If you manually process a film, what is the minimum time a film must stay in the fix before it can be briefly viewed and exposed to room light?
What is the RULE OF THUMB for manual processing?
Fix the film twice the developing time
What is the inverse square law for SID?
double the distance from the tube to film means 1/4 radiation reaches film ( decrease film density )
What are the 3 functions of a radiographic cassette?
1. To provide close, tight contact between the film and the intensifying screen. 2. Provide a light-tight container for the film 3. Protect the screen and film from physical damage
What are the two types of radiographic cassettes?
Aluminum and Plastic
Why is the radiographic cassette lined with metallic back?
to prevent backscatter
Wha size is the rectangle of lead on the front that allows use of the photoimprinter?
7 X 3cm
What are the four functions of intensifying screens?
1. Line front and back of cassette 2. Made of plastic sheet coated with PHOSPHOR material suspended in binding agen 3. Emits light when exposed to x-rays 4. reduces the amont of scatter radiation necessary to expose film (*****)
The screen speed is demermined by the size of the _________ _________.
What are the four characteristics for high speed screens?
1. Larger crystals 2. less radiation needed 3. poorer resolution 4. more graininess
What are four characteristics for slow speed screens?
1. Smaller crystals 2. More radiation needed 3. better resoultion 4. less graininess
Do high speed screens have larger or smaller crystals?
Do slow speed screens have larger or smaller crystals?
(S for slow and smaller)
What are the 3 different types of intensifying screens?