Skull Positioning Flashcards
What IR is used for all skull images?
10x12
What is the SID for all skull images?
40”
What structures are seen for an AP Axial skull (Caldwell Method)?
- Entire cranium
- Orbits are equal distance from the skull borders
- Symmetric petrous ridges
- Petrous pyramids lie in the lower 1/3 of the orbit (if angle is used)
- Orbits appear magnified due to AP positioning
What breathing technique are skull views taken on?
Suspended respiration
What structures are seen for an PA Axial skull (Caldwell Method)?
- Entire cranium
- Orbits are equal distance from the skull borders
- Symmetric petrous ridges
- Petrous pyramids lie in the lower 1/3 of the orbit (if angle is used)
What structures are seen for an AP Axial skull (Towne Method)?
- Symmetric petrous pyramids
- Dorsum sellae seen projected within the foramen magnum
- Occipital bone and posterior portion of parietal bones are demonstrated
What structures are seen for an PA Axial skull (Haas Method)?
- Symmetric petrous pyramids
- Dorsum sellae seen projected within the foramen magnum
- Occipital bone and posterior portion of parietal bones are demonstrated
What structures are seen for a right/left lateral skull?
- Imaging side closest to IR
- Superimposition of TMJ’s, orbital roofs, mastoid regions, and greater wings of sphenoid
- Sella turcica in profile
- No overlap of cervical spine by mandible
What structures are seen for a submentovertical skull?
- Symmetric petrous pyramids
- Superimposition of mental protuberance over the anterior frontal bone
- Demonstrates cranial base
What is another name for the submentovertical skull?
Schuller method
What is another name for the schuller method?
Submentovertical
Where is the CR for a submentovertical skull (Schuller method)?
- Perpendicular to 10ML through sella turcica
- At MSP between mandibular angles at a level 3/4” anterior to EAM
When do you have to angle to CR for a submentovertical skull (Schuller method)?
So that it enters perpendicular to the IOML
For the submentovertical skull (Schuller method), the MSP is _______
Perpendicular to IR
How is the patient positioned for a submentovertical skull (Schuller method)?
- Patient is seated upright with head flexed back to place IOML parallel with IR
- May be done supine, but is more difficult for the patient
What is the CR for a right/left lateral skull?
Enters 2” superior to EAM
What baselines for the right /lateral skull must you check for accuracy?
- MSP
- IOML
- IP
Where must the MSP, IOML, & IP be for an accurate right/left lateral skull?
- MSP: Parallel to IR
- IOML: Perpendicular to front edge of IR
- Perpendicular to IR
Why must you check the MSP, IOML, & IP for a right/left lateral skull?
Accuracy
How is the patient positioned for a right/left lateral skull?
- Patient is either RAO or LAO
- Instruct them to “lie on their ear”
Why do we do a PA axial skull (Haas method)?
If the patient cannot be correctly positioned for the AP axial (towne method)
What view do we do if the patient cannot be correctly positioned for the AP axial (towne method)?
The PA axial skull (Haas method)
What is the angle of the CR for the PA axial skull (Haas method)?
25 degrees cephalic
What is the CR for the PA axial skull (Haas method)?
Enters 1 1/2” below the inion to exit 1 1/2” superior to the nasion
Why do you increase the kVp by 5 for the PA axial skull (Haas method) & AP axial skull (Towne method)??
To compensate for the large angle
What do you increase the kVp by for an AP axial skull (Towne method) & PA axial skull (Haas method)?
by 5
How is the patient positioned for the PA axial skull (Haas method)?
Prone with elbows flexed to place shoulders in the same horizontal plane
Where is the MSP & OML for a PA axial skull (Haas method)?
Perpendicular to IR
How is the patient positioned for an AP axial skull (Towne method)?
Supine
What is the CR for an AP axial skull (Towne method)?
Enters 2 1/2” above the glabella to exit at the foramen magnum passing through the level of the EAM
Where is the MSP & OML for an AP axial skull (Towne method)?
Perpendicular to IR
What is the angle of the CR for an AP axial skull (Towne method)?
- 30 degrees caudal
- 37 degrees caudal when using IOML
Where is the CR for a PA axial skull (Caldwell method)?
Exits at the nasion
How is the patient positioned for a PA axial skull (Caldwell method)?
- Either prone or upright
- Forehead and nose resting against the table or bucky
What baselines do we need to check for accuracy on an AP axial skull (Caldwell method) & PA axial skull (Caldwell method)?
MSP & OML
Where is the MSP & OML for a PA axial skull (Caldwell method)?
Perpendicular to IR
What angle is the CR for a PA axial skull (Caldwell method)?
- 15 degrees caudal
- 23 degrees caudal when using GML
Why would the petrous pyramids fill the orbits for an AP axial skull (Caldwell method) & PA axial skull (Caldwell method)?
If there is no angle
What would happen if there was no angle on an AP axial skull (Caldwell method) & PA axial skull (Caldwell method)?
The petrous pyramids will fill the orbits
Some protocols require ______ CR angle for a PA axial skull (Caldwell method)
No
When would a PA axial skull (Caldwell method) with a perpendicular CR?
If the frontal bone is of primary interest
What do you do to the CR during a PA axial skull (Caldwell method) if the frontal bone is the primary interest?
CR is perpendicular
Where is the CR for an AP axial skull (Caldwell method)?
Enters at the nasion
what is the MSP & OML for an AP axial skull (Caldwell method)?
Perpendicular to IR
How is the patient positioned for an AP axial skull (Caldwell method)?
- Either upright or supine
- Back of the head resting on table/bucky
What is the angle of the CR for an AP axial skull (Caldwell method)?
- 15 degrees cephalic
- 23 degrees cephalic if using GML
