cranium, facial bones, orbits, sinuses, nasal bones+ theory only Flashcards
(175 cards)
1
Q
What is the degree of difference between the OML
and IOML?
A
7 degrees
2
Q
What is the degree of difference between the OML
and GML?
A
8 degrees
3
Q
what is the CR for PA mandibular rami
A
perpendicular exiting the acanthion
4
Q
what structures are visualized on PA projection of ,and mandibular rami
A
Mandibular body (central part not
shown well) and rami
Medial/lateral displacement of
fractures of rami
5
Q
how is the patient positioned for PA Axial projection( theory only)
A
MSP and OML perpendicular to IR
6
Q
CR for PA axial mandible theory only projection
A
20 or 25 degrees cephalad
to exit at the acanthion
7
Q
what structures are visualized PA axial theory only projection
A
Mandibular body (central part not
shown well) and rami
Medial/lateral displacement of
fractures of rami
8
Q
Patient position for Axiolateral/axiolateral oblique-theory only
A
IPL perependicular to IR
Mouth closed teeth together
Ramus – true lateral
Body – rotate head 30 degrees
toward IR
Symphysis – rotate patient’s
head 45 degrees toward IR
9
Q
CR for Axiolateral/axiolateral oblique -theory only
A
25 degrees cephalad to
pass directly through the
mandibular region of
interest
If the shoulder will be
projected onto the
mandible:
Adjust MSP of skull with ~
15 degree angle and
adjust CR cephalic angle
to 10 degrees cephalad
10
Q
what structures are visualized in Axiolateral/axiolateral oblique
A
Structure that is parallel to IR
Ramus
Body
Symphysis
11
Q
patient position for SMV- submentovertical theory only projection
A
MSP perpendicular to IR
IOML as parallel to IR as
possible
12
Q
CR for SMV (Submentovertical)
A
Perpendicular to the
IOML and entering the
MSP of the throat at a
level approx. 1 inch
(2.5cm) posterior to
outer canthus
13
Q
what structures are visualized on SMV projection
A
Bilateral symmetric image of
the zygomatic arches free of
superimposed structures
14
Q
Patient position for Tangential projection of zygomatic arches
A
IOML as parallel to IR as
possible
Rotate MSP of head approx.
15 degrees toward side of
interest
Tilt top of head approx. 15
degrees away from side of
interest
15
Q
what is the CR for tangential projection of zygomatic arches
A
Perpendicular to IOML
and centered to
zygomatic arch at a
point approx. 1 inch
(2.5 cm) posterior to
the outer canthus
16
Q
what structures are visualized on tangential projection of zygomatic arches
A
Zygomatic arch free of
superimposition
Projection useful in patients
with depressed fractures or flat
cheekbones
17
Q
what is the patient position of AP Axial (modified Towne) of zygomatic arches
A
MSP and OML perpendicular
to IR
18
Q
CR for AP Axial (Modified Towne) -zygomatic arches
A
Entering the glabella
approx. 1 inch (2.5 cm)
above nasion at an
angle of 30 degrees
caudad
If the patient cannot
flex neck to get OML
perpendicular – adjust
IOML perpendicular and
angle 37 degrees
caudad
19
Q
what is the patient position for AP Axial projection for TMJs
A
MSP and OML perpendicular to
IR
20
Q
what is the CR for AP axial of the TMjs projection
A
Directed 35 degrees
caudad, centered midway
between TMJ’s and
entering at a point approx.
