Lateral Thoracic is a radiography positioning projection of the Spine. Lateral recumbent, CR perpendicular to T7. Breathing technique. The centering point is located T7, 3-4 inches below the jugular notch, with the posterior half of the thorax centered to the midline. The central ray is perpendicular to IR at T7 level with a waist support; otherwise 10-15 degrees cephalad. Image-quality criteria include thoracic bodies, disc spaces and foramina shown; T1-T3 are not well seen, intervertebral disc spaces open symmetrically. A sample technique is 90 kVp with DR 25 or CR 50 mAs, at an SID of 40 inches (102 cm).
Anatomy demonstrated
- Thoracic vertebral bodies (T1-T3 obscured by the shoulders).
- Intervertebral disc spaces.
- Intervertebral foramina of the thoracic 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 and radiopaque objects from the area being imaged.
- Lateral recumbent position, true lateral alignment.
- Hips and shoulders perpendicular to table.
- Arms raised at right angles to the body, out of the field.
- Radiolucent support under the waist so the spine is parallel to the IR.
- Head on a pillow, hips and knees flexed, with support between the knees.
Position & centering point
T7, 3-4 inches below the jugular notch, with the posterior half of the thorax centered to the midline.
Central ray
Perpendicular to IR at T7 level with a waist support; otherwise 10-15 degrees cephalad.
Exposure / technique
- kVp
- 90
- mAs
- DR 25 / CR 50
- SID
- 40" (102 cm)
- Notes
- Use breathing technique to blur ribs. Slow, even breathing. Sample technique: DR 25 / CR 50 mAs at 90 kVp, 40 in SID, for a 33 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
- Thoracic bodies, disc spaces and foramina shown; T1-T3 are not well seen.
- Intervertebral disc spaces open symmetrically.
- Vertebral bodies superimposed without rotation.
- Posterior aspects of the vertebral bodies superimposed (no rotation).
- Posterior ribs separated by less than 1/2 inch (no rotation).
Common errors
- 1 Rotation shifts vertebral bodies creating illusion of offset.
- 2 Insufficient breathing blur leaves rib superimposition.
- 3 Arms not raised to right angles to the body.
- 4 CR not at T7 misses mid-thoracic structures.
Clinical indications
- Pathology such as compression fractures or subluxation.
- Evaluation of kyphotic deformity.