Indications for imaging
Trauma, sinusitis (See RCR guide) polyps, masses and tumours.
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Anatomy Demonstrated
Zygoma, maxilla, inferior orbital margin, inferior portion
of frontal bone, maxillary, ethmoid and frontal sinuses, nasal
spine and septum.
Facial Bones OM Anatomy
Meschan, I. 1955 An Atlas of Normal Radiographic Anatomy
Saunders, London
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Basic Patient Position
Dentures and oral jewellery should be removed.
The patient sits erect facing the bucky, midsagittal plane in
the midline of the film, coronal plane parallel to the film
interpupillary line parallel to the floor. The chin is raised to
bring the orbital meatal line at 45 degrees to the film.
In some centers the patient is imaged mouth open to demonstrate
the sphenoid sinuses.
Facial Bones OM Patient Position
Based on Movin & Karlsson 1975 Skeletal
projections for Diagnostic Radiology Lippincott
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Radiation protection
Direct lead rubber thyroid protection advisable.
A beam delineating cone / diaphragm will limit the area
irradiated reducing the scatter to the thyroid region.
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Central Ray
The horizontal central ray is centered in the midline of the
occiput so that the emergent ray exits the patient in the
midline at the level of the anterior nasal spine at the upper
border of the maxilla.
Note the projection requires an angle of 45 degrees between the
OM line and the central ray if the patient is unable to raise
the chin sufficiently then the central ray may need to be angled
caudally to maintain the 45 degree angle.
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Exposure Factors
| Kv |
mAS |
FFD (cm) |
Grid |
Focus |
AEC |
Cassette |
| 85 |
40 |
100 |
Yes |
Fine |
Yes |
24 x 30 cm |
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Evaluation of the Image
ID and anatomical markers must be present and correct in the
appropriate area of the film.
Optimal exposure should penetrate all the bone structures and
contrast should be low enough to visualise fully the bone and
soft tissue structures.
Limits of the examination, superiorly the frontal sinuses, laterally
the zygomatic arches and inferiorly the petrous bones.
The symmetric facial structures should be projected symmetrically
about the midline, the lower border of the maxillary sinuses
should be projected above the petrous bones.
Facial Bones OM Radiograph
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Related Projections
Skull PA 20
Skull Reverse Townes
Skull SMV
Skull Lateral
Facial Bones OM 30
Facial Bones Lateral
Nose Lateral
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Additional modalities
CT
MRI |
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