Film screen acquisition Flashcards
What are the parts of film holder or cassete?
cassette front
contact felt
hinges
cassette back
is the rigid, light-tight container that holds the screens and film in close contact
cassette
what is the recommended opening for the cassette when loading films?
2-3 inches
metal frame with low Z and radiolucent front
cassette front
what are the composition of cassette front?
magnesium
bakelight
carbon fibre
it is a compression layer that maintains the proper film-screen contact
contact felt
light tight seals is complete by a snap
hinges
it composes led foil
cassette back
what are the composition of cassette back?
manganese and lead
when is the first use of the IS?
1900
the IS acts as ____ that converts xray energy to light
transducer
made of polyester base with an active layer containing phosphors that produce visible light when struck by x-rays
Intensifying screen
poor contact of IS may results to
loss of recorded detail
blurring of the image
poor film screen contact may be calibrated by
wire mesh test
the IS allows ____ less radiation exposure
15-20x
what are the layers of the IS?
Base
Reflective layer
Phosphor layer
Protective coating
what is the thickness of the base of the IS?
1mm or 1000 micro meter
what is the thickness of the reflective layer?
25 micro meter
what is the thickness of the phosphor layer
150 -300 micro meter
what are the crystal size inside the phosphor layer?
5-15 micro meter
abillity to give off light
luminisence
what are the types of luminisence
phosphorescence
fluorescence
the ability of the phosphor to interact with x-ray
Detective Quantum Effciency
the ability of the phosphor to convert x-ray into light
Conversion efficiency
specific color that the phosphors emit must match with the spectral sensitivity of the film
Spectral matching
is insignificant in radiography but is used in fluoroscopy
minimum afterglow/ lag
what are the characteristics of good Phosphor
high DQE
High CE
Spectral matching
minimum afterglow/ lag
what is the thickness of the protective coating?
10-20 micro emter
what is the thickness of the protective coating?
10-20 micro meter
what are the phosphor materials?
-Calcium tungstate
-Barium lead sulfate or barium flourochloride
-Zinc Sulfide
-Rare earth
5% x-ray to light conversion
used with blue-sensitive films, has globular grains
calcium tungstate
used to produce high-speed screens for high kVp techniques
barium lead sulfate or barium flourochloride
used in flouroscopic screens
zinc sulfide
speed – 1000 to 1200, more efficient in converting x-rays to light. Only compatible to Orthochromatic films
Rare earth
speed – 1000 to 1200, more efficient in converting x-rays to light. Only compatible to Orthochromatic films
Rare earth
what is the desired KVp range for rare earths?
40-75 KVp
what are the selection of radiographic imaging system?
spectral sensitivity
spectral emission
spectral matching
capacity of screen to produce visible light
screen speed
what are the factors for screen speed of the IS?
-type of the phosphor used
-thickness of the phosphor
-crystal size
-reflective layer
-absorbing layer and dye in phosphor
if the screen speed is high, it can result to quantum mottle, therefore, what are the possible techniques to compensate it and create a high quality image?
lower the technical factor mainly the mAs
what are the screen speed measurement?
Intensification factor
Relative speed value
this is the intensification action of the IS
Intensification factor
what is the standard intensification factor?
30-50
this is the metric for the speed of IS
Relative speed value
please provide the general designating relative screen value
25- Ultra detail
50-slow/ high resolution/ detailed
100- standard/ medium/par
200-fast/ high speed
300- ultrafast/hi-plus
1200- rare earth
what are the relative speed value of the calcium tungstate?
30-50 (slow/detail)
100 (medium/par)
200 (high speed)
what are the relative speed value of the rare earth
100 (slow/detail)
300-500 (medium)
800- 1200 (fast)
incomplete contact across the entire surface to achieve maximum sharpness
screen film contact
how to calibrate screen film contactt?
wire mesh test with 150 KVp, 100 mA, 50ms, and 36-40 SID
what are the ways to take care of the screen?
-avoid abrasions and scratches
- regular visual exam to reveal dirt or speck
- UV light- to identify the stain
- clean regularly basis. use antistatic cleaner, 70% Isopropyl alcohol and 95 % to shorten the drying time
- mild soap and water, cotton for extra cleaning
it is the processing of image from latent image to manifest image
image processing/ film processing
what are the 6 steps in processing the film?
wetting, developing, rinsing, fixing, washing, and drying
what are the 3 main process to produce an image
technical factor, positioning, and processing
what are the 2 types of image processing
manual and automatic processing