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Department
of Podiatry
Views
& Projections of the Foot
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A
projection is the x-ray tube's 'eye view' or direction of
the central ray of radiation.
A
view is the finished radiograph and is the opposite to a projection.
Where the X-ray film presses against the foot.
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For example,
consider the most commonly taken X-ray of the foot, the AP view/projection
(weightbearing), whereby the foot is weightbearing on the ground,
standing on the X-ray film. The beam of the X-ray machine is directed
downwards through the foot (dorsal to plantar), but not completely
vertically. The beam is angled at 15° away from the subject to
better visualise joints in the midfoot.
The projection
in this case is called an Anteroposterior (AP) projection. This
is because the direction of the beam moves through the foot more anteriorly
(ie. distally) before travelling posteriorly (ie. proximally) in the
foot. Think the projector of a movie camera. Where the beam comes
from, and where it goes to, in anatomical terminology.
The view
in this case is described as Posteroanterior (PA) view. The posterior
(or more proximal and plantar) part of the foot is in contact with
the X-ray film.
Scroll
down this page for the following views and projections: anterior-posterior
(AP) (weightbearing), medial oblique, lateral (weightbearing), axial
sesamoid projection, Harris and Beath (coalition view), lateral oblique
and axial calcaneal (non-weightbearing).
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Anterior-Posterior
(AP) or dorso-plantar projection (weightbearing):
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Head of x-ray angled 15° from vertical
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Central ray aimed at Navicular
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Bones visualized: Phalanges, Metatarsal, Navicular and
medial Cuneiform.
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Joints visualized: Midtarsal Jt, Lisfranc Jt, MTP Jts, IP
Jts
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Medial
Oblique
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Head angled at 15°, 30°, 45° or 60°
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Central Ray aimed at 1st cuneiform
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Bones visualized: The cuboid and navicular are clearly seen,
but the cuneiforms are superimposed upon each other. All other
bones distal to the midfoot are clearly visualized.
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Joints visualized: Talonavicular, navicularcuneiform, cuboidnavicular,
cuboid-lateral cuneiform, calcaneocuboid & Lisfranc's
joint. All MTPJ's.
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Lateral
View weightbearing
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Head angled 90° from vertical
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Central ray aimed at cuneiform
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Bones visualized: talus, calcaneus, cuboid, navicular, medial
cuneiform, 1st metatarsal.
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Joints visualized: Midtarsal Jt, Subtalar Jt, 1st metatarsal-cuneiform,
navicular-1st cuneiform.
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Axial
Sesamoid Projection
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Head angled perpendicular to the ground
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Central ray aimed at midline of foot
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Bones visualized: Sesamoids and Sagittal plane relationship
of metatarsal heads
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Joint visualized: Sesamoid-1st metatarsal
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Harris
and Beath (Coalition View)
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Head angle - depends on declination of posterior STJ
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Central ray aimed at STJ
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Bones visualized- Med and Lat malleoli, talus, calcaneus
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Joint visualized- STJ, ankle JT.
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Lateral
Oblique
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Head angled at 45° from vertical
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Central Ray aimed at cuboid
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Bones visualized: ...
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Joint visualized: ...
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Axial
Calcaneal non-weightbearing
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Head angled 45° to the horizontal
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Central ray aimed at posterior calcaneus
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Bones visualized- plantar-posterior aspect of the calcaneus
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Joints visualized - No joints visualized
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NB:
For full evaluation of the patient, multiple projections are required.
A full 'Foot' series of X-rays generally involves an anteroposterior,
medial oblique and lateral film of the foot in question.
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