystals to spread out evenly with halide crystals in them.
Gelatin is used in the emulsion because it has the ability to swell and absorb the processing chemicals without dissolving
what is silver halide made of?
- Silver bromide or
- Silver iodide or
- silver chloride
silver bromide + silver iodide= silver iodobromide
Single emulsion layer film?
- Mammogram film
- duplication film
- extreme detail film
What is supercoat?
applied over emulsion to protect from skin oils. and scratching it also makes it very difficult to tear because of its hard protective gelatin
how should radiographic film be stored?
the process of manufacturing film?
- Crystal production
Crystal Production: chemical reaction-structure-sensitivity speck
Chemical Reaction: take place in total darkness it combines silver nitrate and potassium bromide in the presence of gelatin. The silver bromide will precipitate out and potassium nitrate can be washed away as a waste product.
Structure: small and are flat and rough and angular in shape
Sensitivity speck: gold-silver sulfide added to form- during latent emage formation the specks serve as electrodes to attract the free silver ion
what is gelatin for in crystal production?
to limin oxidatoin and reduce crystal surface energy tension, as well as to facilitate other chemical reactions
Cubic latice arrangement
the surfaces are primarily negative bromine and iodine halides, while the interior is primarily positive silver.
- size determines photosensitivity
- - the longer it ripens the larger it grows and becomes less resolution more faster and more photosensitive
- -Colored dyes added to certain types of film used with certain screens(wavelengths)
- -Hardeners prevent trauma to film
- -bactericide and fungicides prevent growth organisms
- -antifogging agents
how are films often classified?
- Panchromatic- film that is sensitive to all lights
- orthochromatic- not sensitive to red light (what we use in our darkroom)
- 1) Adhesive layer
- 2) emulsion layer
- 3) supercoat layer
latent image formation?
- Latent= before expose of radiograph
- manifest= what we see after exposed
- -unseen change in atomic structure
- -gurney and Mott theory
Gurney and Mott Theory?
- 1) a bromine ion absorbs and incident photon and ejects and electron
- 2) the ejected electron is trapped at the sensitivity speck, giving it a negative charge
- 3) the negatively charged sensitivity speck attracts a free silver ion
- 4) the silver ion neutralized at the sensitivity speck
- 5) repetition of the process deposits several silver atoms at the sensitivity speck
Film types ( not done)
- All manufactured for certain purposed
- Direct exposure- not sensitive to light on x-ray photons-- uses high dose used in industries- single emulsion, tiny crystals, thick emulsion layer, high silver content
Screen Film- fast film speed- faster darker- slower lighter
Special application film- mammo
- (different that duplitized)
- Duplication- exact copy of the radiograph
- use solarized film-- which is when film has been exposed long enough that it hits the reversal stage where it loses density
- = single emulsion film--not duplitized
- emulsion side should alway face downward
- Exact oposite--- if to light use less time--if to dark used more time
- used in cerebral angiograms
- =subtracts the bones and blackens the vessels (a long process--need to be very straight and precise)
- - now has been replaced by digital
- Age- Expiration on box
- Temp- 20 C or 68 F or lower (putting in freezers keeps it)
- Humidity- 30% - 60%
- No light-
- no radiation- lead lined film ben
- no chemicals-creates chemical fog
- on end- so don't get pressure marks
- Automated x-ray unit - bad w. film jams
- Daylight system- don't have to go in dark room it would load and unload cassette- also prone to jams
- -patient information flashed (patients name, DOB.....)
- -have R and L marker
- -if mistakes have to fix or redo