This document provides an overview of how to read a chest X-ray. It discusses the different types of chest X-ray views including posteroanterior (PA), anteroposterior (AP), lateral, and lordotic views. It describes how to assess exposure, inspiration level, rotation, and angulation. Key anatomical structures that should be evaluated are identified as the trachea, hilum, mediastinum, diaphragm, lungs, heart, bones, and soft tissues. Common abnormalities that may be seen involving these structures are also summarized such as tracheal deviation, hilar enlargement, and mediastinal masses.

1. Approach to a chest
X -ray
Presented by :Dr.K.S.Rithwik
Moderated by :Dr.Sathiq Ali

2. A chest X-ray is a
2Dimensional projection
of a 3 Dimensional
thoracic viscera.
It is a summated and
compressed image .

3. Reading into the Chest Radiograph
With below headings
1) Type of view
2) Exposure /Penetration
3) Inspiratory versus Expiratory film
4) Rotation
5) Angulation
6) Soft tissues and Bony structures
7) Trachea
8) Hilum / Mediastinum
9) Diaphragm
10) Lung fields
11) Cardia

4. Type of view
Chest x ray is having
1)Standard projections-based on direction of X-ray beam projection
Includes
a)PA view (posteroanterior view )
b)AP view (anteroposterior view )
c)Lateral view
2)Additional projection
• Lateral decubitus view
• Lordotic view

5. Standard projections of Chest Radiograph
1)PA View
• Posteroanterior view
• It is the preferred view
• This is obtained from fixed distance between X-ray tube and
cassette of 180 cms (6 feet )
• The ray of beam enters from posteroanteriorly with the film in
front of the patient

6. • Patient will be standing and in
full inspiration.
• Technique of x-ray beam
projection
X-ray beam passes through
the
chest from the back to the
front

8. Chest X ray PA view

10. • AP - Anteroposterior view
• Xray beam passes through the chest from the front to the back
• Beam is from anteroposteriorly with the film behind the patient
• Performed in patients who are not able to stand ,for supine ,ill
patients .

11. Technique of AP view

12. • Distance between the cassette and X-ray machine in AP view is
less than 180 cm approximately 100 cms-around 4 feet, because
of shorter distance structures appears to be magnified.

13. AP View of
CXR

14. Differences between PA and AP view

15. PA view and AP view comparison
Parameter PA view (Posteroanterior
view )
AP view (Anteroposterior
view )
1)Patient posture Erect (standing) Supine (lying on back )
2)Scapulae Away from the lung fields Overlie the lung fields
3)Clavicle Project over lung zones Project above lung apices
4)Distinct ribs end Posterior end Anterior end
5)Patients hands Placed on hips On the sides of thorax
6)Heart magnification minimal Moderate ,significant
7)Cardiothoracic ratio Normal 1:2 Spuriously increased

16. Differences between PA and AP view of
CXR
Parameter Posteroanterior view (PA
view )
Anterioposterior view (AP
view )
8)Diaphragm Lowest level Highest Level
9)Gastric air bubble Seen Not seen
10)Respiratory phase Deep inspiration Mid inspiration or
expiration
11)Lung Expansion Maximal Restricted
12)Lung Markings Normal , only lower zone
vessels prominent due to
gravity
Crowded upper zone
vessels unduly prominent
13)Lung Volume Normal Apparently reduced

17. Lateral View
• The ray of beam is from one side with the film placed on the
opposite side of the patient
• Technique : In a fit individual the arms are held high and away
from the thorax
• In a frail elderly patient the arms may have to be positioned in
front of the chest

19. Left Lateral
Chest X-ray

20. • Lateral CXR is useful to position an abnormality shown in frontal
CXR
• Is it anterior or posterior
• Which lobe is it in?
• Is it actually in a lobe?
• To check the tricky areas to look for
• Behind the heart
• Behind and infront of the hila
• Behind the domes of diaphragm

23. • Lateral Chest X-ray is useful for retrosternal, mediastinal masses,
pneumoniae, pleural effusion in the fissures

24. Lordotic view
• The AP lordotic chest radiograph (or AP axial chest radiograph)
demonstrates areas of the lung apices that appear obscured on
the PA/AP chest radiographic views.

25. Patient positioning:
• The patient is standing with feet approximately 30 cm away from
the image receptor, with back arched until upper back, shoulders
and head are against the image receptor.
• The shoulders and elbows are rolled anteriorly

26. Normal lordotic chest X-ray

27. Lateral decubitus view
• Patient position :
• the patient is lying either left lateral or right lateral on a trolley
on top of a radiolucent sponge
• It is useful to demonstrate small pleural effusions, or for the
investigation of pneumothorax and air trapping due to inhaled
foreign bodies

29. 2)Penetration /Exposure:
X-rays must adequately penetrate body parts to visualize the
structures, ideally one should be able to faintly see
a)The thoracic spine ,beyond the fourth thoracic level, through heart
shadow, if proper penetration is employed .

30. Under penetration
• If we cannot visualise the structures in the chest x-ray then the
radiograph is underpenetrated or too light
• It is diffusely bright and soft tissues are readily obscured,
especially those behind the heart

31. Over penetrated X-ray
• In this radiograph, all thoracic vertebrae visible through the heart
shadow
• Lung field darker than normal, have inadequate lung detail.

