Density

Density is the overall blackening of the film and is related to the number of x-rays used. mAs is the primary controller of density. Excessive mAs results in an overly dense, dark film (the shoulder portion of the characteristic curve, optical density 2.5). Inadequate mAs results in a light film (the toe portion of the characteristic curve, optical density .25). Factors that affect radiographic density include:

mAs
SID
kVp
scattered radiation
intensifying screens
grids
filtration
the body
beam limitation devices
the anode heel effect
processing of the film