dental image characteristics Flashcards
radiolucent
radiograph that is dark or black. Lacks density and permits the passage of the x-ray beam with little or no resistance
radiopaque
appear white or light on the radiograph, occurs when x-ray cannot pass through the structure and is very dense
contrast
ranges from gray - black to white
high contrast=
radiograph that has very dark & very light areas
90kV
film density increases and radiograph appears darker
70 kV
film density decreases
long scale
shows many densities, shades of gray.
short scale
shows only two densities, areas of black and white
Kv decreases=
high contrast= short scale
kV increases=
low contrast= long scale
consists of the uniform layered thickness of an x-ray absorbing material, usually aluminum. Monitor quality of the film and film processing
step wedge
density
overall blackness/darkness of the film
density
black spaces=
white spaces=
gray spaces=
black- air spaces
white-enamel, dentin, bone
gray- soft tissue
influence on density /contrast
low kV/ mA =
high kV/mA=
low density and high contrast
very high density and very little contrast
what do you have to increase that will increase density
kV, mA, exposure time
if a patient is thicker, fewer Xrays reach the film, and result an image has
less density and appears lighter
penumbra
the fuzzy or blurred area around the image
sharpness
Xray receptor to reproduce distinct outlines of an object
magnification
the image appears larger than the actual size of the object
distance between the object being radiographed and the dental x-ray film
object receptor distance
ORD decreases
decrease magnification
ORD increases
increase magnification
occurs when film is not placed far enough in the center of the mouth and the film must be angulated to avoid the slope of the palate
distortion
factors that influence increasing of intensity
increase kVp, mA, time
target surface distance=
x-ray to skin
target object distance=
x-ray to tooth
target receptor distance=
x-ray to film
the intensity of radiation is inversely proportional to the square of the distance from the source of radiation
inverse square law
source of radiation to the film is increased
the intensity of the beam is decreased