3 inch (7.6cm) above the
nasion
Open and closed mouth
projections
NOTE: open mouth should
not be attempted with
patients who have had a
recent injury
21
Q
structures for PA axial tmjs projection
A
Condyles of the mandible and
mandibular fossae of the temporal
bones
22
Q
patient position for Axiolateral TMJs projection
A
Seated upright or
semiprone
Center a point ½ inch
(1.3cm) anterior to EAM
to IR
Place head in lateral
position – affected side
closest to IR
MSP parallel to IR
IPL perpendicular to IR
After making exposure with
patient’s mouth closed,
change IR, then (unless
contraindicated) have the
patient open the mouth
widely
23
Q
CR for Axiolateral TMJs projection
A
Directed to
midpoint of IR at
angle of 25 or 30
degrees caudad
CR enters ½ inch
(1.3 cm) anterior
and 2 inches (5cm)
superior to upside
EAM
24
Q
structures for Axiolateral projection of TMJs
A
TMJ anterior to EAM
Condyle in mandibular
fossa in close-mouth
examination
Condyle inferior to articular
tubercle in open-mouth
examination if patient is
normal and able to open
mouth widely
25
PA axial caldwell-cranial bones
-OML perpendicular
-Centered @ nasion
-15 degrees caudad
-Petrous ridges in lower
1/3 of orbits
26
PA axial caldwell -facial bones
-OML perpendicular
-Centered @ nasion
-15 degree caudad
-Petrous ridges in
lower 1/3 of orbits
27
PA axial caldwell-sinuses
-OML perpendicular
-Centered at nasion
-Perpendicular CR
15 degree angle
between OML and CR
-Petrous ridges in
lower 1/3 of orbits
28
PA Axial Caldwell- orbits
-OML perpendicular
- centred @ nasion
-30 degrees caudad
-Petrous ridges below
inferior margin of
orbits
29
AP Axial Towne- cranial bones
-OML perpendicular
-Center @ 2 ½ inch above glabella,
passing through EAMs, exiting
foramen magnum
-30 degrees caudad
(OML perpendicular)
37 degrees caudad
(IOML perpendicular)
-- Dorsum sella within
foramen magnum
30
Parietoacanthial Waters-facial bone
-center at acanthion
-Perpendicular CR
-OML forms 37 degree
angle to plane of IR
-Petrous ridges below
floor of maxillary
sinus
31
Parietoacanthial waters-sinuses
-center at acanthion
-Perpendicular CR
-OML forms 37 degree
angle to plane of IR
-Petrous ridges below
floor of maxillary sinus
32
Parietoacanthial
Waters- nasal bones
-center at acanthion
-Perpendicular CR
-OML forms 37 degree
angle to plane of IR
-Petrous ridges below
floor of maxillary sinus
33
Parietoacanthial
Waters-orbits=modified waters
-center at acanthion
-Perpendicular CR
OML forms 50 degree
angle to plane of IR
-- Petrous ridges within
maxillary sinus
34
lateral-cranial bones
-perpendicular CR
-Center 32 inches superior to EAM
35
Lateral - facial bones
- perpendicular CR
-Entering lateral
surface of the
zygomatic bone
halfway between the
outer canthus and
EAM
36
Lateral -sinuses
-perpendicular CR
-Perpendicular to the bridge
of the nose, at a point ½
inch (1.3 cm) distal to the
nasion
37
lateral- orbits
-perpendicular CR
-Perpendicular through
the outer canthus
38
what side+ orientation IR is used for PA axial caldwell cranial bones
- medium IR + lengthwise
39
CR for PA Axial caldwell cranial bones
15 degrees caudad, exiting nasion
40
what is the patient position for PA Axial caldwell of cranial bones
-PA upright
-Nose= forehead against IR
-OML aligned perpendicular to IR
-check MSP is straight =no tilt or rotation
41
collimation for PA Axial caldwell projection of the cranial bones
includes vertex of skull, and lateral skull margins
42
breathing instructions for PA axial caldwell projection of cranial bones
-suspend
43
where can you look for rotation on a PA axial caldwell
lateral boarder of skull tpo lateral borders of orbits on each side
44
where to look for tilt on PA Axial caldwell
-look at petrous pyramids, to see if that are symmetrical
45
Where to look for OML/CR position on PA Axial caldwell
-too see if teh OML is aligned look to see if petrous pyramids are in the lower 1/3rd
46
what happens to petrous pyramids if we increase CR caudal angulation?
move further down
IE)15- 25 = they will move out of orbits
47
how do we fix the petrous pyramids being in the orbits, with perpendicular CR + OML perpendicular
correct by increasing CR caudal angel OR tipping head back
48
how do we fix the petrous pyramids being out of the orbits( below them)
corrects by decrease in CR caudal angle or tip head down
49
what IR= orientation is used for AP Axial Towne projection of the cranial bones
-medium IR lengthwise
50
what is the CR for AP Axial towne projection of the cranial bones
30 degrees caudad (if OML perpendicular); 37 degrees caudad (if IOML
perpendicular) – entering 2.5 inches above glabella, passing through EAM, exiting
foramen magnum
51
Patient position for AP axial towne projection of the cranial bones
AP upright
* Posterior head against IR
* Tuck chin to bring OML perpendicular to IR
* Adjust MSP straight (no tilt or rotation)
52
what is the collimation for the AP Axial townes projection of the cranial bones
* Include vertex of skull and occipital bone and lateral skull margins (1 inch
beyond skin line)
53
what are the breathing instruction for AP Axial townes projection of the cranial bones
suspend
54
on the AP Axial (Towne) – Cranial bones where do you look for rotation?
