Lateral Lumbar is a radiography positioning projection of the Spine. Lateral recumbent, knees flexed, CR perpendicular to the iliac crest (L4-5) on a large IR. The centering point is located at the level of the iliac crest on a large IR (Bontrager calls this L4-5, Merrill's L4), or L3 on a small IR. The central ray is perpendicular to IR at the level of the iliac crest (L4-5) on a large IR, or L3 on a small IR, with a waist support (a wide pelvis and narrow thorax may need 5-8 degrees caudad, even with support). Image-quality criteria include all lumbar vertebrae L1-L5 clearly visualized, intervertebral disc spaces open symmetrically. A sample technique is 96 kVp with DR 28 or CR 56 mAs, at an SID of 40 inches (102 cm).
Anatomy demonstrated
- Lumbar vertebral bodies L1-L5.
- Intervertebral disc spaces.
- Lumbar spinous processes.
- Intervertebral foramina of the lumbar spine.
Patient preparation
- WARNING: with possible spinal injury or severe trauma, do not attempt to move the patient (Bontrager). The trauma lateral uses a horizontal beam.
- Verify patient identity using two identifiers.
- Remove jewelry, belt, and radiopaque objects.
- Lateral recumbent position, true lateral alignment.
- Hips and shoulders perpendicular to IR.
- Radiolucent support under the waist so the spine is parallel to the IR.
- Knees flexed for patient comfort.
Position & centering point
At the level of the iliac crest on a large IR (Bontrager calls this L4-5, Merrill's L4), or L3 on a small IR.
Central ray
Perpendicular to IR at the level of the iliac crest (L4-5) on a large IR, or L3 on a small IR, with a waist support (a wide pelvis and narrow thorax may need 5-8 degrees caudad, even with support).
Exposure / technique
- kVp
- 96
- mAs
- DR 28 / CR 56
- SID
- 40" (102 cm)
- Notes
- Knees flexed for patient comfort and stability. Bontrager prints 85 +/- 5 kV for digital systems; the sample below is from Merrill's chart. Sample technique: DR 28 / CR 56 mAs at 96 kVp, 40 in SID, for a 27 cm part (Merrill's sample chart). Adjust for your equipment.
kVp and mAs are sample values. Use caution when applying them in your department.
Image-quality criteria
- All lumbar vertebrae L1-L5 clearly visualized.
- Intervertebral disc spaces open symmetrically.
- Vertebral bodies superimposed without rotation.
- Spinous processes in profile.
- Spine parallel to the IR: intervertebral foramina and joint spaces open.
Common errors
- 1 Rotation: greater sciatic notches and posterior vertebral bodies not superimposed.
- 2 No waist support, so the spine sags and the joint spaces do not open.
- 3 CR not centered for the IR size misses mid-lumbar vertebrae.
Clinical indications
- Pathology of the lumbar vertebrae, including fractures and spondylolisthesis.
- Neoplastic processes and osteoporosis of the lumbar vertebrae.