Odds for Radiographic Test Friday, 4th Flashcards
The immediate emission of light during stimulation is characteristic of
fluorescent phosphor
Film speed can be increased by
increasing crystal size and increasing emulsion thickness
As the speed of a film screen system increases
image resolution decreases, quantum mottle increases, and noise increases
The resolution of an intensifying screen can be improved by
using light-absorbing dyes
Poor film screen contact is more prevalent with
large cassettes
The image on the radiographic film after exposure but before development is
latent image
If numerous negative density “white” artifacts are observed on a radiographic image, which actions should be taken?
clean the intensifying screen with appropriate solution
The use of intensifying screens will
reduce radiographic exposure and reduce patient exposure
The emulsion of a non-screen film is thicker than the emulsion of a screen film.
True
The purpose of the felt cushion in the cassette is
to improve film-screen contact
Which of the following is a requirement in the construction of the cassette front?
must be radiolucent
Film should be stored in a ____ ____ environment.
cool dry
Which type of illumination is desirable in an intensifying screen?
fluorescence
The property of certain chemicals to absorb radiation and emit light is
luminescence
What part of the intensifying screen intercepts light photons going in various directions and redirects them to the film?
reflective layer
List and explain the 4 characteristics a material should have to be used as a phosphor in an intensifying screen.
conversion efficiency, DQE, afterglow, spectral matching
conversion efficiency
convert more x-ray to more light
DQE
increases Z# to increase absorption efficiency
afterglow
should only fluoresce, not phosphorous
spectral matching
correct color of light from screen to match sensitivity of film
Screens with a thick active layer will display higher speed and greater detail than screens with a thinner active layer.
False
Screens should be cleaned with a mild detergent and paper towel.
False
gadolinium, lanthanum, yttrium
rare earth phosphors
Which of the following are components of radiographic film?
emulsion, polyester base, silver halide crystals
latent image
the image on the radiographic film after exposure but before development
orthochromatic film
sensitive to yellow-green light, red light is used during exposure
panchromatic film
sensitive to all color lights, no light is used during exposure
conversion efficiency
is where the phosphor should emit a large amount of light per x-ray absorption
absorption efficiency
a high Z# in the phosphor so that x-ray absorption is high
crossover
is when light goes through the top emulsion, through the base, and to the bottom emulsion. it affects recorded detail, due to the spreading of detail
