the portion of an image that is dark or black
radiolucent lacks density
that portion of an image that appears light or white
the overall blackness or darkness of a dental image
nondiagnostic
black areas (such as air spaces
white areas ( including enamel,dentin, and bone)
gray areas ( ex soft tissue)
image appears darker
density decrease and image appear lighter
the density inceases and the image appear darker
density decreases and image appear lighter
the more x-ray photons reach the receptor and continue to darken the image
the difference in the degree of blackness ( densities) adjacent areas on the dental image
when viewed on a light source a dental image that has very dark areas and very light areas
an image that does not have very dark and and very light areas but instead has many shades of gray
refers to the chracteristics of the film that influence radiographic contrast
deremined and controlled by the film manufacturer and cannot be changed
is under the control of the dental radiographers
high contrast
size and thickness of patient tissue
low subject contast----> and many shades of gray are seen on the dental radiographs
high subject contast-------> areas of black and white are seen on the image
contrast
are better able to penetrate tissue
low or decreases contrast -----> radiograph exhibits many shades of gray
high or increased contrast ------> radiograph has many black and white areas
the range of useful densities seen on a dental image
an image show only 2 densities
black and white areas
lowe kilovoltage --> high contrast
many densities or many shades of gray
high kilovoltage
low contrast
short scale contrast is beneficial
a short scale contrast may help allow the radiocent carries stand out because it demostrated more of the black and white areas
increase kilovoltage --> produce long scale contrast : beneficial to see subtle in bone loss associated with periodontal disease
maxilary and mandibular allowing the caries to be better viewed
uniform-layered thicknesses
sharpness
magnification
distortion
the sharpness of an image influanced by
focal spot size
movement
ranges from 0.6 to 1,0 mm2 and determined by the manufacturer
the smaller the focal spot size the sharper the image
fast films -->contain larger crystals that produce less image sharpness
lower fims contain smaller crystals that produce more image sharpness
more movement less sharp is the image
appears larger than the acual size
use the langest targest receptor distance and shortest object receptor distance
portion the receptor and the tooth parallel to each other and direct the x-ray beam prependical to the receptor and the tooth