Skull

Question 1

What are the three skull types?

Answer 1

1. Mesocephalic (average)
2. Dolichocephalic
3. Brachycephalic

Question 2

angle between petrous ridges and MSP for mesocephalic skull?

Answer 2

47

Question 3

angle between petrous ridges and MSP for brachycephalic skull?

Answer 3

54

Question 4

angle between petrous ridges and MSP for dolichocephalic skull?

Answer 4

40

Question 5

what is the cephalic index?

Answer 5

width (parietal eminences)/length (frontal eminence to inion x100

Question 6

*Cephalic ranges for the skull types?

Answer 6

Mesocephalic - 75 to 80
Dolichocephalic <75
Brachycephalic >80

Question 7

Landmarks slides 9-12

Answer 7

IPL - interpupillary line
MSP
Glabella
Naison
Acanthion
Mental Point
Gonion
TEA
SOM - supraorbital margin
EAM
IOM - infraorbital margin

Question 8

what part of the eye does the outer acanthus represent?

Answer 8

the middle

Question 9

Slide 13

Answer 9

MML - mentomeatal line
LML - lips-meatal line
AML - Acanthiomeatal line
GML - Glabellomeatal line
OML - orbitomeatal line
IOML - Infraorbitomeatal line - reids base line
GAL - glabelloalveolar line

Question 10

*what is the difference between the GML and OML?

Answer 10

8 degrees

Question 11

• what is the difference between the OML and IOML?

Answer 11

7 degrees

Question 12

positioning considerations of the skull?

Answer 12

• Indications – pathology vs trauma
• Skull type or body habitus
• CLEAN BUCKY , IR or TABLE FIRST (must be witnessed by patient)
• Wash your hands
• Always sit your patient
• Radiation Protection - PA

Question 13

breathing instructions for all skull views?

Answer 13

“breathe in, hold your breath, don’t breathe, don’t move”

Question 14

What are you protecting in skull imaging doing the image PA?

Answer 14

the patients eyes

Question 15

patient prep - remove?

Answer 15

Remove necklace, earrings, piercings, GLASSES
- hair - no ponytails

Question 16

Lateral Skull

Answer 16

• Lateral Projection (typically Left Lateral position)
• MSP is parallel to IR - Oblique shoulders so the head is against the bucky (NOT like doing a lateral c-spine)
• Interpupillary line (IPL) is perpendicular to bucky
• IOML is parallel to the ground or perpendicular to front edge of the IR
• Main goal is to make the top of the head parallel to the top of the IR
  CP 2” or 5 cm superior to EAM
  Collimate

Question 17

TEA is a good landmark for?

Answer 17

top of petrous ridges

Question 18

Lateral image criteria

Answer 18

• Orbital plates are superimposed
• TM Joints (mandibular condyles) are in the same vertical plane
• EAMs’ are in the same vertical plane
• Sella Turcica is in profile

Question 19

Lateral positioning fault - tilt

Answer 19

• IPL is not perpendicular to the IR or bucky
• Orbital plates will not be superimposed

Question 20

Lateral Positioning fault - rotation

Answer 20

• MSP is not parallel to IR or bucky
• TM joints or mandibular condyles will not be superimposed posteriorly
• EAMs’ will not be in the same vertical plane

Question 21

PA Projection - Ruggles method

Answer 21

• Forehead & nose on upright bucky
• OML Perpendicular
• Midsagittal Plane (MSP) perpendicular
• CR - perpendicular
• CP - Halfway between vertex and base of skull
• Top of the petrous ridges must be at the top of the orbits - Petrous ridges fill orbits - BEST demonstrates IAC’s - Interauditory Cannals

Question 22

PA Axial Projection - Caldwell Method

Answer 22

• Forehead & nose on bucky
• OML Perpendicular
• MSP perpendicular
• CR – 15° caudad
• CP - Halfway between vertex and base of skull
  Petrous ridges in lower third of orbits
  Demonstrates superior orbital fissure

Question 23

AP Axial Projection - Towne method

Answer 23

• MSP perpendicular
• OML perpendicular
• Chin tucked – will need a sponge behind the head if the head is not touching the bucky
• CP – passes through 2” above (5 cm) EAMs
• CR - 30° caudad
• Dorsum sellae and posterior clinoid processes demonstrated within the foramen magnum

Question 24

What angle is required if the IOML was perpendicular (rather than OML) for the Towne method?

Answer 24

37 caudad

Question 25

If you see the posterior arch of C1 what positioning fault has been made?

Answer 25

***too much caudad angle or if the OML is pointed inferior instead of being perpendicular to the Bucky***

Question 26

Submentovertical Projection (SMV)Basal View or Schüller Method

Answer 26

- IOML parallel with plane of IR - MSP perpendicular - CP passes through EAM's - Do this image last

Question 27

why do you need to check if the patient has had a neck injury for a SMV?

Answer 27

not for trauma patients or patients with a neck injury

Question 28

Submentovertical Projection (SMV)Basal View or Schüller Method positioning criteria

Answer 28

- Odontoid process is demonstrated within the foramen magnum - Equal distance between mandibular condyles and edges of skull - TILT - Mandibular condyles anterior to petrous ridges - Mental protuberance superimposed on frontal bone

Question 29

what are Ruggles/Caldwell/Towne usually repeated for?

Answer 29

rotation and extension

Question 29

What are laterals usually repeated for?

Answer 29

rotation and tilt

Question 30

What are SMV's usually repeated for?

Answer 30

Extension and tilt