Materials used in recording Invisible x-ray image Flashcards
Layers of X-ray film
- Supercoat
- Emulsion layer
- Adhesive layer
- Base
- Adhesive layer
- Emulsion layer
- Supercoat
Base
- Provide support to the for the emulsion layer.
- Transmit light for the image to be viewed.
- Strong and flexible to withstand chemical stress
- Impermeable to water
- chemically inactive
- uniform in color
- non-flammable
Adhesive layer is made of what
Mixture of ;
*gelatin solution
* Solvent of film base
Adhesive layer
- ensures that the emulsion layer sticks to the base material during coating stage in manufacturing.
- Prevents any separation of the emulsion layer during processing.
Emulsion layer is made of what
*Silver halide crystals
they’re suspended in gelatin
Emulsion layer
Its where the invisible image is captured( latent image)
Gelatin
- A medium for growth of Ag
- Allows the film base to be evenly coated with warm liquid emulsion.
- Increase the ability pf AgH to store the latent image
- Holds metallic silver in place
- Permeable therefore it allows active ingredients to react with AgH during processing
Supercoat
- Made of pure gelatin
- Protect the sentive emulsion layer from light pressure or abrasions.
- Provide suitable surface characteristics( the film should be glossy to prevent dust accumulation)
Storage of x-ray films
- Temp ranges between 10 and 24 degrees celcius
- Humidity between 30% and 50%
- Should be stored in light-tight containers or cabinets
- Clean and dry environment( free from dust, dirt and moisture)
Intensifying screen
is a plastic sheet coated with fluorescent materials called phosphors.
Phosphors
Materials that convert photon energy to light
Luminescence
The emission of light from a substance bombarded by radiation.
Types of luminescence
- Fluorescence
- Phosphorescence
Fluorescence
Here luminescence only happens during the period of irradiation and will terminate at completion of the x-ray exposure.
Phosphorescence
The irradiated material continues to emit light after the exposure.
Uses of luminescent effect in radiography
- to obtain image on a fluorescent screen as in fluoroscopy.
- to increase the photographic response of the silver halide emulsion
Plastic base
Made of plastic material on which the phosphor material is coated.
Parts of an intensifying screen
- Protective layer
- Luminescent layer
- Reflecting layer (TiO2)
- Base
Reflecting layer of intensifying
intercepts light heading in other direction and directs it to the film.
Luminescent layer
Absorbs x-ray photons and converts them to visible light that is recorded on the film.
what materials are used to make the luminescent layer
phosphors
examples of phosphors
*Calcium tungstate( CaWO4)= Blue light
* Lanthanum oxybromide (LaOBr)= Blue light
* Gadolinium Oxysulfide(Gd2O2S): Green light
Characteristics of Intensifying screens
- Chemically inert
- Not discolor with age
- Radioparent base
- should not curl
X-ray cassettes
a light resistant container that holds the film between 2 intensifying screens.
Construction of x-ray cassettes
- The front is made of a low Z material to enable ease passage of x-rays. (plastic, carbon)
- The back is made of high Z material (lead to reduce back scatter)
Differences between x-ray cassettes used in conventional radiography and mammography.
- X-ray cassettes in conventional radiography have 2 intensifying screens mounted on two sides of the cassettes while in mammography only one intensifying screen.
Imaging plates
*Coated with photostimulable phosphors, used in CR.
* The phosphors store x-ray energy in gaps of the crystalline structure forming a latent image.
Layers of imaging plates
- Protective layer
- Phosphor
- Base
- Absorbing light layer
- Protective layer
- Label of code
Protective layer of the imaging plate
A thin, tough, clear plastic for protection of the phosphor layer
Phosphor/ active layer
Layer pf photostimulable phosphors, that traps and stores x-ray energy during exposure.
made of barium fluorohalide
Colour layer of the imaging plate
Influences the color of the light emitted during the reading process
Base
semi-rigid material that gives the imaging sheet some strength
Backing layer
soft polymer that protects the back of the cassette
Can you explain how intensifying screens enhance image quality in cassettes?
improve the quality of radiographic images by enhancing the effects of X-ray photons and reducing the necessary exposure, which benefits both the patient and the quality of the diagnostic image
