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بسم الله الرحمن الرحیم

Computer TomographyTechnique

Lecture 7:CT scan Vertebrals

September, 2012

Prepared by:

Behzad OmmaniMaster of Medical Engineering

Instructor Radiology Group

The Lumbar Spine

The two commonest reasons for imaging the lumbar spine are:

Lumbar disc disease, most commonly at L5/S1 and L4/L5;

Spinal stenosis, i.e. narrowing of either or both the spinal canal and lateral recesses

Lumbar

Patient position :

• Supine, Both arms should be raised above the head. This is the planning scan and is usually an anteroposterior (AP) view and lateral.

Start position : Zero to symphysis pubis

End position : Commence 35 cm

Lumbar

• Slice thickness 3-5 mm• Table increment 3-5 mm• Algorithm Standard• Kilovoltage 120-140 kV• mAs per slice 250-400 mAs• Scan field of view 48 cm• Display field of view 15 cm• Window width (WW) 500/1500• Window level (WL) 60/250

Lumbar Protocol

Lumbar Disc

• From the lateral scan projection radiograph, plan three axial sections through each disc space, from L5/S1 up to L1/L2, with the middle section passing through the middle of and parallel to each disc space.

• The axial scans should be 5 mm in thickness and separated using a table increment of 10 mm

Lumbar Stenosis

Lumbar Stenosis

• MR imaging should always be used to investigate cervical disc disease but, due to the lack of signal from bone, it is often very difficult to assess the degree of encroachment on cervical nerve roots from osteophyte formation within the intervertebral foramen.

Cervical

Patient position :

• Supine, Both arms should be raised above the head. This is the planning scan and is usually an anteroposterior (AP) view and lateral.

Start position : Zero to 5 cm above orbitomeatal baseline

End position : Length, 25 cm

Cervical Spine

• Axial scans (helical)• Slice thickness 1-3 mm• Table pitch 1-1.5• Algorithm Standard• Kilovoltage 120 kV• mAs per slice 200-400 mAs• Scan field of view 25 cm• Display field of view 15 cm• Window width 500/1500• Window level 60/250

Cervical Spine Protocol

postnasal space scan

Patient position :

• Supine with head in head cushion on table top• Lateral scan projection radiograph is optional

• Start position Skull base• End position : Epiglottis• Gantry angle : Parallel to infraorbital meatal line

• Slice thickness 5 mm• Table increment 5 mm• Kilovoltage 120 kV• mAs per slice 250 mAs• Algorithm Soft/standard• Scan field of view 25 cm• Display field of view 22 cm• Window width 400• Window level 20

Protocol for postnasal space scan