This document provides an overview of how to interpret a normal chest x-ray. It describes the key anatomical structures visible in a chest x-ray like the lungs, heart, diaphragm and bones. It explains how to assess technical aspects such as inspiration level. Common views taken are described including PA, AP and lateral views. A systematic approach is outlined starting with the trachea and moving through each area of the chest. Key anatomical variations and measurements are also defined.

1. NORMAL CHEST X-RAY
Dr. Bijay Kumar Yadav
(1st Year Radiology Resident)
I.K KSMA, Bishkek
x-ray
Tube
Table
Film
cassette

2. Wilhelm Conrad Roentgen - Father of Radiology
 Nov 8, 1895 – Discovered
unknown radiations with
photographic effect which he
named ‘axa rays’
 He got the Nobel prize in 1901.

3. Common views of the chest X-Ray:
1. PA (Postero-anterior) view
2. AP (Antero-posterior) view
3. Lateral view
4. Lateral Decubitus
5. Oblique view
6. Apical / Lordotic view
7. Paired Inspiratory - Expiratory view

4. 1. PA VIEW:
 Most commonly ordered radiological investigation.
 Posterior-Anterior (PA) is the standard projection
 PA views are of higher quality and more accurately
assess heart size than AP images
 PA projection may not always be possible

5. PA Projection

7. 2. AP VIEW:
Lower quality
 Heart magnification (farther from film)
 Clavicles are projected more cranially above
lung apex
 Scapulae overlie lung fields
 Ribs appear horizontal
 Gastric bubble is absent

8. AP Projection

9. AP view CXR

10. PA view v/s AP View
IN PA VIEW:-
 Clavicles don’t project too high into the apices or
thrown above the apices (more horizontal)
 Heart wont be magnified over the mediastinum
therefore preventing the appearance of
cardiomegaly
 Scapula are away from the lung fields
 Ribs are obliquely oriented in PA view
 Spine and posterior ends of ribs are clearly seen

11. 3. LATERAL VIEW
 Routinely left lateral film
obtained
 In specific lesion, the
side of the interest is
positioned adjacent to
the film
 Should be viewed along
with the PA film

12. CHEST X-RAY: Systemic Approach
A. Technical Aspects
B. Trachea
C. Mediastinum & Heart
D. Hila
E. Diaphragm
F. CP Angles
G. Lungs:
i. Fields (Zones)
ii. Fissures
iii. Pulmonary Vessels
iv. Bronchial Vessels
H. Hidden Areas
I. Bony Framework
J. Soft Tissues

13. A. Technical Aspects:
 Patient Name, Date
 Adequate inspiration
 Centering & Rotation
 ExposureAdequate penetration
 Motion
 Side markers

14. a. Inspiration
 The diaphragm should be found at about the
level of 9 - 10th posterior rib or 5 - 6th anterior rib
on good inspiration
Inspiration Expiration
Note Changes In Heart Size And Vascularity Due
To Expiration.

15. Inspiration - Expiration
 Films taken after maximal inspiration &
expiration
 Advantage
• Helps in detection of focal or diffuse air
trapping – advantage in suspecting FB & small
pneumothorax
• Demonstration of diaphragmatic movement

16. b. Penetration
 On a good PA film, the
thoracic spine disc spaces
should be barely visible
through the heart but bony
details of the spine are not
usually seen.
 On the other hand
penetration is sufficient that
bronchovascular structures
can usually be seen through
the heart.

17. UNDERPENETRATION: Likelihood
of missing an abnormality
overlying by another structure
OVERPENETRATION: Results in loss
of visibility of low density lesion
e.g. Early Consolidation

18. c. Centering & Rotation
 Can be assessed by observing the clavicular
heads and determining whether they are equal
distance from the spinous process of the thoracic
vertebral bodies.
 Good centering: 1/3 of heart is to right & 2/3 to
left of midline.

20. c. Motion:
 Cardiac margin, diaphragm and pulmonary
vessels should be sharply marginated in a
completely still patient.

21. B. TRACHEA:
 Should be examined for:
• Narrowing
• Displacement
• Intraluminal lesions
 Position: Central, slightly deviated towards
Right around the aortic knuckle
 Calibre:
• Even
• Max. Coronal: 25mm (M), 21mm (F)

22.  Carina angle: 60 - 750 widening

23. C. MEDIASTINUM & HEART:
 Central dense shadow is formed by:
• Heart
• Mediastinum
• Sternum
• Spine

24. Cardiac Shadow
 Good centering:
– Heart:
• 2/3 left
• 1/3 right
 In chest x-ray heart examined for size, shape,
position, silhouette.

25.  Size measurement:
• CT ratio: < 50%
• Transverse cardiac
diameter:
< 15.5 cm (M)
< 14.5 cm (F)
 Heart size appears
enlarged on expiration,
supine film, AP film &
when diaphragms are
elevated

26. Borders

27. Silhouette sign:
 The silhouette sign is the absence of depiction
of an anatomic soft-tissue border resulting
from the juxtaposition of structures of similar
radiographic attenuation.
 Density difference  delineation of the outline.
 There are four basic densities in x-ray images:
a. Gas
b. Fat
c. Water / soft tissue
d. Bone / calcium
 Loss of density difference of the adjacent
structures  loss of silhouette.

