Citation, DOI & article data
Citation:
Murphy, A., Bickle, I. Chest (lateral view). Reference article, Radiopaedia.org. (accessed on 08 Nov 2022) //doi.org/10.53347/rID-44931
The lateral chest view examines the lungs, bony thoracic cavity, mediastinum, and great vessels.
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This orthogonal view to a frontal chest radiograph may be performed as an adjunct in cases where there is diagnostic uncertainty. The lateral chest view can be particularly useful in assessing the retrosternal and retrocardiac airspaces.
If locating a specific pulmonary opacity within the chest cavity, it would be useful for requesting doctors to ensure that the side of the opacity is mentioned in their clinical notes. This will allow radiographers/imaging technologists to image with the side of interest against the image receptor, hence reducing any magnification from an increased SID. Otherwise, a left lateral view is the default and preferred side as it demonstrates better anatomical detail of the heart.
- standing upright
- left side of the thorax adjacent to the
image receptor
- left shoulder placed firmly against the image receptor
- both arms raised above the head, preventing superimposition over the chest
- arms can be placed on the head or holding onto handles, if available
- chin raised out of the image field
- midsagittal plane must be perpendicular to the divergent beam, therefore:
- using the paravertebral gutter technique (see Figure 1) right side rotated 5-10° anterior
- lateral projection
- suspended inspiration
- centering point
- the midcoronal plane of the level of the 7th thoracic vertebra, approximately the inferior angle of the scapulae
- collimation
- superiorly 5 cm above the shoulder joint to allow proper visualization of the upper airways
- inferior to the inferior border of the 12th rib
- anteroposterior to the level of the acromioclavicular joints
-
orientation
- portrait
- detector size
- 35 cm x 43 cm
- exposure
- 100-110 kVp
- 8-12 mAs
- SID
- 180 cm
- grid
- yes
The entire lung fields should be visible superior from the apices inferior to the posterior costophrenic angle
- the chin should not be superimposing any structures
- there is superimposition of the anterior ribs
- the sternum is seen in profile
- superimposition of the posterior costophrenic recess
- a minimum of ten posterior ribs are visualized above the diaphragm
- the ribs and thoracic cage are seen only faintly over the heart
- clear vascular markings of the lungs should be visible
The same principle of positioning can be applied to patients in a chair.
Before exposing ensure your patient is not leaning forward or backwards too much, this will result in anatomy being cut off.
Patients with a 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 2.
Patients with scoliosis may not demonstrate the traditional indicators of a correctly positioned lateral radiograph; it is important to note that patients with this condition particularly in the thoracic region will appear rotated by conventional evaluation, yet this is not the case.
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 better breath-hold and therefore a higher quality radiograph.
Always remember to tell your patient to breathe again!
References
Related articles: Imaging in practice
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Chest X-ray Quality
Projection
Key points
- Posterior-Anterior (PA) is the standard projection
- PA projection is not always possible
- Both PA and AP views are viewed as if looking at the patient from the front
- PA views are of higher quality and more accurately assess heart size than AP images
- If an AP projection is performed, ask yourself if the clinical question can still be answered
Posterior-Anterior (PA) projection
The standard chest radiograph is acquired with the patient standing up, and with the X-ray beam passing through the patient from Posterior to Anterior (PA).
The chest X-ray image produced is viewed as if looking at the patient from the front, face-to-face. The heart is on the right side of the image as you look at it.
PA projection
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PA projection
- X-rays pass from the posterior to the anterior of the patient - hence Posterior-Anterior (PA) projection. The image is viewed as if looking at the patient face-to-face.
Sometimes it is not possible for radiographers to acquire a PA chest X-ray. This is usually because the patient is too unwell to stand. The chest X-ray image is still viewed as if looking at the patient face-to-face.Anterior-Posterior (AP)
projection
AP projection
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AP projection
- X-rays pass from the anterior to the posterior of the patient - hence Anterior-Posterior (AP) projection. The image is still viewed as if looking at the patient face-to-face.
The heart, being an anterior structure within the chest, is magnified by an AP view. Magnification is exaggerated further by the shorter distance between the X-ray
source and the patient, often required when acquiring an AP image. This leads to a more divergent beam to cover the same anatomical field. As a rule of thumb, you should never consider the heart size to be enlarged if the projection used is AP. If however the heart size is normal on an AP view, then you can say it is not enlarged.AP v PA - Heart size
AP v PA projection
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AP v PA projection
- The upper diagram shows an AP projection. Heart size is exaggerated because the heart is relatively farther from the detector, and also because the X-ray beam is more divergent as the source is nearer the patient.
- The lower diagram shows a conventional PA projection. The apparent heart size is nearer to the real size, as the heart is relatively nearer the detector. Magnification of the heart is also minimised by use of a narrower beam, produced by the increased distance between the source and the patient.
Radiographers will often label a chest X-ray as either PA or AP. If the image is not labelled, it is usually fair to assume it is a standard PA view.
If you are not sure then look at the medial edges of each scapula.AP v PA - Scapular edges
AP projection - example
Hover on/off image to show/hide findings
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AP projection - example
- AP projection images are of lower quality than PA images. Compare this image with the PA view below.
- The image has been acquired by a mobile X-ray unit in the resuscitation room. Note the AP SITTING label.
- The scapulae are not retracted laterally and they remain projected over each lung.
- Heart size is exaggerated (cardiothoracic ratio approximately 50%). If seen on a PA image this would be at the borderline for cardiac enlargement.
- The radiograph was repeated - see below.
In order to take a PA view the patient places his or her arms around the side of the detector plate, or stands with hands on hips. This ensures the scapulae are rotated laterally and no longer overlap the lungs.
PA projection - example
Hover on/off image to show/hide findings
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Click image to align with top of page
PA projection - example
- This PA X-ray is of the same patient as the image above.
- The edges of the scapulae are retracted laterally with only a small portion projected over each lung. The lungs are therefore more easily seen.
- The cardiothoracic ratio is clearly well within the normal limit of 50%.