Indications for imaging
Trauma, But see RCR recommendations.
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Anatomy Demonstrated
Frontal bone, orbits, frontal and ethmoid sinuses
Skull PA 20 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 lowered
to bring the orbital meatal line at 90 degrees to the film.
Skull PA 20 Patient Position
Based on Movin & Karlsson 1975 Skeletal
projections for Diagnostic Radiology Lippincott
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Radiation protection
Avoid irradiation of the thyroid region, direct lead rubber
protection my be used.
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Central Ray
The horizontal central ray is angled 20 degrees caudally and
centred in the midline of the occiput so that the exit ray
emerges in the midline at the level of the glabella.
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Exposure Factors
| Kv |
mAS |
FFD (cm) |
Grid |
Focus |
AEC |
Cassette |
| 85 |
50 |
100 |
Yes |
Broad |
Yes |
18 x 24 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 vertex, inferiorly the
base of the skull, lateraly the skull margins.
The symetrical structures should be projected evenly either side
of the midline,
The lower borders of the orbits should be projected immediately
above the petrous ridges.
Skull PA 20 Radiograph
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Related Projections
Skull Reverse Townes
Skull SMV
Skulll Lateral
Facial Bones OM
Facial Bones OM 30
Facial Bones Lateral
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Additional modalities
CT
MRI
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