28. D. HILA:
 Formed by superior
pulmonary vein & Basal
pulmonary artery
(Radiological Hilum)
 97% - left hilum is higher
(left pulmonary artery is
above bronchus)
 Hila should be of equal
density, similar size &
clearly defined concave
lateral borders

29. Structures in the Hilum
1. Pulmonary arteries & upper lobe veins-
significant contribution to hilar shadow
2. Normal LN- Not seen in plain radiography
3. Bronchi- walls seen end on

30. E. DIAPHRAGM:
 Right higher – Not more than 3 cm.
 May lie in same level & In small % left higher (~3%)

31.  On inspiration – Anterior 6th rib , Posterior 10th
rib (Erect film)
 Both domes – gentle curves- steepen towards
posterior angles
 Clearly defined upper borders except area where
heart rests & anterior cardio-phrenic angles (fat
pad)
 Loss of outline – adjacent tissue no air-
consolidation or pleural effusion
 Free intra peritoneal gas-under surface of
diaphragm: 2-3mm thick

32. Diaphragm (Normal Variants)
 Diaphragmatic Hump: Rt side anteriorly
 Eventration: Part of the muscle is absent- Left
side
 Scalopping: Rt side- short curves convex
upwards
 Muscle Slips: Rt side- short curves concave
upwards

33. Left v/s Right Dome Of Diaphragm:
 Anterior left hemidiaphragm is obliterated by the
cardiac contact; right is seen in entirity
 By identifying the fissures: left oblique fissure is contacts
diaphragm ~5 cm behind the anterior costophrenic angle
 On left lateral film, the right anterior and posterior
costophrenic sulci should project beyond the
corresponding left sided sulci as a result of x-ray beam
divergence
 By seeing air in stomach and splenic flexure below the
left hemidiaphragm

34. CP Angles
 Acute and well
defined
 Obliterated when
diaphragms are flat

35. E. LUNGS:
 Trachea
 Carina
 Right and Left
Pulmonary Bronchi
 Secondary Bronchi
 Tertiary Bronchi
 Bronchioles
 Alveolar Duct
 Alveoli

36. Zones Of Lungs
 Lower border of 2nd &
4th ribs separates the
zones zone 1
zone 2
zone 3

37. Lobes Of Lungs
 Right:- Upper, Middle & Lower
 Left:- Upper (Includes Lingular segment) & lower

38. RUL
 The Right upper lobe (RUL)
occupies the upper 1/3 of the
right lung.
 Posteriorly- The RUL is adjacent
to the first three to five ribs.
 Anteriorly- The RUL extends
inferiorly as far as the 4th right
anterior rib

39. RML
 The right middle lobe is
typically the smallest of the
three, and appears
triangular in shape, being
narrowest near the hilum

40. RLL
 The right lower lobe is the
largest of all three lobes,
separated from the others
by the major fissure.
 Posteriorly, the RLL extend
as far superiorly as the 6th
thoracic vertebral body, and
extends inferiorly to the
diaphragm.
 Review of the lateral plain
film surprisingly shows the
superior extent of the RLL.

41. Right Lobe Fissures
 These lobes can be separated
from one another by two
fissures.
 The minor fissure separates
the RUL from the RML, and
thus represents the visceral
pleural surfaces of both of
these lobes.
 The major fissure oriented
obliquely extends posteriorly
and superiorly
approximately to the level of
the 4th vertebral body.

42. LUL
 The lobar architecture of
the left lung is slightly
different than the right.
 Because there is no
defined left minor fissure,
there are only two lobes
on the left; the left upper

43. LLL
 Left lower lobes
 These two lobes are separated by
a major fissure, identical to that
seen on the right side, although
often slightly more inferior in
location.
 The portion of the left lung that
corresponds anatomically to the
right middle lobe is incorporated
into the left upper lobe.

44. Fissures Of Lungs
 Major: Right & Left oblique Fissure
 Minor: Right Horizontal Fissure

45. Pulmonary Vessels
1. Measure the right descending Pulmonary artery
Diameter- (16mm in Male & 15mm in Female)
2. Distribution of flow from apex to base
• At first intercostal space– normal vessels not more than 3
mm in diameter
• Erect- Lower lobe vessels prominent
• Supine- Equalize
3. Distribution of flow from central to peripheral -
tapering
• Vascular lung markings- Central 2/3rd

48. F. HIDDEN AREAS:
Apices: Partially obscured by ribs, costal cartilage,
clavicles & soft tissues
 Central lesions obscured by mediastinum and
hila
 Posterior & lateral basal segments of lower lobes
& posterior sulcus obscured by the downward
curve of the posterior diaphragm
 Hidden areas due to bones

49. G. BONY STRUCTURES:
• RIBS
• SCAPULA
• CLAVICLES
• SPINE
• STERNUM

52. H. SOFT TISSUE:
 General survey in chest wall, shoulders &
lower neck.
 Breast Shadows
 Supraclavicular areas
 Axillae
 Tissues along sides of Breasts

54. THANK YOU!!