33. 1)Inspiratory film –should be able to count 9 to 10 posterior ribs
• Heart shadow should not be hidden by the diaphragm
2)Expiratory film –Poor inspiration can crowd lung markings
producing pseudo airspace
• Expiration reduces lung volume ,making a small pneumothorax
easier to see

34. Anatomical changes in chest in various
respiratory phases seen normally
Anatomical part Inspiration Expiration
1)Superior mediastinum normal Magnified
2)Trachea straight Buckled
3)Heart Normal size Magnified
4)CTR Normal Increased
5)Lungs Fully expanded Partially expanded
6)Bronchovascular markings Well spread out Crowded
7)Diaphragm Lowest Highest
8)Rib cage Anterior ends lower Anterior and posterior ends almost
at same level
9)Lung volume Normal Reduced

36. Rotation
• Normal Rotation
• Medial ends of bilateral clavicles are equidistant from
the midline or vertebral bodies

37. • Left rotated film
• If spinous process appears closer to the right clavicle, the patient
is rotated to left side
• Right rotated film
• If spinous process appears closer to the left clavicle ,the patient is
rotated towards the right side

38. Angulation
• Normal Angulation –clavicle
should lie over the 3 rd rib
(posterior end )with proper
angulation are clearly
visualised

39. Soft tissues
• Check neck and axillae for surgical emphysema, hematomas, and
tumours.
• Look for supraclavicular areas, tissues along the side of the
breasts.
• Look for breast shadows, pectoral muscle shadows.

40. Subcutaneous
Emphysema

41. Bony structures
1)Ribs
2)sternum
3)Spine
4)Shoulder girdle
5)Clavicles

42. • We have to look for shape of the thorax
• Is entire thorax visible ? 9 to 10 posterior ribs should visible in
deep inspiration.
• Look for rib fractures /notching /altered density
• Midline sternotomy sutures
• Intercostal spaces :width and angle ,wide or narrow

44. Trachea
• Look for trachea position ,whether it is midline or deviated ?
• Carina should be visible with slightly blacker outline over the lung
fields themselves, look for carinal angle (normal angle was acute)

45. Normal
position of
trachea

46. Tracheal
deviation

47. Causes of tracheal shift
Towards the side of the lung
lesion
Opposite to the side of the
lung lesion
1)Lung collapse 1)Tension pneumothorax
2)Lung fibrosis 2)Massive pleural effusion
3)pneumonectomy 3)Lung cancer
4)Diaphragmatic paralysis

48. Hilum
• Hilum is the wedge shaped area on the central portion of the
each lung where Bronchi, Pulmonary artery, vein leave the lung
99% of each hilar shadows is due to
1) Vessels – Pulmonary arteries and to a lesser extent veins
2) Fat, lymph nodes and bronchial walls are contents of hilum.
• Normal shape is concave

49. • Left hilum should never be lower than the right
• If left hilum appears to be lower than right hilum, then look for:
1)Collapse of either left lower lobe /or Right upper lobe.
2)enlargement of the right hilum (tumor /nodes)

50. Normal
hila in CXR

51. Causes of
Hilar
Enlargement
Unilateral Bilateral
Infection –tuberculosis
Viral infection in children
1)Sarcoidosis
2)Tumor :
Metastases
Lymphoma
Vascular-
a)pulmonary artery
stenosis b)pulmonary
artery aneurysm
3)Vascular
Pulmonary artery
hypertension
Tumor –Lymph node
metastases ,Lymphoma ,
bronchial carcinoma
4)Infection :
tuberculosis

52. CXR showing pulmonary artery hypertension

53. Chest X-ray findings in PAH
• Elevated cardiac apex due to right ventricular Hypertrophy
• Enlarged right atrium
• Prominent pulmonary outflow tract
• Enlarged pulmonary arteries
• Pruning of peripheral pulmonary vessels

54. Mediastinum
• Mediastinum is situated between the the pleural covering the
medial aspects of the right and left lungs
• Borders of the mediastinum in lateral CXR:
• Superiorly - the thoracic inlet
• Inferiorly - the diaphragm
• Laterally - Parietal pleura
• Anteriorly - the sternum
• Posteriorly - the vertebral column

55. Felson description of mediastinum

56. • Felson divided Mediastinum into
a) anterior mediastinum-boundaries
b) anteriorly - sternum, posteriorly anterior aspect of trachea, and
posterior margin of heart
c) Middle mediastinum: anteriorly
d) Posterior mediastinum

57. Mediastinal boundaries
compartment Anteriorly Posteriorly
Anterior Sternum Anterior aspect of trachea
posterior margin of the
heart
Middle Anterior aspect of trachea
and posterior margin of
trachea
A vertical line drawn along
the thoracic vertebrae 1 cm
behind their anterior
margins
Posterior Vertical line drawn along
the thoracic vertebrae 1 cm
behind their anterior
margins
Costovertebral junctions

