Thoracic spine (lateral view)

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The thoracic spine lateral view images the thoracic spine, which consists of twelve vertebrae.

Indications

This projection is utilized in many imaging contexts including trauma, postoperatively, and for chronic conditions. It can help to visualize any compression fractures, subluxation or kyphosis, and is used in conjunction with the AP view to complete a thoracic spine series.

Patient position

  • the patient is erect, supine or lateral decubitus depending on clinical history
    • ideally, spinal imaging should be taken erect in the setting of non-trauma to give a functional overview of the thoracic spine
    • all imaging of patients with a suspected spinal injury must occur in the supine position without moving the patient
    • the lateral projection requires the upper limbs to be removed from the path of the direct x-ray beam, minimizing the superimposition of the proximal humeri over the thoracic vertebrae
    • in all variations of positioning, the humeri are extended 90º to the thorax, with the elbows flexed so that the forearms are parallel to the thorax

Technical factors

  • lateral projection
  • suspended expiration (or breathing technique if possible) 
  • centering point
    • the level of the 7th thoracic vertebra, which correlates to the inferior border of the scapula, centered directly over the thoracic spine (most commonly equates to the posterior third of the thorax) 
    • the central ray is perpendicular to the image receptor 
  • collimation
    • superiorly to include the C7/T1 junction
    • inferiorly to include the T12/L1 junction
    • anterior and posterior to include the anterior margin of all thoracic vertebrae and posterior to include the posterior column elements. 
  • orientation  
    • portrait
  • detector size
    • 35 cm x 43 cm 
  • exposure
    • 80-100  kVp
    • 40-80 mAs 
  • SID
    • 110 cm
  • grid
    • yes (ensure the correct grid is selected if using focused grids)

Image technical evaluation

The entire thoracic spine should be visible from T1 to T12:

  • intervertebral joints and neural foramen are open, with the superimposition of the posterior spinous processes and posterior rib articulation indicating a true lateral has been achieved
  • adequate image penetration and image contrast is evident by clear visualization of thoracic vertebral bodies, with both trabecular and cortical bone demonstrated
  • visualization of the upper thoracic spine is often difficult given the patient thickness at this region. If clinical concern for injury in this area is strong, the cervical spine: swimmer's lateral view can be included, or referral to CT can be made

Practical points

  • the three-column concept of thoracolumbar spinal fractures is of particular importance when assessing this image for pathology
  • exaggerated thoracic kyphosis can mean the field of view is wide and can include the majority of the anterior thorax; be aware of this when collimating and choosing the coronal centering point
  • horizontal beam imaging can produce unwanted image artefact. Attempt to remove all potential artefacts including excessive sheets/blankets and monitoring devices (if safe)
  • when moving the patient's arm be aware of any concurrent shoulder girdle injuries; if the patient is unable to extend the humeri 90º to the thorax, place an immobilization wedge over the thorax and ask them to extend their arms over this equipment; this will help to decrease superimposition whilst maintaining a level of patient comfort
  • in order to achieve a true lateral projection, a caudal or cephalic tube angulation may be required, depending on spine curvature
  • utilizing the handle commonly used for erect lateral chest radiographs can provide support for patients in this position, whilst simultaneously removing the humeri away from the upper thoracic region