The two basic layers of radiographic film are the _____ and the _____.
base and emulsion
Modern radiographic film base is made of _____.
polyester
The main purpose of the gelatin emulsion in radiographic film is to _____.
hold the silver halide crystals
Crystals in film emulsion consist of _____ and _____.
silver bromide, silver iodide
Latent image formation occurs during film _____.
exposure
A contaminant in the silver halide crystal creates the _____.
sensitivity speck
Direct exposure film has a _____ emulsion and _____ silver halide crystals than screen-film
thicker, more
The latent image can be seen _____.
only after development
Film is made with double emulsion to enhance film _____.
speed
Storing film in very low humidity conditions can cause _____.
static artifacts
Heart of xray film
emulsion
overcoat protects from
scratching, oils from handling, etc
Latent Image is
unobservable until processed
Manifest image is
observable image
Specks attract____ during image formation
free silver ions
Photons that interact with film
light or xray photons
Optimally charged film has ____ silver atoms at each sensitivity speck
4-10
More silver atoms produce _____ film
overexposed
Less silver atoms produce ____ film
underexposed
Elephant example
LONG trunk (long scale) Needs to duck LOW (Low contrast) Is GRAY Is LARGE (large grains) Is HIGH up (High Latitude)
Penguin example
They are SHORT (Short scale) Must jump HIGH (High contrast) Are BLACK AND WHITE Are SMALL (Small grains) Are LOW to ground (Low contrast)
____ grains are more sensitive than _____ which are faster.
Large, Small
All films respond to what color light
Violet and blue
What colors do films respond to if sensitive to it
Green, Yellow, And Red
Blue sensitive film uses _____ safelight
amber or red
Green sensitive film uses ____ safelight
red
Green and amber have similar _____
wavelengths
Intensity X Time =
constant optical density
Long or short exposure times will produce ____ speed
reduced
Direct exposure requires ____ times more radiation
10-100
Mammography uses ____ emulsion
single
High heat/humidity causes
fog
Low humidity/temperature causes
static
Maximum storage time for film
30 days
% of xrays that interact with film
1%
% of xrays that interact with screen
30%
Intensifying screen decreases ____ and increases ____
dose, image blur
protective coating is layer
closest to film
protective coating is ____ to light
transparent
phosphor is ____ layer of intensifying screen
active
Phosphor converts ____ to ____
xray bream, light
What does reflective layer do to light headed away from film
intercepts it and redirects it toward film
Base is ____ from film
furthest
Base is _____ support for phosphor layer
mechanical
Older screens were made of
calcium tungstate
Newer screens are made from
rare earth materials
Higher atomic # means higher
DQE
Conversion efficiency
amount of light emitted for each xray absorbed
Higher conversion efficiency, the _____ the patient dose
lower
higher conversion efficiency results in _____ noise
increased
luminescence
emission of visible light
2 types of luminescence
fluorescence, phosphorescence
Fluorescence
light emitted when phosphor is stimulated
Phosphorescence
light emitted during & after stimulation is terminated
Phosphorescence is called
afterglow
Relative # describes how
efficiently xrays are converted to light
MHLGGLL
ex-chest
More quantum Higher speed Larger phosphor Greater thickness Greater efficiency Less detail Less technique
LLSLLMM
ex-finger
Less quantum Lower speed Smaller phosphor Less thickness Less efficiency More detail More technique
Spatial resolution
Small objects with high subject contrast
When xrays interact w/ intensifying screen light is emitted ____
isotropically
Isotropic
equal intensity in all directions
Greater emulsion thickness, ____ spatial resolution
decreased
Great phosphor size, ____ spatial resolution
decreased
Direct exposure film is higher detail because of
no light spread