The scoliosis posteroanterior/anteroposterior (PA/AP) view allows for visualizing the thoracic and lumbar vertebral bodies of interest.
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Indications
This projection is used in determining scoliosis in patients and allows for the severity of lateral spinal curvature to be assessed 1.
Patient position
patient erect (or supine depending on the protocol)
if the patient is erect, arms by sides and equal weight on both feet
ensure the patient aligned centrally to the image receptor
ensure rotation of hips and shoulders is reduced as much as possible (some rotation inherent to scoliosis may be inevitable)
ensure at least 3-5 cm of iliac crests are present on the radiograph
Technical Factors
anteroposterior or posteroanterior projection
suspended expiration
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centering point
dependent on area of interest, patient height and detector size
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collimation
dependent on orthopedic preference and imaging modality
superiorly to include all vertebrae of interest (may be at C7)
inferiorly to include sacral region (may be at S1 or level of femoral heads)
lateral collimation sufficient to include all of spinal curvature
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orientation
portrait
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detector size
most likely a sticthed series
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exposure
80-95 kVp (digital)
40-60 mAs
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SID
100 cm - 150 cm
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grid
yes
Image technical evaluation
area of scoliosis should be visible with evidence of iliac crests inferiorly
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no patient rotation
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rotated vertebrae may be distinguished from scoliotic vertebrae in that:
rotated vertebral bodies will have their long axes straight and
scoliotic vertebral bodies will have a lateral deviation
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long axis of the spine should be straight along the long axis of the IR
bony margins and trabecular patterns should both be clearly visible in thoracic and lumbar vertebrae
Practical points
PA projections should be considered over the AP projection for the reduced dose to radiosensitive organs situated anteriorly
a compensatory wedge filter may be appropriate to achieve an even density throughout the image 1