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1. Adjust your X-ray
control to the highest KVP and MA available.
2. Adjust your exposure
time according to the schedule on the following page (based
on Dr. Goos' graduated, ISI Wicor-400 or Lanex Regular screens
and Clear Image OGA film). Density must be adequate
to clearly visualize the lambdoidal suture in the back of
the skull. This suture is your "density barometer". Increase/decrease
the time as necessary.
3. Adjust the collimator
and cassette holder for the 8x10 horizontal format.
4. Seat (position)
and shield the patient in a natural posture. Duplicate their
natural "plumb-line" (center of shoulder to center of hip)
and cervical posture. Observe the relationship of the ear
hole to this plumb-line and duplicate.
5. The patient must
answer "NO" to the following four questions:
(A). Do you feel as
if you are stretched up?
(B). Do you feel as
if you are slouched?
(C). Do you feel as
if you are leaning back?
(D). Do you feel as
if you are leaning forward?
6. Bring the cassette
in contact with the side ear support or as close to the
patient as possible.
7. For systems NOT
utilizing the Dr. Goos graduated intensifying screens or filtration
at the beam source, adjust the soft tissue shield according
to the figure 1. Block type shields must be flush with the
edge of the cassette with the cassette and shield moved anteriorly/posteriorly
as an ssembly keeping the tip of the nose 1" in from the edge.
Use a 12" ruler to
align the tip of the nose with a mark 1" in from the edge
of the cassette.
8. Position the patient's
Frankfort Plane (ear piece to orbitale, most inferior surface
of the orbit) Parallel With The Floor.
9. Guide the patient
into the desired occlusal and lip position and expose.
10. For proper density
and resolution, process in automatic processors at a CONFIRMED
83°F (28.3°C) for 5.5 minutes using only IMAGING
SYSTEMS' AUTOCHEM PRE- MIXED or KODAK RP X-OMAT developer
and fixer or in manual tanks at 68°F for 5 minutes using
Kodak GBX solutions (fix for a maximum of 4 minutes).
Suggested Exposure
Guidelines for Cephalograms using
Dr. Goos/ISI Wicor-400
Rare Earth/Lanex Regular Intensifying Screens/Clear Image
OGA Film
Focal Spot to Mid-sagittal
plane: 60 in
Exposure Time in impulses
(60 impulses in 1 sec.)
|
KVP
|
90
|
90
|
80
|
80
|
70
|
70
|
70
|
65
|
65
|
60
|
55
|
|
MA
|
15
|
10
|
15
|
10
|
15
|
10
|
7
|
15
|
10
|
10
|
7
|
|
Child
|
13
|
17
|
16
|
21
|
24
|
30
|
36
|
24
|
36
|
53
|
70
|
|
Adult
|
16
|
21
|
19
|
25
|
36
|
51
|
60
|
48
|
60
|
55
|
90
|
|
Large Adult
|
19
|
25
|
22
|
29
|
48
|
60
|
75
|
60
|
75
|
78
|
2.3 Sec
|
* Use of Kodak TMAT-H
film will reduce the above exposure time by 1/2 but will result
in grainer appearance
Conversion Chart for
Fractions/Decimals to Impulses
|
Fractions
|
Decimals
|
Impluses
|
|
1/60
|
0.00
|
1
|
|
1/20
|
0.05
|
3
|
|
1/15
|
0.05
|
4
|
|
1/10
|
0.10
|
6
|
|
2/15
|
0.10
|
8
|
|
3/20
|
0.15
|
9
|
|
1/5
|
0.20
|
12
|
|
1/4
|
0.25
|
15
|
|
3/10
|
0.30
|
18
|
|
7/20
|
0.35
|
21
|
|
2/5
|
0.40
|
24
|
|
9//20
|
0.45
|
27
|
|
1/2
|
0.50
|
30
|
|
11/20
|
0.55
|
33
|
|
3/5
|
0.60
|
36
|
|
13/20
|
0.65
|
39
|
|
7/10
|
0.70
|
42
|
|
3/4
|
0.75
|
45
|
|
4/5
|
0.80
|
48
|
|
17/20
|
0.85
|
51
|
|
9/10
|
0.90
|
54
|
|
19/20
|
0.95
|
57
|
|
1
|
1.00
|
60
|
|
1-1/4
|
1.25
|
75
|
|
1-1/2
|
1.50
|
90
|
CEPHALOMETRIC QUALITY
ASSURANCE CHECKLIST
1. Absence of Hypo
(wavy, flat black matte appearance).
2. Lead Letters must
be in the image (the word/letter LEFT/L if the left cheek
is against the cassette)
3. Absence of a lead
apron, necklace and/or ear rings, etc. in the image.
4. Lambdoidal suture
must be clearly evident (your "density barometer").
5. Frankfort Plane
must be parallel with the floor.
6. Adequate soft tissue
profile.
7. Single inferior
border of the mandible indicating either mid-sagittal plane
symmetry or facial asymmetry.
8. "Natural" lordotic
curve (George's line).
9. 8-10mm spacing between
cranial base and the spinous process of CI.
10. 6-8mm nasopharynx
airway in the area of the posterior-superior aspect of the
soft palate.
What else to look for
on a LATERAL CEPHALOGRAM / LATERAL CERVICAL SPINE
1. Pharyngeal airway
in area of soft palate.
2. Spatial relationship
of C1 to cranial base.
3. Cervical spine contours.
4. Elevation of hyoid
bone.
5. Anti-gonial notching
(aka. bone deposition at the gonial angle).
6. Ossification of
stylohyoid ligament.
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