Indications for imaging
Trauma, congenital abnormalities.
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Anatomy Demonstrated
Sacro iliac joints.
Sacro Iliac Joints Anatomy
Meschan, I. 1955 An Atlas of Normal Radiographic Anatomy
Saunders, London
|
Basic Patient Position
The patient lies prone on the table midline aligned to the
midline of the table coronal plane parallel to the table, a
support under the ankles to aid comfort.
Sacro Iliac Joints PA Patient Position
Meschan, I. 1955 An Atlas of Normal Radiographic Anatomy
Saunders, London
|
Radiation protection
There are many local rules for gonad protection however the
following should be taken into account. The 28 day rule should
be applied for female patients.
In males direct lead rubber gonad protection can be applied at
all times
On small patients the omission of a grid will reduced the
exposure.
|
Central Ray
The central ray is angles 20 degrees caudally and centered in
the midline at the level of the posterior superior iliac spines,
or the largest sacral prominence if palpable.
A sorter than normal FFD may help demonstrate the joints because
of the greater divergent angle of the beam.
Exposure is made on suspended respiration.
|
Exposure Factors
Kv |
mAS |
FFD (cm) |
Grid |
Focus |
AEC |
Cassette |
85 |
60 |
100 (75)( |
Yes |
Broad |
Yes |
24 x 30 cm |
|
Evaluation of the Image
ID and markers must be present and correct in the appropriate
area of the film
Evidence of collimation on four sides equally around the
centering point.
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, the iliac bone surrounding the
joint on all sides.
the lumbar sacral articulation should be projected open, the
sacroiliac joints will appear open or nearly open.
Sacro Iliac Joints PA Radiograph
|
Related Projections
Sacrum AP
Lumbar sacral articulation Lateral.
Sacro iliac joint obliques.
|
Additional modalities
CT
MRI
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