What is X-RAY LUMBAR SPINE AP LAT?

AP:
The lumbar spine anteroposterior or posteroanterior view images the lumbar spine in its anatomical position. The lumbar spine generally consists of five vertebrae (see: lumbosacral transitional vertebra).

LAT:
The lumbar spine lateral view images the lumbar spine which generally consists of five vertebrae (see: lumbosacral transitional vertebra).

Indications

AP:
This projection is utilized in many imaging contexts including trauma, postoperatively, and for chronic conditions. Ideally, spinal imaging should be taken erect in the non-trauma setting to give a functional overview of the lumbar spine. Otherwise, patients with a suspected spinal injury must remain in the supine position without any movement.

LAT:
This projection shows an orthogonal view of the AP/PA view and is utilized in many imaging contexts including trauma, postoperatively, and for chronic conditions. This view is also ideal in characterizing spinal alignment.

Note: Ideally, spinal imaging should be taken erect in the non-trauma setting to give a functional overview of the lumbar spine. Otherwise, patients with a suspected spinal injury must remain in the supine position without any movement.

Patient position

AP:

• the patient is erect or supine, depending on clinical history
• in the supine projection, hands are placed by the patient's side
• if performing erect, position the patient in the PA position; this has numerous advantages including reduced dose to the gonadal region and utilization of beam divergence; arms can be placed by the side, or the handlebars of the erect Bucky can be held for patient stability. The weight-bearing PA view can be called the Ferguson technique.

LAT:

• the patient is positioned erect, supine, or lateral recumbent, depending on clinical history
• in the lateral decubitus position, position the patient so that the humeri are extended 90 degrees to the thorax, with the elbows flexed so that the forearms are parallel to the thorax. Spinal curvature in the AP projection will determine if a right lateral or a left lateral is performed.
• when implementing the horizontal beam technique, ensure the distal upper limbs are not overlying the region of interest. Ask the patient to cross their arms over their upper thorax, or to extend them in a similar position to that achieved in the lateral decubitus position

Technical factors

AP:

• Anteroposterior projection
• Suspended expiration (for a uniform density)
• Centering point
  • the level of the iliac crests at the MSP
  • the central ray is perpendicular to the image receptor
• Collimation
  • superiorly to include the T12/L1 junction
  • inferior to include the sacral region
  • lateral to include the transverse processes and sacroiliac joints
• Orientation
  • portrait
• Detector Size
  • 35 cm x 43 cm
• Exposure
  • 70-80 kVp
  • 40-60 mAs
• SID
  • 110 cm
• Grid
  • Yes (ensure the correct grid is selected if using focused grids)

LAT:

• Lateral projection
• Expiration (to minimize superimposition of the diaphragm over the upper lumbar spine)
• Centering point
  • the level of the iliac crest
  • coronal centering point is directly over the lumbar vertebra, which corresponds to the posterior third of the abdomen
  • the central ray is perpendicular to the image receptor
• Collimation
  • superiorly to include the T12/L1
  • inferior to include the sacrum
  • anterior to include the anterior border of the lumbar vertebral bodies
  • posterior to include all elements of the posterior column, particularly the spinous processes
• Orientation
  • portrait
• Detector Size
  • 35 cm x 43 cm
• Exposure
  • 70-80 kVp
  • 60-80 mAs
• SID
  • 110 cm
• Grid
  • Yes (ensure the correct grid is selected if using focused grids)