F. Film/screen compatibility—Color of light emission test

100 cm

set the FFD to blank

dim

(blank) the room lights to clearly observe the screen.

80 kV and 10s

Make an exposure using:

• High KV:

• Long exposure time (max time possible: blank)

note the color of emitted light and note the intensity

Observe the screen during exposure:

• note blank

• note blank

color of emitted light should match film sensitivity and intensity should be consistent across similar screen type

Evaluation: (2)

screen consistency test

Corrective Actions:

• If color mismatch is found:

→ Replace the film with one compatible with the screen's emission.

• If significant variation in intensity is observed between screens of the same type:

→ Check cassette labels and/or conduct blank

→ Re-label cassettes accurately as needed.

Calcium Tungstate and Rare Earth

two classification of IS

Blue light, has crystals, Higher than 0.2s or higher than 20 mAs

Calcium Tungstate (CaWO4)

Light color emitted:

Physical structure: (suspended in a phosphor layer)

Exposure Requirements: Needs longer exposure time (s) and higher dose

• 
  

Green light, Gadolinium Oxysulfide and Lanthanum Oxybromide, lower than 0.05s or lower than 5 mAs

Rare Earth 

Light color emitted:

Chemical Compositions:

Exposure Requirements: Needs shorter exposure

• 
  

color of light emitted = film sensitivity

SPECTRAL MATCHING FORMULA

unexposed film or image blur

if spectral mismatch occur, this leads to (2):