Lecture 6-Skull Flashcards
How do you acess for rotation in a Caldwell skull?
Look at the distance between the orbits and the side of the skull
Where should the petrous ridges be in a Caldwell skull?
Petrous ridges in lower third of orbits
How do you position for a PA caldwell projection?
-Erect PA
-MSP and OML perpendicular to IR
What angle is used for a PA caldwell projection?
15 degrees caudad
What angle is used for an AP caldwell projection?
15 degrees cephalad
What projection is this? What error(s) have been made?
-PA caldwell
-Only needed to collimate to the base of skull
What corrections need to be made to this iamge of the PA caldwell skull?
-Angle 10 degrees more caudad
-Lift the chin so the OML changes 10 degrees
-Rotate nose to the left
If the petrous ridges are in the middle of the orbits in a PA caldwell, what was the angle that was most likely used?
10 degree caudad angle
What corrections need to be made to this image of the PA Caldwell?
-Need to angle caudad an extra 5 degrees or raise the chin so that the OML changes by 5 degrees.
-Nose needs to be rotated towards the right (opp to odontoid rules)
What correction needs to be made to this image of the PA caldwell?
-Nose needs to be rotated towards the left
-Angle 10 degrees more caudad or lift the chin so OML changes by 10 degrees
What errors have been made to this image of the PA caldwell?
-Petrus ridges in a good spot
-Clipped vertex, too much of mandible on image
-Centered incorrectly
What would happen to the petrous ridges in this image if we were to center correctly? What would we have to do to correct this?
Petrus ridges would be too low, so we would have to decrease the caudad angle by 5 degrees or flex the neck so the OML changes by 5 degrees
What corrections need to be made to this image of the PA caldwell?
-Nose needs to be rotated to the right
-Petrus ridges in the middle; increase the caudad angle by 5 degrees, lift the chin 5 degrees
What corrections need to be made to this image of the PA caldwell?
-Extend the neck (looks like a Ruggles with no angle)
-Need to angle 25 degrees
Do we repeat for tilt in skull images?
No
Do we repeat for rotation in skull images?
Yes, most of the time
What errors have been made to this image of the PA caldwell?
-Vertex to the right
-Too wide FOV
What do we hit first in an AP Caldwell?
The orbits
What corrections need to be made to this image of the AP caldwell?
-Decrease the cephalad angle used (don’t need to specify the number) or tuck the chin down
-Rotate the nose to the right slightly
What corrections need to be made to this image of the AP caldwell?
-Rotate the nose towards the right
-Decrease the cephalad angle used or flex the neck
What corrections need to be made to this image of the AP caldwell?
-Center higher, collimate, and rotate nose the right
This would change the position of the petrous ridges so therefore no angle change required
T/F
The waters method is done AP and PA
True
Where should the petrous ridges be in a waters method?
Petrous ridges below maxillary sinuses or maxillary antrum
What two peices of anatomy is the waters method done for?
Sinuses
Facial bones
What angle is used for the sinus waters method?
No angle
When the MML is perpendicular to the IR, what is the angle of the OML to the bucky?
Angle of the OML=37 degrees from the IR/bucky
How do you position for a sinus waters method?
-Have patient open mouth while maintaining OML angle of 37 degrees (MML perp.)
-Horizontal ray
-Midline – exits at acanthion
-Collimate to edge of orbits, and hairline to below open mouth
What sinus does the waters method for the sinuses demonstrate?
Sphenoid sinuses are demonstrated through the open mouth.
What is the collimation for the facial bones waters?
Collimate to include zygomatic arches, and hairline to include the mandible
How do you position for a waters method for the facial bones?
-Erect facing IR
-Chin resting on bucky
-OML 37° from bucky
OR
-MML perpendicaular to IR
-MSP perpendicular to IR
What is the bottom of the maxillary sinus called?
The antrum
What projection is this? What errors have been made?
-Waters method-sinuses
-Could have collimated side to side more
What correction needs to be made to this image of the waters sinuses?
