Paediatric forearm (PA view)

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The posteroanterior forearm view for pediatrics is one of two modified trauma projections in the forearm series, examining the radius and ulna.

Indications

This view is ideal for patients who are unable to move their arm as per the standard forearm positioning technique but require assessment of suspected radius and/or ulna dislocations or fractures. This shows a PA view of the radius and lateral view of the ulna.

Patient position

  • patient is seated alongside the table
  • with 90° elbow flexion, the palmar aspect of the forearm from wrist to elbow are kept in contact with the receptor, ensuring the same horizontal plane (see Figure 1)

Technical factors

  • posteroanterior projection
  • centering point
    • mid forearm region
  • collimation
    • distal to the wrist joint 
    • proximal to elbow joint
  • orientation  
    • portrait
  • detector size
    • 24 cm x 30 cm
  • exposure
    • 50-55 kVp
    • 1.6-2 mAs
  • SID
    • 110 cm
  • grid
    • no

Image technical evaluation

  • the elbow joint is in true lateral position
  • the wrist joint is in PA position with little to no superimposition

Practical points

Preparing the room beforehand (setting up the detector, exposure and preparing lead gowns) is extremely beneficial for forearm imaging as young children may begin to cry the moment their affected arm is brought away from their body.

If immediately abducting the patient's arm on to an elevated tabletop is challenging, begin with the arm adducted and rested on a lowered tabletop. Reassure the patient that their forearm will not be touched or moved, then slowly begin to raise the tabletop. Encourage the patient to focus on abducting their unaffected shoulder joint until all aspects of their arm are in the same horizontal plane.

Immobilization techniques

To prevent malrotation/motion artifact in the radiograph, parental holding at the proximal half of the child’s arm and distal part of the hand may be required. Other alternative methods such as distraction techniques may be ideal to avoid scattered radiation to parents and staff .