Base Posterior/ Vertical Flashcards
Why is the projection ray “vertical”?
b/c central ray is directly vertical to the horizontal planted of atlas.
What is the primary purpose of the base posterior film?
To determine atlas rotation on side of atlas laterality
What is the secondary purpose of the base posterior film?
Integrity of odontoid and ring of atlas
How is the bucky positioned?
45 degrees with the bottom edge posterior
What is the vertical distance of the tube?
36-40”
What lines are constructed on the base posterior film?
- APL - atlas plane line
2. PSL - Perpendicular Skull Line
How do you construct APL on base posterior film?
Place dots in center of transverse foramens and draw line.
How is the + sign drawn?
Find like sets in orbit. Don’t draw line but scroll down to basilar process. Make + sign through these two dots.
How do you draw PSL?
Place dot on center of nasal septum. Draw line from there through + sign and down to PSL.
What is the first thing to do before measuring for listing?
Note side of laterality from Nasium film.
What side do you measure the angle from?
The side of laterality of the Nasium film.
If the angle is greater than 90 degrees then what is the rotation?
posterior
If the angle is less than 90 degrees then what is the rotation?
anterior
If the angle is = to 90 degrees, then what is the rotation?
NO rotation
How many letters is the listing if there is NO rotation?
3
