This document provides guidance on interpreting a chest X-ray by reviewing the key anatomical structures and abnormalities to examine, including the cardiac shadow, mediastinum, hila, lungs, pleural spaces, bones, and soft tissues. The technical aspects of the image such as patient information, projection, inspiration, and penetration should first be checked. Common findings for each area are then described.

1. Chest X-Ray: Basics
Interpreting the CXR
General format:
Check the technical aspects
-Name, date, projection, rotation, penetration, inspiration
Cardiac shadow
-Size, shape, calcification
Mediastinum
-Position, width, outline, density, tracheobronchial tree
Hila
-Position, size, density, concave
Lungs
-Size, transradiancy, fissures, focal or generalised pulmonary
infiltration
Pleural spaces
-Effusions, soft tissue masses, calcification, pneumothorax
Bones
-Fractures, lytic or sclerotic lesions
Soft tissues
-Masses, calcification

2. Technical Aspects
Check the side
markers
Have you got L
and R the right
way around?

3. Assessment of rotation
Distance between medial
ends of the clavicles and
the spinous processes

4. Penetration
• Intervertebral disc
spaces just visible
through mid-cardiac
shadow
• Pulmonary structures
visible with clarity
• Few vessels in outer
third

5. Inspiration
Full inspiration:
• 6-7 anterior ribs
• 10-11 posterior ribs

6. Cardiac shadow
Heart Size
• Cardiac Transverse
Diameter (CTD) = a+b
< 15.5cm (males)
< 15.0cm (females)
• Cardio-Thoracic Ratio
(CTR) =a+b÷c+d
< 0.5

7. Cardiac configuration
• Dilated left ventricle:
-Ischaemic/dilated cardiomyopathy
-Aortic reflux
-Mitral reflux
-VSD, PDA
-Anaemia, hyperthyroid, Paget’s, AVF
• Failing left ventricle:
-AS, HTN, Coarctation
• Cardiomegaly (CTR > 0.5)
• Large third “mogul”
• Double density right heart border
• Displaced descending aorta
• Dilated left atrium:
-Mitral stenosis or myxoma
-Mitral reflux, VSD, PDA,
-ASD (late)

8. The mediastinum
• Mediastinal position
• Ratio:
- 1/3 to the Rt of
midline
- 2/3 to the Lt of
midline

9. Left heart border
• Aortic arch
•Main (left) PA
•Left atrial appendage
•Left ventricle
Right heart border
•Brachiocephalic vein
•SVC
•Right atrium
•IVC
- blurred or obscured and 'indistinct'
right heart border

10. Hila
•Position of hilar point:
-Right = 6th rib in mid-
axillary line
-Left = 0–2.5cm higher
•Outline:
- "V" shaped

11. Lungs
•Size
•Transradiancy
•Fissures
•Focal or generalised pulmonary
infiltration

12. Horizontal fissure
6th rib in mid-axillary line

13. Azygos fissure
4-layers of pleura, containing
azygos vein

14. Plural Spaces
•Effusions
•Soft tissue masses
•Calcification
•Pneumothorax

15. Bones
•Fractures
•Lytic or sclerotic lesions

16. Soft Tissues
•Masses
•Calcification