Dental X-Ray Image Characteristics Flashcards
what are the geometric characteristics
sharpness
magnification
distortion
sharpness
detail, resolution, definition
how well the smallest details of an object are reproduced
penumbra
unsharpness or blurring of the edges
fuzzy unclear area surrounding tooth
sharpness influencing factors
focal spot size: shape and size influence the resolution
movement: of tubehead, receptor or patient
sharpness: focal spot
tungsten target of anode
concentrates electrons
smaller = sharper image
larger = loss of sharpness
sharpness: movement
slightest movement results in unsharpness
-may cause undiagnostic image
-image outline blurred
magnification
image appears larger than actual size of object
diverging x-ray beam
x-rays travel in diverging straight line, radiating from focal point
magnification influencing factors
target-receptor distance
object-receptor distance
magnification: target-receptor distance
distance between source of x-rays and receptor
determined by length of PID
longer PID and target-receptor distance = less image magnification
shorter PID and target-receptor distance = larger magnification
magnification: object-receptor distance
distance between tooth and receptor
ideal is close together as possible
decrease in O-R distance = decrease in magnification
increase in O-R distance = increase in magnification
bisecting causes more or less distortion
more
distortion: dimensional distortion
variation in true size and shape of object
results unequal magnification of different parts of same object
from improper receptor alignment or beam angulation
distortion: influencing factors
object-receptor alignment
x-ray beam angulation
distortion: object-receptor alignment
tooth and receptor must be parallel to each other
foreshorten and elongation
not parallel results in angular relationship
distortion: x-ray beam angulation
central ray must be perpendicular to the long axis of the tooth and the receptor to record adjacent structure in their spatial relationship
