Brightness and Contrast Flashcards
an object less effective in absorbing/blocking x-ray radiation
radiolucent
in radiolucency, more x-rays reach ____ and object looks ____
receptor, dark/black
in radiopacity, less x-rays reach receptor and object looks ____
light/white
term that refers to the degree of white (vs dark) of an object on a digital image/radiograph
brightness
radiopacity/radiolucency are _____ terms
relative
observed differences in adjoining radiographic densities
radiographic contrast
contrast is caused by ____ _____ of x-ray beam
differential absorption
great contrast is ______
“black and white”
low contrast is more _____
“gray”
contrast is influenced by…
chemical composition thickness density noise beam energy/penetrability exposure time/mA
chemical composition opacity rank (highest to lowest)
metal
enamel
dentin/bone
soft tissue
the higher the density of material, the more _____
radiopaque
material density opacity rank (highest to lowest)
metal enamel cortical bone/dentin trabecular bone soft tissue
the thicker the object, the more _____; the longer the path an x-ray beam travels through a material, the more ______
radiopaque, radiopaque (egg example)
incorporation of image information from scattered photon results in statistically random sign intensity
noise
how is noise measured?
sign to noise ratio (SNR)
noise contributes to…
- decreased ability to detect contrast differences
- decrease ability to detect edges
lower dose leads to
lower SNR
ability to see difference between grayscale value
contrast resolution
can see a small difference in greyscale value
high contrast resolution
can only see larger differences in greyscale value
low contrast resolution
which is more desirable, low or high contrast resolution?
high contrast
