Imaging the film Flashcards
what is a latent image?
invisible image formed on xray film after the xrays have hit the crystals
How is a latent image produced?
xrays interact with crystals and form a latent image and light production
How does a latent image become a visible image?
crystals absorb xrays and split apart- turn black. once the film is developed- latent image is converted into visible image
wide latitude
small crystals, slow screen, more detail, low grain, more radiation, slow speed
narrow latitude
large crystals, fast screen, less detail, high grain, less radiation, fast speed
four layers of intensifying screens
base, reflective, phosphor, protective
purpose of intensifying screens
aids in converting the xrays to light after they have penetrated patient
Calcium tungstate (quality, light produced, color)
emits blue. turns green
rare earth (quality, light produced, color)
emits green. better. turns purple
photo imprinting is
embedded on film
photo imprinting occurs…
before processing and after radiation exposure
cassette holds
film
intensifying screen is found
inside the cassette
the front of the cassette and back are what colors
front- black
back- blue
xrays cannot penetrate …
lead
when the xrays hit the film- turns
black
if no xrays hit the film.. turns
white or clear
intensifying screens are light dependent upon what components
phosphor
calcium tungstate and rare earth emulsions
Ca Tungstate- 30-40%
rare earth- 50-60%
film has what resolution
infinite
made of plastic/polymer, indestructible
base layer
reflects light emitted by phosphor layer back towards the xray film
reflective layer
converts the absorbed xrays to light, calcium tungstate & rare earth
phosphor layer
clear coating on the outer surface of the screen, protects phosphor layer and reduces static.
protective layer
which screen speeds are used in vet med
medium and regular
slow screens require more
radiation
small crystals creates more
concentrated
which screens have thick emulsions
fast screen
two types of luminescence
fluorescence, phosphorescence
composition of xray film
base, adhesive, emulsion, supercoat
high quality gelatin that is translucent. contains 3 crystals that we call silver halide
emulsion
the exposure range over which acceptable densities are produced
film latitude
accepts variations in exposure factors or processing without a major change in density
wide latitude
storing film near formalin, h2o2, ammonia, or radiation will cause
film fog
