A self explanatory presentation which gives you the basics of interpreting a normal chest X-ray

1. Normal X-ray
Dr. Kaustubh Mohite

2. Before starting reading an X-ray…..
• Patient identification details.
• Confirming the view (PA, AP, Lateral).
• Breath (Inspiration or Expiration).
• Penetration (Under or Over-exposed).
• Rotation.

3. Views
PA AP

4. Views
PA:
• Standard position.
• Patient stands upright with anterior wall of
chest placed against the front of the film.
• Shoulders are rotated forwards, ensuring that
the scapula does not obscure the lung fields.
• Taken on full inspiration.
• Clavicle projects over lung fields.
• Posterior ribs are more distinct.
AP:
• Used in debilitated, immobilized or non co-
operative patients.
• Film in behind the patient’s back in supine
position.
• Heart is at a greater distance from the film
and hence appears magnified.
• Scapula is seen over lung fields.
• Clavicle appears above the apex of lung
fields.
• Anterior ribs are more prominent.

5. Other positions:
Lateral:
• Patient stands with the left side of the
chest against the film and arms raised over
the head.
• Allows the viewer to see behind the heart
and diaphragmatic dome.
• Done in conjunction with PA view of the
same side of the chest to help determine
the 3D position of organs or abnormal
densities.

6. Lateral Decubitus:
• Patient lies on either the right or left side.
• Radiograph is labeled according to the side
that is placed down.
• Useful in revealing a pleural effusion that
cannot be easily observed in an upright
view.

7. Breath
Inspiration
6 anterior ribs visible
10 posterior ribs visible
Expiration

8. Penetration:
Underexposure:
• Cardiac shadow is
opaque, with little or no
visible thoracic vertebra.
• Lungs appear much
denser and whiter, giving
appearance of infiltrates.
Overexposure:
• Heart becomes more
radiolucent and lungs
become proportionately
darker.
• Appearance of lacking
lung tissue, as seen in
conditions like
emphysema

9. Things to be seen in a normal Chest X-ray….
• Trachea and major bronchi.
• Hilar structures.
• Lung Zones.
• Pleura and pleural spaces.
• Diaphragm.
• Costophrenic recesses and angles
• Heart size and contours.
• Mediastinal contours.
• Soft tissues.
• Bones.

10. To keep it simple……
A – Airway
B – Bones and Soft tissue
C – Cardia
D – Diaphragm
E – Effusions
F – Fields (Lung Fields)
G – Gastric Bubble
H – Hila and Mediastinum

11. Visible Structures:
1 – Trachea
2 – Hilum
3 – Lung
4 – Diaphragm
5 – Heart
6 – Aortic knuckle
7 – Ribs
8 – Scapulae
9 – Breast
10 – Bowel gas
Invisible Structures:
• Sternum
• Oesophagus
• Spine
• Pleura
• Fissures
• Aorta

12. Trachea and Major Bronchi:
• Start your assessment of every
chest X-ray by looking at the
airways. The trachea should be
central or slightly to the right
at the level of the aortic
knuckle.
• If the trachea is deviated, it is
important to establish if this is
because of patient rotation or
if it is due to pathology.
• If the trachea is genuinely
deviated you should then try to
decide if it has been pushed or
pulled by a disease process.

13. Hilar structures:
• Each hilar point is the
angle formed where the
upper and lower lobe
pulmonary vessels meet.
• They are useful points of
reference to determine the
position of the hila.
• Commonly the left hilum is
higher than the right

14. Pulmonary Arteries:
• Deoxygenated blood (blue arrows) is
pumped upwards out of the right
ventricle (RV) via the main
pulmonary artery (Main PA).
• The main PA divides into left
pulmonary artery (Left PA) and right
pulmonary artery (Right PA) which
pass into the lungs via the hila.
• The left PA hooks backwards over the
left main bronchus.
• The right PA passes anterior to the
right main bronchus.

15. Lung Zones:
Note that the lower zones reach below the diaphragm
(dotted white line) – the lungs pass behind the
dome of the diaphragm into the posterior sulcus of
each hemithorax (asterisks)

16. Pleura and pleural spaces:
• Trace round the entire edge of the lung
where pleural abnormalities are more readily
seen.
• Start and end at the hila.

17. Lung Lobes and fissures:

18. • Found normally in 1 – 2% individuals.
• Azygos vein passes horizontally along the
right side of the mediastinum.
• In those with an azygos fissure a small section
of the right upper lobe (an azygos lobe)
develops medial to the vein which is pushed
away from the mediastinum.
• It is surrounded by both parietal and visceral
pleura.
• Four layers of pleura, two parietal layers and
two visceral layers.
• The appearance resembles a tadpole - the
head is the azygos vein and the tail the azygos
fissure.

19. Diaphragm:
• The right hemidiaphragm is slightly higher than the left.
• The liver is located inferior to the right hemidiaphragm.
• The stomach and spleen are located inferior to the left
hemidiaphragm.
• Lung markings are visible below the diaphragm on both
sides – most clearly through the stomach bubble.
• The cardio-phrenic angles (asterisks) are the points at
which the hemidiaphragms meet the heart.
• On both sides, the contour of the hemidiaphragm
(dotted line) should be seen passing medially as far as
the spine.

20. Costophrenic recesses and angles:
• The costophrenic recesses are seen on each side as
the costophrenic angles.
• The costophrenic angles are formed by the lateral
chest wall and the dome of each hemidiaphragm.

21. Heart Size and Contours:
• The left heart contour (red line) consists of
the left lateral border of the Left Ventricle
(LV).
• The right heart contour is the right lateral
border of the Right Atrium (RA).

22. Cardio – Thoracic ratio:
• Cardiac size is measured by drawing vertical parallel lines
down the most lateral points of the heart and measuring
between them.
• Thoracic width is measured by drawing vertical parallel
lines down the inner aspect of the widest points of the
rib cage, and measuring between them.
• The cardio-thoracic ratio can then be calculated.
• Here the CTR is approximately 15 : 33 (cm) and is
therefore within the normal limit of 50%.

23. Mediastinal Contours:
• The aortic knuckle represents the left
lateral edge of the aorta as it arches
backwards over the left main
bronchus.
• The contour of the descending
thoracic aorta can be seen in
continuation from the aortic knuckle.
• Displacement or loss of definition of
these contours can indicate diseases
such as aortic aneurysm or adjacent
lung consolidation.

24. Normal Aorto-pulmonary window:
• The aortopulmonary window is located
between the Aortic Knuckle (AK) and the
Left Pulmonary Artery (LPA).
• It is a space where abnormal enlargement
of mediastinal lymph nodes can be seen on
a chest X-ray.

25. Bones:
Clavicle / Ribs:
• Act as landmarks
• Less than 5 ribs indicates incomplete inspiration.
• More than 7 ribs suggests lung hyper-expansion.
• Anterior end of the 7th rib (asterisk) intersects
the diaphragm at the mid-clavicular line.
• The subcostal grooves are visible on the underside
of the ribs (red highlights).
• The spine can be seen through the heart
indicating adequate X-ray penetration.

26. Take home points….
• Do not forget the pre-requisites before you start to read a chest X-ray.
• Always have a systematic approach while interpreting an X-ray making sure
that you have seen all the components as mentioned above.
• Always focus more on the prominent observations rather than commenting
over the rare abnormalities.
• The more the number of normal X-rays you see, the easier it is to find out
abnormal X-rays.

27. Thank you….