bisecting technique Flashcards
rule of isometry states
two triangles are equal if they have two equal angles and share a common side
radiographer must visualize a plane that divides in half (bisects) this angle
imaginary bisector
SIZE 2 intraoral receptor is used for all periapical projections
anterior region- receptor placed in the vertical direction
posterior region-receptor placed in horizontal direction
phalangioma
if the finger was positioned in front of the film instead of behind it. The image shows the pt finger
incorrect horizontal angulation results in
overlapped contacts
proper horizontal angulations result in
open contacts
vertical angulation (va)
the positioning of the PID in a vertical or up and down plane
central ray directed differently depending on the technique used:
paralleling-
bisecting -
- perpendicular to film & long axis of the tooth
- perpendicular to imaginary bisector
vertical angulation positioning (maxilla)
positioned above the occlusal plane and the central ray
directed downward, IS POSITIVE
vertical angulation positioning (mandible)
positioned below the occlusal plane and the central ray,
directed upward, IS NEGATIVE
incorrect vertical angulation
foreshortened image
the image appears shortened, vertical angulation is too steep
incorrect vertical angulation
elongated image
the image appears too long, vertical angulation is too flat
rules for bisecting technique
receptor placement.
use size 2 for both anterior and posterior
rules for bisecting technique
receptor position
placed against the lingual surface, 1/8 inch beyond incisal or occlusal edge
rules for bisecting technique
VA
central ray must be perpendicular to the imaginary bisector