* Include vertex of skull and occipital bone and lateral skull margins (1 inch
beyond skin line)
55
on the AP Axial (Towne) – Cranial bones where do you look for tilt
– Symmetric petrous pyramids
56
on the AP Axial (Towne) – Cranial bones where do you look for OML/CR postion?
Dorsum sellae and posterior clinoid processes visible within foramen
magnum
57
what error has occurred if the dorsum sella projects above the foramen
magnum
-insufficient caudal angulation= increase CR caudal angulation OROr tuck patient’s chin down to place OML
perpendicular to IR
58
what error has occurred if the anterior arch of C1 is laying in the
foramen magnum?
-excessive CR angulation, fix=less CR caudal angulation is
required OR extend patient’s neck to place OML
perpendicular to IR
59
what is the IR size+orientation for Lateral projection of cranial bones
medium IR, crosswise
60
what is the CR for lateral projection of the cranial bones
: Perpendicular; entering 2 inches superior to EAM
61
what is the patient position for the lateral projection of the cranial bones
* Upright – L or R lateral
* IPL perpendicular to IR (no tilt)
* MSP parallel to IR (no rotation)
* IOML perpendicular to front edge of IR (chin lifted slightly)
62
what is the collimation for the lateral projection of the cranial bones.
Include frontal bone, vertex of skull, and occipital bone (1 inch beyond
skin lin)
63
what is the breathing instructions for lateral projection of the cranial bones.
suspend
64
where to look for rotation on the lateral projection of the cranial bones
– alignment/mis-alignment anteriorly-posteriorly
Superimposed orbital roofs and greater wings of sphenoid
Superimposed mastoid regions and EAM
Superimposed TMJs
Sella turcica in profile
65
where to look for tilt on the lateral projection of the cranial bones
alignment/mis-alignment superiorly-inferiorly
Superimposed orbital roofs and greater wings of sphenoid
Superimposed mastoid regions and EAM
Superimposed TMJs
Sella turcica in profile
66
IR size + orientation for a PA Axial caldwell projection for the facial bones
Medium IR, lengthwise
67
what is the CR for A PA axial caldwell projection of the facial bones
15 degrees caudad, exiting the nasion
68
what is the patient position for a PA axial, caldwell projection of the facial bones
* PA upright
* Nose + forehead against IR
* OML aligned perpendicular to IR
* Check MSP is straight (no rotation or tilt)
69
what is the collimation fro a PA axial, caldwell projection of the facial bones
Include lateral margins of skull, half of forehead, and
upper incisors
70
what is the breathing instructions for PA Axial projection of the facial bones
suspend breathing
71
where do you look for rotation for PA Axial caldwell projection of facial bones
– lateral border of skull to lateral borders of orbits on each side, saem as cranial bones
72
where do you look for tilt for PA Axial caldwell projection of facial bones
– symmetric petrous pyramids
73
where do you look for OML/ CR position for PA Axial caldwell projection of facial bones
petrous pyramids lying in lower 1/3 of orbits
74
what is the IR size+ orientation for Parietoacanthial (wateres) projection of the facial bones
medium IR and lengthwise
75
What is the CR fro Parietoacanthial (waters) projection of the facial bones
: Perpendicular to exit the acanthion
76
what is the patient position for parietoacanthial (Waters) – Facial bones
* PA upright
* Adjust chin until MML perpendicular to IR (OML @ 37 degree
angle to IR)
* Check MSP is straight (no rotation or tilt)
77
what is the collimation for a parietoacanthial (waters) projection of the facial bones
* Include lateral margins of skull, half of forehead, and upper
incisors
78
breathing instructions for waters projection of facial bones
suspend
79
how to recognize rotation on waters projection of the facial bones
– distances between lateral borders of skull and orbits equal
on both sides
80
how to recognize tilit on waters projection of the facial bones
MSP of head aligned with long axis of collimated field
81
how to recognize OML/ MML position on waters projection of the facial bones
– petrous ridges projected immediately below
maxillary sinuses
82
lateral facial bones IR size+ orientation
medium IR, lengthwise
83
what is the CR for lateral projection of the facial bones
: Perpendicular; entering lateral surface of zygomatic bone;
halfway between outer canthus and EAM
84
patient position for lateral projection of the facial bones
Position:
* Upright – L or R lateral
* IPL perpendicular to IR (no tilt)
* MSP parallel to IR (no rotation)
* IOML perpendicular to front edge of IR (chin lifted slightly)
85
what is the collimation for lateral projection of the facial bones
* Include about half of frontal bone/frontal sinus to EAM, all
facial bones (but not necessary to include all of the mandible)
86
