9/20- Lumbar Spine Positioning

What SID is commonly used for routine lumbar-spine projections?

40 inches.

What patient position is commonly used for a routine AP lumbar spine?

Supine.

What CR angulation is used for a routine AP lumbar spine?

Perpendicular to the IR.

Where is the CR centered for an AP lumbar spine when the entire lumbosacral region is included?

At the MSP at the level of the iliac crest.

Where is the CR centered when imaging the lumbar spine only?

Approximately 1 to 1½ inches above the iliac crest at the MSP.

Why are the hips and knees flexed for an AP lumbar spine?

To reduce lumbar lordosis and place the lumbar spine more parallel to the IR.

What respiration instruction is used for an AP lumbar spine?

Suspend respiration at the end of expiration.

What anatomy should be included on an AP lumbar-spine image?

Approximately T12 through the sacrum.

What finding indicates minimal rotation on an AP lumbar-spine image?

The spinous processes are centered and the pedicles and SI joints appear approximately symmetric.

What should happen to the intervertebral disk spaces on a properly positioned AP lumbar image?

They should appear as open as possible.

What is the primary purpose of an AP oblique lumbar-spine projection?

To demonstrate the lumbar zygapophyseal joints.

What secondary radiographic appearance is demonstrated on lumbar obliques?

The Scotty dog.

How much is the patient generally rotated for an AP oblique lumbar spine?

Approximately 45° for L1-L4.

Which lumbar zygapophyseal joints are demonstrated on posterior obliques?

The joints closest to the IR.

Which lumbar zygapophyseal joints are demonstrated in an RPO position?

The right zygapophyseal joints.

Which lumbar zygapophyseal joints are demonstrated in an LPO position?

The left zygapophyseal joints.

What CR angulation is used for a routine AP oblique lumbar spine?

Perpendicular to the IR.

Where is the CR centered for a lumbar AP oblique?

Approximately 2 inches medial to the elevated ASIS, near the level of the iliac crest.

What respiration instruction is used for lumbar obliques?

Suspend respiration at the end of expiration.

What anatomy should be demonstrated on a lumbar oblique image?

The zygapophyseal joints and Scotty dogs.

What does an open zygapophyseal joint indicate on a lumbar oblique?

Appropriate patient rotation for the joint being examined.

What patient position is commonly used for a lateral lumbar spine?

Lateral recumbent with the knees flexed.

Why are the knees flexed for a lateral lumbar spine?

To improve stability and help reduce lumbar lordosis.

What CR angulation is normally used for a lateral lumbar spine?

Perpendicular if the lumbar spine is horizontal.

Where is the CR centered for a lateral lumbar spine?

Near the level of the iliac crest for the lumbosacral region or slightly superior for lumbar spine only.

Which structures are best demonstrated on a lateral lumbar spine?

Vertebral bodies, intervertebral disk spaces, and intervertebral foramina.

Which projection best demonstrates lumbar intervertebral foramina?

The lateral projection.

What finding helps confirm a true lateral lumbar position?

The greater sciatic notches and posterior vertebral body margins are closely superimposed.

What happens to the intervertebral foramina on a properly positioned lateral lumbar image?

They should appear open.

What respiration instruction is used for a lateral lumbar spine?

Suspend respiration at the end of expiration.

What is the purpose of the lateral L5-S1 spot projection?

To demonstrate the L5-S1 intervertebral disk space and lumbosacral junction.

Where is the CR centered for a lateral L5-S1 spot projection?

Approximately 1½ inches inferior to the iliac crest and about 2 inches posterior to the ASIS.

What CR angulation may be used for a lateral L5-S1 spot projection?

Approximately 5° to 8° caudad when needed to open the L5-S1 disk space.

Why may a caudal CR angle be used for the lateral L5-S1 spot?

To direct the beam more nearly parallel to the angled L5-S1 disk space.

How should the field be collimated for a lateral L5-S1 spot projection?

Tightly to the lumbosacral junction.

What anatomy must be clearly visualized on a lateral L5-S1 spot image?

The L5-S1 disk space and adjacent portions of L5 and S1.

What CR direction is used for an AP axial L5-S1 projection?

Cephalad.

What CR angle is commonly used for an AP axial L5-S1 projection on an average male patient?

Approximately 30° cephalad.

What CR angle is commonly used for an AP axial L5-S1 projection on an average female patient?

Approximately 35° cephalad.

What CR direction may be used for a lateral L5-S1 spot projection?

Perpendicular if the disk space is adequately aligned, or approximately 5–8° caudad when needed to open the L5-S1 disk space.