58. Mediastinal contents
Compartment Main structures /tissues
Anterior Fat, lymphnodes, thymus /thymic
remnant, heart, ascending aorta
Middle Trachea, bronchi, lymph nodes,
oesophagus, descending aorta
posterior Paravertebral soft tissues

59. Mediastinal masses
Compartment Common causes
Anterior - 4 Ts
1)Thyroid mass
2)Thymoma,thymic carcinoma ,thymic cyst
3)Teratoma,seminoma
4)Lymphoma-hodgkins ,mediastinal diffuse large B cell
Lymphoma (DLBCL)
5)Parathyroid adenoma,hemagioma , lipoma ,liposarcoma
2)Middle Lymphadenopathy
Centrally situated lung tumors
Esophageal lesions –duplication cysts
3)Posterior Spinal /paraspinal abscess
Neurogenic tumors
Potts disease

60. C-xray
showing
Thymoma

61. Diaphragm
• Dome shaped
• Position : Right hemi diaphragm is located at 9 th -10th rib
posteriorly or 6 th rib anteriorly.
• Right hemidiaphragm is higher than the left by 2 cms because the
cardia keeps the left diaphragm down.
• Costophrenic and cardiophrenic angles
• Normal Height of diaphragm -2.5 cms

62. • Normally cardiophrenic and costophrenic angles should be clear,
sharp .
• They are obliterated due to fluid, fat or fibrosis.
• If there is opaque meniscus at a cardiophrenic angle, it requires
approximately 200 to 300 ml pleural fluid to efface the normal
sharp recess between the diaphragm and the ribs

63. CXR with
Normal
diaphragm

64. Blunting of left costophrenic angles in
pleural effusion

65. Flattening of
diaphragm
in COPD

66. Lung fields
• Lungs – Linear and fine nodular shadows of pulmonary vessels
• Blood vessels
• 40 % obscured by other tissues

67. Zones of lungs
• Two lines are drawn
1 ) One connecting the
anteroinferior end of the
second rib on both sides and
2) The second line connecting the
anteroinferior ends of the 4th
rib on both sides

68. • Two lines divides lungs into
• 3 zones :
1)Upper zone
2)Middle zone
3)Lower zone

70. Segments of lung

71. Silhoutee sign
• It actually denotes the loss of a silhoutee
• It is also known as loss of silhoutee sign/loss of contour sign.
• Loss of the anatomic border is described as positive silhoutee
sign.

72. • It is an An intrathoracic lesion touching a border of the heart
,aorta ,or diaphragm will obliterate that border on the
roentgenogram.
• An intrathoracic lesion not anatomically contiguous with a border
of one of these structures will not obliterate that border .

73. Silhoutee and its relationship with lobes of
lungs

74. Cardia

75. • Cardiomegaly-calculated by
CTR (cardiothoracic ratio )
CTR more than 0.50 in PA
view CXR was suggestive of
Cardiomegaly

76. If CTR is less than 25 %,It is small sized heart.
• Causes :
1)Bilateral emphysema
2)Anorexia nervosa
3)Addison’s disease

77. Differential diagnosis for gross
cardiomegaly
1. Pericardial effusion
2. Multivalvular heart disease
3. Sever Aortic regurgitation
4. Ebstein’s anomaly
5. Dilated Cardiomyopathy

78. Chamber enlargement Condition seen
Left atrial enlargement Enlarged left atrial appendage
Double atrial shadow
Straightening of left heart border
Left shift of aorta (bedford sign )
Pulmonary venous hypertension Grade 1 –cephalisation (prominence of veins of upper lobe
of lung )of pulmonary vasculature (PVP <_20 mm Hg )
Grade 2-Kerley lines -A,B,C(PVP 20 to 25 mm Hg)
Grade 3 :Batwing opacities (PVP >25mm Hg)
Pulmonary artery hypertension Enlarged pulmonary arteries >14mm in women and >16
mm in men with pruning of peripheral pulmonary vessels
Right atrial enlargement Right border more than 5.5cm from midline or 3.5 cm
from sternal border
Left ventricular enlargement Cardiomegaly with obtuse left cardiophrenic angle

79. Pleura
• Pleura is composed of dynamic membrane of mesothelial cells
and a deeper layer of connective tissue containing vessels ,nerves
and lymphatics
• Pleural membrane actively responds to adjacent inflammation
and to accumulates of the fluid .

80. Pleural effusion

81. Loculated Pleural Effusion and Encysted
Pleural Effusion

82. Pneumothorax
• Three cardinal features :
• A clearly defined line (the visceral pleura is visible )it will be
parallel to the chest wall.
• The upper part of the line curved at the lung apex
• The absence of lung markings .

83. Spontaneous and tension Pneumothorax

84. Hidden Areas of chest X-ray

85. ICU TUBES

86. LUNG CONSOLIDATION

87. Bronchopneumonia

88. Acute pulmonary edema vs ARDS

89. Lung Collapse

90. Interactive session

92. References
1)The chest X-ray –A
survival Guide (gerald de
Lacey ,simon morley )
2)Interpretation of chest
xray-by Dr.Balachandran
3)www.radiopedia.org 4)Davidsons principles of
internal medicine