LRA-226 Skull Series Positioning

Question 1

what is the clinical indication or reason for an AP axial/Townes view of the skull?

Answer 1

• skull fractures (medial/lateral displacements)
• neoplastic processes
• paget disease

Question 2

what is the body position for an AP Axial Skull/Townes method?

Answer 2

• flex or depress the chin to line up the OML with the EAM
• OML must be perpendicular to the IR

Question 3

what is the CR to an AP axial skull/Townes method?

Answer 3

• 30 degrees caudal to the OML
  glabella
• 2.5 inches above the glabella

Question 4

what anatomy is demonstrated in an AP axial/Towne’s method?

Answer 4

• occipital bone
• petrous pyramid
• foramen magnum
• petrous ridges are symmetrical
• dorsum sellae
• posterior clinoid process

Question 5

what is the clinical indication for a Lateral view of the skull?

Answer 5

• skull fractures
• neoplastic processes
• Paget’s disease

Question 6

what is the body position for a Lateral view of the skull?

Answer 6

• have face at a true lateral with no rotation
• side of interest closest to the IR
• OML must be aligned with the EAM
• alignment parallel to the IR

Question 7

what is the CR for a lateral skull?

Answer 7

• CR perpendicular to the IR
• 2 inches superior/above the EAM

Question 8

what anatomy is demonstrated in the lateral view of the skull?

Answer 8

• entire cranium visualized
• parietal bones superimposed
• view entire sella turcica and dorsum sellae
• no rotation or tilt

Question 9

what is the clinical indication for a PA axial skull?

Answer 9

• skull fractures (medial/lateral)
• neoplastic processes
• paget’s disease
• intended to demonstrate the frontal bone and minimal distortion

Question 10

what is the body position for a PA axial skull?

Answer 10

• rest the patient’s nose and forehead against the IR
• flex the neck to line up the OML to the EAM perpendicular to the IR

Question 11

what is the CR to a PA axial skull?

Answer 11

• exit of the glabella
• CR perpendicular to the IR

Question 12

what anatomy is demonstrated in the PA axial skull?

Answer 12

• frontal bone
• crista galli
• internal auditory canals
• frontal and anterior ethmoid sinuses
• petrous ridges
• greater and lesser wings of sphenoid
• dorsum sellae
• no distortion
• petrous ridges at level of SOM
• equal distance between orbits

Question 13

what is the clinical indication for a SMV/submentovertical cranium?

Answer 13

• advanced bony pathology of the inner temporal bone structure (skull base)
• possible basal skull fracture

Question 14

what is the body position for an SMV/submentovertical skull?

Answer 14

• over extend the head to line up the IOML to the EAM
• IOML and EAM are parallel to the IR

Question 15

what anatomy is demonstrated in an SMV/submentovertical skull?

Answer 15

• foramen ovale and spinosum
• mandible
• sphenoid
• posterior ethmoid sinuses
• mastoid processes
• petrous ridges
• hard palate
• foramen magnum
• occipital bone
• no rotation
• no tilt

Question 15

what is the CR for an SMV skull?

Answer 15

• 1 1/2 inches inferior/below to the mandibular symphysis
• CR perpendicular to IOML

Question 15

what is the SID for the skull projections of AP, PA, lateral, and SMV?

Answer 15

40 inches SID

Question 16

what is the size of the IR needed for a skull series?

Answer 16

10 x 12 inches

Question 17

if the patient cannot flex their head when positioning for an AP skull, what changes must be made?

Answer 17

• change CR angle to 37 degrees caudal
• instead of OML, IOML will be perpendicular to the IR