where to look for rotation on the lateral projection of the facial bones
– alignment/mis-alignment anteriorly-posteriorly
Superimposed orbital roofs (same as cranial bones lateral)
Sella turcica in profile (same as cranial bones lateral)
WANT Almost perfectly superimposed mandibular rami (almost
superimposed due to magnification)
87
where to look for tilt on the lateral projection of the facial bones
Tilt – alignment/mis-alignment superiorly-inferiorly
Superimposed orbital roofs (same as cranial bones lateral)
Sella turcica in profile (same as cranial bones lateral)
WANT Almost perfectly superimposed mandibular rami (almost
superimposed due to magnification)
88
why do we use a straight CR for sinuses
CLEARLY shows air fluid levels MORE precisely then angled CR
89
what is necessary to demonstrate air, fluid + soft tissue for the sinuses
Balance of contrast + brightness = NECESSARY
90
what is the IR size and orientation for PA Axial caldwell sinuses
medium IR, lengthwise
91
what is the CR for the PA Axial caldwell projection of the sinuses
perpendicular, exiting the nasion
92
what is the patient positioning for PA Axial caldwell projection of the sinuses
* PA upright
* Adjust chin until OML forms 15 degree angle to horizontal CR
* Check MSP is straight (no rotation or tilt)
93
what is the collimation for a PA Axial caldwell projection of the sinuses
Include lateral margins of skull, half of forehead, and upper incisors
94
what is the breathing instructions for PA Axial caldwell projection of the sinuses
Suspend
95
how to detect rotation on a PA axial caldwell projection of the sinuses
Equal distance between lateral border of the skull and lateral border
of the orbits (same as cranial and facial bones, although a bit different wording)
96
how to detect tilt on a PA axial caldwell projection of the sinuses
– symmetric petrous pyramids (same as cranial and facial bones)
97
how to detect OML position on a PA axial caldwell projection of the sinuses
petrous pyramids lying in lower 1/3 of orbits
frontal sinuses lying above frontonasal suture and anterior ethmoidal air
cells lying above petrous ridges (only sinuses)
Any corrections that need to be made to position of petrous ridges within orbits – only move patient’s
head, never move CR angle (always perpendicular CR)
98
IR size and orientation for parietoacanthial waters projection of the sinuses
Medium IR lengthwise
99
what is the CR for the parietoacanthial waters projection of the sinuses
Perpendicular to exit the acanthion
100
what is the patient position for the Parietoacanthial Waters projection of the sinuses
Position:
* PA upright
* Adjust chin until MML perpendicular to IR (OML @ 37 degree angle to IR)
* Check MSP is straight (no rotation or tilt)
101
what is the collimation for the parietoacanthial waters projection of the sinuses
* Include lateral margins of skull, half of forehead, and upper incisors
102
what are the breathing instructions for the parietoacanthial waters projections
suspend
103
how to detect rotation on Parietoacanthial Waters projection of the sinuses
Rotation –
– distances between lateral borders of skull and orbits equal on both sides (same
as facial bones)
– orbits and maxillary sinuses symmetric on each side (only for sinuses)
104
how to detect tilt on Parietoacanthial Waters projection of the sinuses
how to detect rotation on Parietoacanthial Waters projection of the sinuses
105
what should the OML position be for parietoacanthial waters projection of teh sinuses
* OML position – Petrous pyramids lying immediately inferior to floor of maxillary
sinuses
106
IR size + orientation for the Open mouth Waters projection of the sinuses
medium IR-lengthwise
107
CR for the Open mouth Waters projection of the sinuses
perpendicular to exit acanthion
108
what is the patient position for the nmnb
* PA upright
* Adjust chin until MML perpendicular to IR (OML @ 37 degree angle to IR)
* After positioning the MML, ask patient to open mouth by dropping jaw
* Check MSP is straight (no rotation or tilt)
109
what is the collimation for Open mouth Waters projection of the sinuses
Include lateral margins of skull, half of forehead, and upper incisors (could
collimate tighter than regular Waters)
110
what is the breathing instructions for the Open mouth Waters projection of the sinuses
suspend breathing
111
how to detect rotation on the Open mouth Waters projection of the sinuses
distances between lateral borders of skull and orbits equal on both sides
orbits and maxillary sinuses symmetric on each side
112
how to detect tilt on the Open mouth Waters projection of the sinuses
MSP of head aligned with long axis of collimated field
orbits and maxillary sinuses symmetric on each side
113
how to detect OML position on the Open mouth Waters projection of the sinuses
Petrous pyramids lying immediately inferior to floor of maxillary sinuses
