Indications for imaging
Trauma
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Anatomy Demonstrated
Occiput, foramen magnum, pituitary fossa, zygomatic arches.
Skull Reverse Townes Anatomy
Meschan, I. 1955 An Atlas of Normal Radiographic Anatomy
Saunders, London
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Basic Patient Position
The patient sits erect facing the bucky, midsagittal plane in
the midline of the film, interpupillary line parallel to
the floor. The chin is lowered 30 degrees from the PA position
to bring the orbital meatal line at 60 degrees to the film.
Skull Reverse Townes 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 centered through the occiput in
the midline at the level of the external auditary meati.
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Exposure Factors
| Kv |
mAS |
FFD (cm) |
Grid |
Focus |
AEC |
Cassette |
| 85 |
60 |
100 |
Yes |
Broad |
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.
Compared with a typical FO 30 Townes projection the skull is
projected without geometric distortion which normally elongates
the occiput.
Limits of the examination, superiorly the vertex, inferiorly the
petrous bones, laterally the skull margins.
The symmetrical structures should be projected evenly either side
of the midline. The posterior clinoid processes should be
visible in the round foramen magnum.
Skull Reverse Townes Radiograph
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Related Projections
Skull PA 20
Skull SMV
Skulll Lateral
Facial Bones OM
Facial Bones OM 30
Facial Bones Lateral
Nose Lateral
Mandible PA
Mandible oblique
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Additional modalities
CT
MRI |
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