Lumbar Spine AP Oblique - RPO/LPO

Patient/part position for a Lumbar Spine - AP Oblique:

• recumbent or upright

• use same position as AP

• 45-degree posterior oblique position

Where is the central ray placed for a Lumbar Spine - AP Oblique?

• perpendicular to IR

• enters 2” medial to the elevated ASIS and 1-1.5” above the iliac crest (L3)

What is the radiation field for a Lumbar Spine - AP Oblique?

• 9 × 12” on the collimator for 10 × 12” IR

• 9 × 14” on the collimator for 14 × 17” IR

The AP Oblique view of the lumbar spine is particularly effective in demonstrating the:

zygapophyseal joints (facet joints) (articular facets) also called the "Scottie dog"

To visualize the right zygapophyseal joints in the lumbar spine, you would position the patient in a:

Right Posterior Oblique (RPO) position

Which side of interest is closest to the IR for a Lumbar Spine - AP Oblique?

• the right side of the patient is closest to the IR (RPO)

• The left side of the patient is closest to the IR (LPO)

What happened when the joint is not well seen, and the pedicle is anterior on the vertebral body?

the patient was not rotated enough

What happened when the joint is not well seen, and the pedicle is posterior on the vertebral body?

the patient was rotated too much

The ear on the “Scottie dog” represents:

the superior articular process

The nose on the “Scottie dog” represents:

the transverse process

The eye on the “Scottie dog” represents:

the pedicle

The front leg on the “Scottie dog” represents:

the inferior articular process

The tail on the “Scottie dog” represents:

the superior articular process of opposite side

The body on the “Scottie dog” represents:

lamina and spinous process

The back leg on the “Scottie dog” represents:

the inferior articular process of opposite side

The AP Lumbar Oblique (RPO/LPO) projection primarily visualizes the:

zygapophyseal joint closest to IR

The PA Lumbar Oblique (RAO/LAO) projection primarily visualizes the:

zygapophyseal joint farthest from IR