Paediatric chest (PA erect view)

The posteroanterior erect chest view is often performed in older paediatric patients; when the patient is able to co-operate with sitting or standing erect. This chest view examines the lungs, bony thoracic cavity, mediastinum and great vessels.

Indications

The PA erect view is often chosen over the AP erect view in paediatric imaging due to the decreased radiation dose to radiosensitive organs: developing breast, sternum and thyroid ¹. The choice to perform a PA erect or AP erect chest view will depend on the radiographer’s judgement of the patient’s cooperative and understanding ability.

Patient position

• patient is sitting or standing erect facing the detector
• head is straight and chin raised out of the field of view
• shoulders touching the detector to ensure no rotation ¹
  • ideally shoulders rolled anteriorly to remove scapulae off chest wall; however, if the child struggles with this position, they can ‘hug the detector/bucky’

Technical factors

• posteroanterior projection
• suspended inspiration
• centring point
  • the level of the 7^th thoracic vertebra; approximately at the inferior angle of the scapulae
• collimation ²
  • superior to the 3rd cervical vertebrae
  • inferior to the thoracolumbar junction
  • lateral to the skin margins
  • it is advised not to collimate too tightly at the apices as breathing may cause the apices to move superiorly
• orientation
  • portrait
• detector size
  • 24 cm x 30 cm or 35 cm x 43 cm depending on the patient’s size
• exposure ³
  • 60-80 kVp
  • 1-2 mAs
• SID
  • 110 cm
• grid
  • no

Image technical evaluation

• entire lung fields should be visible; post-processing collimation is not advisable in paediatric imaging (if it is exposed it should be examined)
  • this is particularly important if the clinical indications query a foreign body as demonstrating the abdomen will also be useful in the diagnosis
  • it is also important because other bones accidentally included in the field may be injured, e.g. fractured humerus in NAI
• full inspiratory effort ⁴
  • ensure 8 visible posterior ribs in children aged 0-3 years old
  • ensure 9 posterior ribs in children aged 3-7 years old
  • ensure 10 posterior ribs in children aged 7 years old and above

Rotation

• the clavicles lie on the same horizontal plane and anterior ribs are of equal length ¹
  • ​due to ossification centres in children, the medial ends of clavicles are difficult to visualise; therefore measuring the medial ends of the clavicle to the spinous process is not advised
• the head of clavicles to lie at the level between T2 and T4 ⁴
• medial ends of the ribs are an equal distance to the centre of the spine 

Lead shielding

Contact lead shielding is no longer recommended for any paediatric examination, multiple radiological societies have released statements supporting the cessation of this practice ^5-8 the most comprehensive guidance statement on this matter (86 pages) is a joint report found at this citation ⁹.
Please see your local department protocols for further clarification as they may differ from these recommendations.

Practical points

As the paediatric patient is facing the detector, there may be a tendency for the child to want to turn around and see what is happening behind him/her. Therefore, radiographers must ensure that the child understands that no motion is required. This may be done in the form of a game or through explanations if they are old enough to understand. Some examples of specialised communication techniques to gain co-operation from the child include:

• “lets play dead fish!”
• “freeze!”
• “you have to breathe in like you are about to blow out a birthday candle!”
• “take a big sniff now”

It may also be difficult to observe the patient breathing in when they are in a PA position; therefore practising with the child before exposing and observing the child's shoulders carefully can give an indication of inspiration.