chapter 4 Flashcards
portion of image that is dark or black; structures that appear radiolucent permit the passage of xrays with little or no resistance(pulp chamber and pdl)
radiolucent
portion of the image that is light or white; structures that appear radiopaque are dense and absorb or resist the passage of xrays(enamel, dentin, bone)
radiopaque
degree of darkness or image blackening
density
light= how much density
little density
dark=how much density
more density
blackness results when xrays strike sensitive crystals
in the film emulsion
if you increase mA , density
increases
refers to the many shades of gray that separate the dark and light areas
contrast
high contrast image will have
few shades of gray
low contrast image will have
many shades of gray
high contrast between adjacent areas are
large
high contrast is __ scale
short
low contrast is ___ scale
long
where tissues are soft or thin
radiolucent
where tissues are hard or thick
radiopaque
radiographs in which the density differences between adjacent areas are small
low contrast
lower contrast is(color)
darker
increase kvp(raise), ____ contrast
low
decrease kvp(lower)
higher contrast
geometric factor that refers to detail and clarity of the outline of structures shown on a radiograph; can be affected by pixel size and distribution
sharpness
shadow cast rules are often referred to as a geometric factors that contribute to the ____ of a radiographic image
quality
rules for shadow casting
small focal spot
long target-object distance
short object-film distance
parallel relationship between object and film
perp relationship between central ray of xray beam and the object and film
scattered radiation add a uniform exposure to a radiograph that __ contrast
decreases
higher kv produce ___ contrast
lower
lower kv produce___ contrast
higher
regions with tissues of different densities will have__ contrast
Higher contrast
regions with tissues of similar densities will have ____ contrast
lower contrast
increased scatter radiation, ___ contrast
lower
small focal spot, what is sharpness
increase
long target image distance- sharpness
increase sharpness
short object image distance- sharpness
increase sharpness
thin screen- sharpness
increase
large crystals- sharpness
decrease
distance between the source of x ray production and the image receptor
target-image receptor
long target image receptor distance has x rays in the center of the beam that are nearly ___
parallel
long target image distance —
sharper image
less magnification
distance between the object being radiographed and the image receptor
object image receptor distance
closer proximity of object image receptor
shaper images and less magnification
thicker the screen, the___ radiation required to expose a film
less
the thicker the screen, the less
sharp the image
increase in size of the image on a radiograph compared to the actual size of an object
magnification
long PID does what to the magnification
decreases magnification
result of unequal magnification of different parts of the same object
distortion
long object image distance does what to magnification
increase
effects of varying the exposure factors(exposure factors listed)
- mA
- exposure time
- mAs
- kVp
if you increase mA, time and kV, the image density will do what and what color
darker and more dense image
increase kV for ____ contrast
less contrast
which will primarily affect image contrast, but secondarily affect image density
kV
combining the ____ with exposure time is an effective way to determine total radiation generated
mA
when mA is increased, the exposure time
must be decreased
as kV is increased, the ____ the wavelength and the _____ the energy and penetrating power of the xrays produced
shorter; higher
what is the only exposure factor to directly influence contrast
kVp
length of the target- surface distance is determined by the length of the_____
PID
sum of the target object and object image receptor distance
target image receptor distance
image quality improves when the target image receptor distance is_____
increased
states that the intensity of radiation varies inversely as the square of the distance from its source
inverse square law
inverse square law equation
original intensity/new intensity= new distance^2/original distance^2
when the target-image receptor distance is doubled, the radiation spreads out and the intensity does what
decreases by four
