Chest (PA view)

Chest: PA view is the most common radiological investigation in the emergency department ¹. The PA view examines the lungs, bony thoracic cavity, mediastinum and great vessels. The chest X-ray is used frequently to aid diagnosis of acute and chronic conditions.  

Patient position

• patient is erect facing the upright image receptor, the superior aspect of the receptor is 5 cm above the shoulder joints
• the chin is raised as to be out of the image field 
• shoulders are rotated anteriorly to allow the scapulae to move laterally off the lung fields, this can be achieved by either:
  • hands placed on the posterior aspect of the hips, elbows partially flexed rolling anterior or
  • hands are placed around the image receptor in a hugging motion with focus on lateral movement of the scapulae 
• shoulders are depressed to move the clavicles below the lung apices 

Technical factors

• posterioranterior projection
• ​suspended inspiration  
• centring point
  • the level of the 7^th thoracic vertebra, approximately the inferior angle of the scapulae  
• collimation
  • superiorly 5 cm above the shoulder joint to allow proper visualisation of the upper airways 
  • inferior to the inferior border of the 12^th rib 
  • lateral to the level of the acromioclavicular joints
• orientation
  • portrait or landscape 
• detector size
  • 35 cm x 43 cm or 43 cm x 35 cm
• exposure
  • 100-110 kVp
  • 4-8 mAs
• SID
  • 180 cm
• grid
  • yes 

Image technical evaluation 

The entire lung fields should be visible from the apices down to the lateral costophrenic angles. 

The chin should not be superimposing any structures.

Minimal to no superimposition of the scapulae boards on the lung fields.

Sternoclavicular joints are equal distant apart. 

The clavicle are in the same horizontal plane.

A minimum of ten posterior ribs are visualised above the diaphragm.

The ribs and thoracic cage are seen only faintly over the heart. 

Clear vascular markings of the lungs should be visible. 

Practical points

Rotation of a PA chest X-ray can mimic common disease processes and make it hard to produce a pertinent diagnosis.

The PA view is used to investigate a plethora of conditions and it is the radiographer's responsibility to ensure high quality diagnostic images are achieved consistently.

The medial aspect of the clavicles are a good indicator of rotation, if the medial clavicle is projected over the trachea the opposing side must be turned anterior. For example, if the medial end of the left clavicle is veering to the right of the patient projecting over the trachea; rotating the patient anteriorly to the right will correct this. 

Patients with longstanding history of emphysema or COPD will have abnormally long lungs compared to the general population, remember this when collimating superior to inferior.

Side marker placement is imperative, patients can have congenital conditions that mimic a mirrored image. 

Remember to explain to your patient what you are about to do, that is ask them to take a breath in and hold it. Many times this gives the patient time to prepare and results in a better breath hold and therefore a higher quality radiograph.

Always remember to tell your patient to breathbreathe again!