Sphenoidal sinus projected through open mouth – only for open mouth waters
114
what is the IR size + orientation for the lateral sinuses
medium lengthwise
115
what is the CR for the lateral projection of the sinuses
Horizontal, entering ½-1 inch (1.3-2.5cm posterior to outer canthus)
116
what is the patient position for the projection of the lateral sinuses
Upright – L or R lateral
* IPL perpendicular to IR (no tilt)
* MSP parallel to IR (no rotation)
117
what is the collimation for the lateral sinuses
* Include about half of frontal bone/frontal sinus to EAM, all facial bones (but
not necessary to include all of the mandible)
118
what is the breathing instructions for the lateral sinuses
suspend breathing
119
how to detect rotation on the lateral projection of the sinuses
alignment/mis-alignment anteriorly-posteriorly
Superimposed orbital roofs
Sella turcica in profile
Superimposed mandibular rami
120
how to detect tilt on the lateral projection of the sinuses
alignment/mis-alignment superiorly-inferiorly
Superimposed orbital roofs
Sella turcica in profile
Superimposed mandibular rami
121
IR size + orientation for parietoacanthial waters
medium lengthwise
122
what is the CR for the Parietoacanthial Waters of the nasal bones
Perpendicular to exit the acanthion
123
what is the patient position for the Parietoacanthial Waters of the nasal bones
* PA upright
* Adjust chin until MML perpendicular to IR (OML @ 37 degree angle to IR)
* Check MSP is straight (no rotation or tilt)
124
what is the collimation for the Parietoacanthial Waters of the nasal bones
limation:
* Collimate longitudinally to include frontal sinus, and transversely to mid-orbit
125
how to detect rotation on the Parietoacanthial Waters projection of the nasal bones
– distances between lateral borders of skull and orbits equal on both sides (if you
can see them)
– MSP of head aligned with long axis of collimated field (more helpful)
126
how to detect tilt on parietoacanthial waters projection of the nasal bones
MSP of head aligned with long axis of collimated field
127
how to detect OML/MML position on parietoacanthial waters projection of the nasal bones
– petrous ridges projected immediately below maxillary sinuses
128
IR orientation and size for lateral nasal bones
medium lengthwise
129
what is the CR for the lateral projection of the nasal bones
: Perpendicular, 0.5 inch (1.25 cm) inferior to nasion
130
what is the patient position for the lateral nasal bones
Upright – L or R lateral
* IPL perpendicular to IR (no tilt)
* MSP parallel to IR (no rotation)
131
what is the collimation for the projection of the lateral nasal bones
Include frontal sinus longitudinally; transversely include within 1 inch of nose
skin line
132
breathing instructions for lateral nasal bones
suspend breathing
133
is a grid used for the lateral projection of the nasal bones
NOOOOO, a grid is NOT used
134
whats the main reason to do projections of the orbits
too look, and find/spot foreign bodies
135
how can you reduce geometric shaprness
- reducing OID – use free cassette instead of table/upright bucky to reduce magnification
- Using small undamaged focal spot
➢-SID that is as long as is consistent with exposure factors required
136
is table bucky the best choice when imaging orbits
NOOOOOO,– use free cassette instead of table or upright
bucky to reduce chance of artifacts from bucky on image
137
what is the CR for the PA Axial projection of the orbits
30 degrees caudad directed through center of orbits
138
what is the patient position for the PA axial caldwell projection of the orbits
PA upright
* Nose + forehead against IR
* OML aligned perpendicular to IR
* Check MSP is perpendicular (no rotation or tilt)
139
what is the collimation for the PA Axial caldwell projection of the orbits
* Include 1 inch beyond all sides of the orbit
140
how to detect tilt/ rotation on a PA Axial caldwell projection of the orbits
Symmetric visualization of the orbits
141
where do we want the petrous pyramids on the PA Axial projection of the orbist
Petrous pyramid lying below orbital shadows
142
IR size + orientation for the lateral projection of the orbits
mediusm IR, crosswise
143
what is the CR for the lateral projection of the orbits
Perpendicular through outer canthus
144
what is the patient position for the lateral projection of the orbits
Position:
* Upright – L or R lateral
* IPL perpendicular to IR (no tilt)
* MSP parallel to IR (no rotation)
* IOML perpendicular to front edge of IR
145
what is the collimation for the lateral projection of the orbits
Include 1 inch beyond all sides of the orbit
146
what is the breathing instructions for the lateral orbits
suspend
147
where to look for rotation/tilt on the lateral projection of the orbits
superimposed orbital roofs- TIS/RAP
148
What should be at the center of the exposure field for the PA axial Caldwell projections?
