Pediatric forearm (AP view)

The anteroposterior forearm view for pediatrics is one of two standard projections in the forearm series to assess the radius and ulna.

Indications

This view demonstrates the elbow joint in its natural anatomical position allowing for assessment of suspected dislocations or fractures and localizing foreign bodies within the forearm.

However, this view should not be considered when evaluating occult wrist or elbow injuries due to beam divergence. Beam divergence (Figure 1) at the edges of the image should be acknowledged when assessing anatomy ¹.

Patient position

• patient is seated alongside the table

• the fully extended forearm is supinated and kept in contact with the image receptor

• ensure all dorsal aspects of the forearm from wrist to elbow are kept in contact with the receptor

Technical factors

• anteroposterior 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 ²

  • 50-55 kVp

  • 2-4 mAs

• SID

  • 110 cm

• grid

  • no

Image technical evaluation

• the trochlea and capitellum can be seen in profile. 

• the wrist is in AP position, with minimal superimposition of the distal radius and ulna.

• the arm should be extended appropriately, evidenced by the radial head being seen in profile.

Lead shielding

Contact lead shielding is no longer recommended for any pediatric examination. Statements have been released by several radiological societies supporting an end to this practice ^3-6, with the most comprehensive guidance statement on this matter being in an 86-page joint report ⁷.

Please see your local department protocols for further clarification as they may differ from these recommendations.

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.

When changing from a lateral to an AP position, lowering the table height can help the patient extend their elbow joint depending on mobility.

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 ⁸.