-Collimate more side to side
-Need to extend the neck more (petrous ridges too high)
-Nose needs to be rotated the left
-Vertex needs to be tilted to the left
What corrections need to be made to this image of the waters sinuses? Would this be a repeat?
-Need to flex the neck
-This would be a repeat because the teeth obscure the sinus
T/F
-If petrous ridges at bottom of the maxillary sinus for a waters sinus method, we need to repeat the image
False-That is good positioning
What correction needs to be made to this image of the waters sinuses?
-Nose needs to be rotated to the right
-Vertex needs to go to the left
What corrections need to be made to this image of the waters sinuses?
-Extend the neck more
-Rotate nose the right
What correction needs to be made to this image of the waters facial bones?
-Neck could be extended more
What error has been made in this image of the waters facial bones?
-Tilted to the left slightly
What correction needs to be made to this image of the waters facial bones?
-Need slight extension
Is this image of the waters sinuses a repeat? Why or why not?
Yes because the petrous ridges are filling the maxillary sinuses
What projection is this? What errors have been made?
-Lateral skull
-None; good positioning
How do we acess for tilt in the lateral skull?
By looking for superimposition of the orbital plates
Where should the TM joints and the EAM be in a lateral skull?
Both sides of the TM joints and the EAM should be in the same vertical plane
(should’nt be seeing two of each)
Where should the top of the skull be in relation to the IR in a lateral skull position?
Top of skull parallel to top of IR
How do we access for tilt when positioning a lateral skull (looking the patient prior to imaging?
Making sure the IPL is perpendicular
How do you access for rotation on the patient in a lateral skull?
Making sure the MSP is parallel to IR
T/F
To acess for rotation in a lateral skull, look at the position of the zygomatic arches.
False; DO NOT EVER TALK ABOUT THE ZYGOMATIC PROCESSES ON A LATERAL SKULL
-Zygomatic process are too far away so we cannot access (for every one inch, 1.5 degree difference)
How do you acess for rotation in the image of a lateral skull?
Look at the condyles of the mandible
What errors have been in this image of the lateral skull?
-Could have collimated more
-Tilt present (more magnified anterior and inferior); vertex was tilted towards the right
What should the spine look like in a lateral skull position?
Spine should appear like an oblique
What errors have been made in this image of the lateral skull?
-Top is clipped
-Neck too flexed
What would happen if we centered higher without changing any positioning?
Would project the right orbital plate inferior
What error has been made in this image of the lateral skull?
-Slight amount of rotation
-Chin flexed
-Shoulders not obliqued
How do you acess for rotation and tilt in the lateral orbits?
By looking at the position of the zygomatic processes
What error has been made in this image of the lateral orbits?
Nose rotated away from IR
What correction needs to be made to this image of the lateral orbits?
-Tilt the vertex to the left
-Rotate the nose to the right
For the AP mandible, do we want the image to look more like a ruggles or a caldwell? Why?
Ruggles; seeing a lot more ramus and body un superimposed
What projection is this? What errors have been made?
AP/PA mandible
-None-Good image
How should the AP/PA mandible be positioned?
-OML and MSP perpendicular to IR
-Perpendicular MSP– midway between EAM and syphysis menti
What error has been made in this image of the AP/PA mandible?
Chin extended too much-Mandible being foreshortened
What error has been made in this image of the lateral mandible?
-Nose rotated to the left-Don’t look at Z processes
-Right as to be the lower one because of the diverging beam
What errors have been made in this image of the lateral mandible?
-Too wide FOV
-Vertex tilted towards the IR
-Nose rotated towards the IR
Look at the entire ramus
What error has been made in this image of the lateral mandible?
None
What correction needs to be made to this image of the lateral mandible?
-Center down
-Collimate
How do you position for a lateral mandible?
-True lateral - IPL perpendicular to IR
-MSP parallel to IR
-IOML perpendicular to front edge of the IR