ethmoid sinuses
149
What positioning error occurred if the posterior arch is visualized within the foramen magnum?
Excessive chin tuck/excessive caudal CR angle
150
What should be centered within the foramen magnum on an AP axial Townes of the cranial bones?
Dorsum sellae
151
Where should the petrous ridges be demonstrated for all PA axial Caldwell projections?
Through the lower 1/3 of the orbits
152
What positioning error occured if the petrous ridges are projected below the orbits and the OML is perpendicular?
Excessive caudal CR angle
153
Where should the petrous ridges be demonstrated on a Waters projection if the MML is perpendicular to the IR?
Below the maxillary sinuses
154
What error occurred on a lateral projection if the greater wings of the sphenoid are misaligned anteriorly/posteriorly?
Head is rotated
155
How should the CR be angled for a PA axial Caldwell projection of the cranial bones if the superior orbital fissures are of primary interest?
20-25 degrees caudad
156
What could the technologist do for an AP Axial Towne projection if the patient is not able to line up the OML perpendicular to the IR?
Align IOML perpendicular and angle CR 37 degrees caudad
157
What line should be perpendicular to the IR for a lateral projection of the cranial bones?
IPL
158
What angle does the OML form with IR for a parietoacanthial Waters projection of the facial bones?
37 degrees
159
What is the ideal patient position when imaging the sinuses?
Upright
160
How should the CR be directed for the PA axial Caldwell projection of the sinuses?
Perpendicular, exiting the nasion
161
What is the central ray for the lateral projection of the sinuses?
Entering 0.5-1 inch (1.3 to 2.5 cm) posterior to outer canthus
162
Where should the petrous ridges be demonstrated on an image of a PA axial Caldwell?
Through the lower 1/3 of the orbits
163
What positioning error occurred if the petrous ridges were demonstrated at the superior orbital margins and the patient's OML was perpendicular to the IR?
Insufficient caudal CR angle
164
What structures should be demonstrated within the foramen magnum on an AP axial Towne projection of the cranial bones?
Dorsum sella and posterior clinoids
165
What positioning error occurred if the posterior arch of C1 was demonstrated within the foramen magnum on an AP axial Towne projection, and the CR was angled 30 degrees?
Excessive chin tuck
166
What positioning error occurred on a parietoacanthial Waters projection of the sinuses if the petrous ridges are demonstrated below the maxillary sinuses?
No error has occurred
167
What positioning error has occurred on a lateral projection of the facial bones if the greater wings of the sphenoid are misaligned inferiorly/superiorly?
Tilt
168
What is the CR for the lateral projection of the nasal bones?
Perpendicular to 0.5 inch (1.25cm) inferior to nasion
169
How can image quality be improved when imaging the orbits for localization of foreign bodies?
Increase SID
170
What is the central ray for the PA axial projection of the orbits?
30 degrees caudad through center of the orbits
171
What is the central ray for the axiolateral oblique projection of the mandible?
25 degrees cephalad through the mandibular region of interest
172
How should the patient be positioned for the axiolateral mandible if the body is of primary interest?
Rotate head 30 degrees towards IR
173
What projection could be done to obtain a bilaterally symmetric image of the zygomatic arches, free of superimposed structures?
Submentovertical or AP axial (Modified Towne)
174
What is the CR for the AP axial projection of the TMJ's?
35 degrees caudad
175
What angle should the OML form with the IR for a Modified Waters projection of the orbits?
50 degrees
