Paediatric Chest Projections

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There is no difference in the diagnostic value of an antero-posterior (AP) projection compared to the postero-anterior (PA) projection of the chest in a child less than 4 years of age as the thoracic cage is essentially cylindrical in young children and magnification of mediastinal organs is insignificant (Blickman, J.G. (1994) Pediatric Radiology: The Requisites. Mosby, London). However, the AP projection is associated with a higher radiation dose to the developing breast, sternum and thyroid, and radiographers should take this into consideration when choosing the radiographic projection. In children under 4 years of age, the AP projection is often preferred due to ease of positioning and immobilisation. Young children like to see what is going on around them and positioning for an AP projection allows the child to watch the radiographer. A disadvantage of the AP projection is the likelihood of lordosis.

Antero-Posterior AP (Supine)

The patient is positioned supine with the median sagittal plane at 90° to the image receptor. A 15° foam pad is placed under the upper chest and shoulders to prevent lordosis. The chin is raised and the arms are flexed and held on either side of the head to prevent rotation. Sandbags and lead rubber are placed over the hips and legs to provide immobilisation of the legs or alternatively, the legs may be held at the knees by another radiographer or guardian. The primary beam should be centred to the area of interest thereby ensuring that effective collimation can be applied and dose reduced.

Antero-Posterior AP (Erect)

This projection can be performed with the patient standing or seated erect. For younger children, correct positioning and immobilisation are easier to maintain with the child seated. The patient is positioned initially with the posterior aspect of the chest in contact with a cassette. A 15° foam pad is then placed behind the upper chest and shoulders to prevent lordosis. The chin is raised and the arms are flexed and held on either side of the head by another radiographer or guardian to prevent rotation.The primary beam is centred to the middle of the area of interest and collimated to within the area of the cassette. Devices often used for this view are the "Fuller Chair" or "Pig O Stat".

Postero-Anterior PA (Erect)

This projection can be performed with the patient standing or seated. The patient is positioned with the anterior aspect of the chest in contact with a cassette and their arms around it. Both shoulders should touch the cassette to ensure that there is no rotation. The cassette is positioned to include both apices and the patient’s chin is rested on the cassette top. It is often easier for a young child to maintain this position rather than the more traditional position of the hands being placed on the back of the hips. However, if you are satisfied that the child will maintain the adult position then this should be used as it is more likely to help clear the scapulae away from the chest. The primary beam is centred to the middle of the area of interest and collimated to within the area of the cassette.

Lateral

Lateral chest radiography is often easier to perform on young children if they are seated. The child sits or stands with the side under investigation closest to an appropriately sized cassette. The cassette is positioned to include the whole of the chest. The patient’s chin is raised and the arms are flexed at the elbow and held on either side of the head by a suitably protected radiographer or guardian to prevent rotation. The primary beam is centred to the middle of the area of interest and collimated to within the area of the cassette


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