Producing the Image Flashcards
Common problem that gives the radiograph an overall gray appearance and can be caused by numerous things
Film fog
4 factors of exposure
- kVp
- Milliamperes (mA)
- Time (fractions of a second)
- Distance (SID)
How much contrast is on the radiograph
Radiographic contrast
A result of the absorption characteristics of the anatomical tissue radiographed
Subject contrast
Collects scatter radiation under the table top
Grid
Eliminates soft rays
Filter
Changes the field of the x-ray
Collimation
Measurable difference between 2 adjacent densitites; bone vs. lungs
Quality of x-rays; “power” behind x-rays
Contrast
% of blackness
Quantity of x-rays
Density
What color does bone show up?
White
What color does soft tissue show up?
Grey
What color do gases show up?
Black
What color does metal show up?
White
Affects contrast
kVp
Affects density
mAs
Can affect the radiographic contrast
Time
Short scale of contrast
High contrast
Long scale of contrast
Low contrast
Most common artifact
pt movement
Low mAs results in
pale film
High mAs results in
overall black appearance
Period of time it takes for the x-rays to leave the tube
Fractions of a second
Time
The intensity of the radiation at a location is inversely proportional to the square distance from the source of the radiation
Inverse Square Law
Film exposed in 2 ways
Table top and grid
The distance between the tube and the film
SID
SID
source image distance
FFD
Focal Film Distance
Sante’s rule
(2 x thickeness in cm) + 40 + grid
