Positioning of the L-Spine, SI joints, Sacrum/Coccyx, & Scoliosis

What is the technique for the AP lumbar spine?

75 kVp at 30 mAs

What is the technique for the oblique lumbar spine?

80 kVp at 40 mAs

What is the technique for the lateral lumbar spine?

85-90 kVp at 50 mAs

What is the IR size/orientation for the L-spine?

14×17 LW, collimate down to 10×17

What is the IR size/orientation for the L5/S1 lateral spot?

10×12 LW

Where is the CR for the AP and lateral L-spine views?

At the crest

Where is the CR for the oblique L-spine?

At crest, and 2” medial to upside ASIS

Where is the CR for the L5/S1 lateral spot?

1 ½ inches inferior to the crest and 2 inches posterior to the ASIS

What should you always be sure to use for a L-spine?

• Waist support/sponge

• Lead blocker

What should you do if you’re not using a waist support for the L-spine?

Use a 5-8 degree caudal angle

What is the SID for the L-spine?

40 inch

What is the breathing for the L-spine?

Suspend respiration on expiration

What is the positioning for an AP lumbar spine?

• 14×17 IR and collimate down side to side (10×17), ensure to include both SI joints

• Ensure knees are bent

• Suspend on expiration

• Put marker approximately 5 inches from center

What is the positioning for the RPO/LPO lumbar spine?

• 45 degree obliques

• Arms across/knee bent

• CR at crest and 2 inches medial to upside ASIS

• Ensure hips and shoulder are in same plane

If the pedicle on the LPO/RPO oblique spine is demonstrated posteriorly on the vertebral body, what positioning error do you have?

Overrotation

If the pedicle on the LPO/RPO oblique spine is demonstrated anteriorly on the vertebral body, what positioning error do you have?

Underrotation

What does the RPO lumbar spine demonstrate?

Downside Z-joint

What does the LPO lumbar spine demonstrate?

Left zygapophyseal joint

What is the positioning for a left lateral L-spine?

• 14×17 LW; CR at crest

• Ensure patient in true lateral; go back 1-2 inches from MCP

• Left marker on anterior side of film

• Suspend respiration on expiration (gets costophrenic angles of lung out of way)

• Use sponge/lead blocker

What does the left lateral L-spine demonstrate?

Intervertebral foramina

What is the positioning of the L5/S1 lateral spot?

• 10×12 LW; slight collimation

• CR 1 ½ inches inferior to iliac crest and 2 inches posterior to ASIS

• If no sponge under side then use 5-8 degree caudal tube angle

• Use lead strip

What is the positioning for the lateral flexion and extension (spinal fusion series)?

• 24×17 LW; direct CR to fusion site or if unknown, place lower edge of IR 1-2 inches below iliac crest

• Ensure true lateral; cock-the-box if necessary

• Exipiration

• Hyperflexion: ask pt to assume fetal position (bend forward) and draw legs up as far as possible

• Hyperextension: ask pt to move torso and legs posterior as far as possible to hyperextend long axis of body

• No rotation of pelvis or thorax; 2 exposures

Why would you do the lateral flexion and extension (spinal fusion series)?

For assessment of mobility at spinal fusion site (pelvis must remain stationary)

What is the positioning for the AP right and left bending (scoliosis series)?

• 14×17 LW; keep collimation open

• Place bottom edge of IR 1-2 inches below iliac crest

• Arms out of way, knees bend, hold hips and ask patient to bend laterally as far as possible

• 2 exposures

Why would you do the AP right and left bending (scoliosis series)?

To see tangle of motion of vertebral column

What is the positioning for the AP axial L5-S1 (Ferguson)?

• 10×12 IR; 30-35 degree cephalic angle; line up tube and film 1st then float tabletop (33” - 34'“ SID plus angle = 40” SID)

• Cr is midline at level of ASIS, put sponge under knees for comfort

Why would you do the AP axial L5-S1 (Ferguson)?

TO see pathology of L5/S1 and the SI joints

What is the technique for the SI joints?

70-75 kVp at 24-32 mAs

What is the IR size/orientation for the SI joints?

10×12 LW

Where is the CR for the AP axial view of the SI joints?

2'“ below level of ASIS

Where is the CR for the posterior oblique views for the SI joints?

1” medial to upside ASIS

What is the SID for the SI joints?

40 inch (33” SID with angle should be approximately 40”)

What is the breathing for the SI joints?

Suspend respiration

What is the positioning for the AP axial- sacroiliac joint?

• 10×12 LW; 30-35 degree cephalic angle

• CR to midline approximately 2” below the level of ASIS

• Align tube 1st, then center tabletop

What is the positioning for the RPO & LPO obliques-sacroiliac joint?

• No tube angle, rotate body into 25-30 degree posterior obliques; direct CR 1 inch medial to upside ASIS

• Demonstrations upside SI joint. (LPO shows right SI joint), use left marker for left joint

• Can use angle sponge for obliques

What is the technique for the AP sacrum/coccyx?

65 kVp at 30 mAs

What is the technique for the lateral sacrum/coccyx?

85 kVp at 50 mAs

What is the IR size/orientation for the AP axial sacrum and lateral sacrum?

10×12 LW

What is the IR size/orientation for the AP axial coccyx?

10×12 LW, be sure to collimate down

Where is the CR for the AP axial sacrum and AP axial coccyx?

2” below the level of the ASIS

Where is the CR for the lateral sacrum/coccyx?

Place top of IR just below the crest and center 3-4 inches posterior to ASIS

What is the SID for the sacrum/coccyx?

40 inch

What is the breathing for the sacrum/coccyx?

Suspend respiration

Should you shield for the sacrum/coccyx?

Typically just males not females

What is the positioning for the AP axial sacrum?

• 15 degree cephalic angle; CR 2” below level of ASIS or midway between symphysis pubis and ASIS at MSP

• Right marker

• Bend knees slightly for patient comfort

What is the positioning for the AP axial coccyx?

• 10 degree caudal angle; CR 2’ below level of ASIS

• 7×7 collimation; be sure not to clip marker

What is the positioning for the left lateral coccyx?

• 10×12 IR; CR perpendicular to IR directed 3-4 inches posterior to ASIS

• Ensure no rotation of thorax or pelvis exists

• If clipped coccyx then 3-4 inches posterior and down 2” from ASIS

• Can use lead blocker

What is the technique for the AP scoliosis series?

75 kVp at 30-35 mAs

What is the technique for the lateral scoliosis series?

85-90 kVp at 40-50 mAs

What is the IR size/orientation for the scoliosis series?

14×17 LW Bucky (or use special cassette and IR holder)

Where is the CR for the standing scoliosis series?

Bottom of IR is placed 1-2 inches below crest, and must include at least T4

What is the SID for the standing scoliosis series?

40 inch

What is the breathing for the standing scoliosis series?

Expiration

How should you prep the pt for the standing scoliosis series?

• Take shoes off

• Use breast shielding for females

What is the positioning for the AP or (PA) scoliosis?

• 14×17 LW; place bottom of IR approximately 2” below crest and include T4

• CR perpendicular to IR

• Shoes off

• Expiration

• AP reduces OID but increases dose to breast and thyroid

• PA increases OID but reduces dose to breast and thyroid

What is the positioning for the lateral scoliosis?

• Bottom of IR is placed 1-2” below crest (include T4)

• CR perpendicular to IR and MCP, go back 1-2 inches from midline

• Ensure no rotation of thorax or pelvis, arms up out of way

• Expiration