NUCCA X-Ray Analysis
Analysis Equipment
 Cephalometer
 Circumscale
 Relatoscope
 Vertex square
Lateral Film
PURPOSE:
To obtain the S line of
the atlas
 To tell if the atlas has
gone inferior or superior
To determine where to
take the Nasium
Lateral Film Analysis
 S Line
 Place a dot where the posterior arch of atlas meets the
lateral mass
 Place a second dot about 1/3 down along the length of the
posterior arch of atlas
*Note that because of how the Nasium film is taken, if the S line does
not go through the mastoid markers, you must move the line
up/down in a parallel fashion so that it does. This way it will be
taken at the proper angle.
S-Line
Nasium Film
PURPOSE:
 To determine atlas laterality
 To determine upper and
lower angle to determine
the basic type
 To determine APL, A/O,
C/A, Ang, At, OD, BC, Sp
 To calculate the height
vector
 To determine if C2 spinous
rotation is present (torque)
Nasium Film
 Atlas Plane Line (APL)
 Place a dot on the lower border of the posterior arch
where it crosses the lateral masses on each side of atlas
Nasium Film
 Central Skull Line (CSL)
 Mark the squamous
suture on each side of
the head
 Mark the vertex of the
head on each side
 The CSL will only be
determine using the
area between these
two points
Nasium Film
 CSL Continued
 Use the Cephalometer to match like points on either side
of the head in order to determine the center of the skull
 Mark a lower pivot point intersecting the APL
 Mark an upper pivot point at the top of the skull
Nasium Film
 CSL Continued
 Starting with the lower pivot
point, make your way up the
skull finding like points with
the cephalometer by keeping
the lower pivot point in the
slot. The line should match
up with the two pivot points
 Then make your way down
with the upper pivot point
 Repeat
 If the line shifts, you have
the wrong pivot points and
need to redo
 Once you have the best
points, mark the CSL with a
solid line
Nasium Film
 Atlas Laterality (At)
 To find laterality measure the side of the acute angle
between the CSL and APL
Nasium Film
 Head Tilt
 To find the head
tilt, measure the
angle between
the true vertical
and the CSL
Nasium Film
 Condylar Circle
 Mark the outer 1/3 of the surface of the occipital condyles
 Using the circumscale, find the best fit circle = c
 If it comes out to ½, round down
Nasium Film
 Axial Circle
 Place a dot (A) on the most lateral
aspect of the superior surface of C2
on each side
 Also place a dot (B) on the medial
aspect of the superior surface of C2
on each side
 Connect those dots on each side
 From the medial dots, place
another dot (C) 3/32’’ down
perpendicularly from that line
 Use A and C to find the best fit
circle for axis = a
 If it comes out to ½, round up
A
B
B A
Condylar and Axial Circles
Nasium Film
 Odontoid Center (OD)
 Mark the center of the Odontoid
Nasium
 C2 Body Center (BC)
 Using the dots on the lateral aspect of the superior surface of
C2, place the center of a protractor on each dot and scribe and
arcs above and below
 Use a straight edge to connect the two intersections
 Draw a small line down the center in the middle of the
intersections
Nasium Film
 BC Continued
 Use the relatoscope that corresponds to the condylar circle
 Square up atlas so that the horizontal lines of the
relatoscope are parallel to the APL and the lateral masses
are boxed in equally
 Determine the degrees (if any) the body center line is off
from the 0 mark on relatoscope
 If BC is on the same vertical line as the 0 mark then BC = At
Nasium Film
 C2 Spinous (SP)
 Mark the inferior bifurcation of C2 spinous
 Use the relatoscope again to compare position of C2
spinous to atlas like you did with BC
 The lateral film can help you locate its position if its hard to
see by comparing where it is on the lateral film in relation to
the posterior arch of atlas
OD/BC/SP
Nasium Film
 Fixed Point
 Mark the lateral
aspects of the
zygapophyseal
joints of C7
 Determine the
midpoint
 Mark a point (D)
between BC and SP
if not on same
vertical line
 Connect the
midpoint of C7 to D
dot
D
Nasium Film
 Lower Angle
 Measure the
acute angle
between the
APL and the
fixed point line
Nasium Film
 Height Vector Components




PL
A/BC
C/A
Ang
Height Vector Calculations
 PL
 Use a true horizontal and move it up/down until it matches up
where the APL crosses the ramus of the jaw on the side
opposite of laterality and draw a small straight reference line
on the side of laterality
 Measure how far above or below the APL is compared to that
true horizontal
 If APL is lower by:
 1/16th “  - ¼”
 2/16th “  - ¾”
 3/16th “  - 1’’
 If APL is higher by:
 1/16th “  + ¼”
 2/16th “  + ¾”
 3/16th “  + 1’’
PL
Height Vector Calculations
 A/BC
 Compare the amount of atlas laterality due to atlas side
slip (ss) versus head tilt (ht)
 If ht ≥ ss, then A/BC = -1/2 ht but only up to amount of
laterality
 If ht < ss, then A/BC = -1/2 ht
 If ht = 0 or if it does not contribute to laterality, then A/BC
=0
 If BC > At like in a Type I with a large lower angle, then
A/BC = +1 for the first degree extra
Height Vector Calculations
 C/A
 This is equal to + (a-c)⁄2
Height Vector Calculations
 Ang
 Take the difference of At – lower angle
 For contralateral acute angles
 + ¼” for every 1° difference
 For ipsilateral acute angles
 - ¼” for every 1° difference
 If the lower angle is less than or equal to atlas laterality,
then Ang = 0
Height Vector Calculation Practice
 At R2
 OD R2
3c
 BC R2
+ 4/16th
 SP R2
8a
L6
PL = + 1 ¼
A/BC = 0
C/A = + 2 ½
Ang = + 1
_______________
+4¾
Height Vector Calculation Practice
 At R4 (RS)
 OD R4
3c
 BC R1
+ 2/16th
 SP R4
10a
L4
PL = + ¾
A/BC = - 1 ½
C/A = + 3 ½
Ang = 0
_______________
+2¾
Height Vector Calculation Practice
 At R4 (R4)
3c
 OD R4
 BC R0
 SP R4
5 ½a
L0
PL = 0
A/BC = - 2
C/A = + 1 ½
Ang = 0
_______________
-½
Vertex Film
PURPOSE:
 To determine C1 rotation
 To determine
anterior/posterior vector
Vertex Film
 Mark the anterior and posterior aspect of both lateral masses
 Mark the center of the transverse foramen and draw a line
connecting the two points
 Use the vertex square to box in atlas using the lateral masses to
make sure all those points/lines are parallel
 If the line of the transverse foramen isn’t parallel to the lateral
masses, use the lateral masses
 Measure the angle between the true vertical line and the
transverse foramen or lateral mass line on the side of laterality
 If the angle is acute = anterior rotation
 If the angle is obtuse = posterior rotation
 Vector = 1” for every 1° anterior or posterior
Vertex