Have a systematic approach Interpret the chest x ray in conjunction with the clinical findings Always compare with previous x ray if available to assess .

1. THE CHEST
X-RAY

2. Sources
• Felson’s Principles of Chest Roentgenology(6Th
Ed)
• Radiopedia
• Manual of chest X-ray- Dr Rajendra prasad
• Bedside respiratory medicine, Basanta Hazarika, V Dharma Rao

3. Basics
•German scientist Wilhelm Conrad
Röntgen, discovered x-ray radiation back
in 1895.
•kVp- kilo voltage peak
•mAs- milli ampere second
•mSv- milli sivert

4. •By convention, the routine frontal view is taken with
the patient upright and in full inspiration. The x-ray
beam is horizontal, and the x-ray tube is 6 feet from
the film or detector.
•To reduce the magnification and increase image
sharpness, the chest should be as close to the x-ray
cassette as possible, and the x-ray tube should be as
far from the cassette as practical.

5. General principal
•Have a systematic approach
•Interpret the chest x ray in conjunction
with the clinical findings
•Always compare with previous x ray if
available to assess the change

6. Basic Radiographic opacities
• Air
• Fat
• Water(soft tissue)
• calcium
• Bone
• X ray contrast
• metal

7. Technical aspects: before interpreting the
radiograph
•Identification
•Orientation
•Penetration/Exposure
•Rotation
•Inspiration/Expiration
•The side marker

8. Identification
•Correct patient
•Correct date & time

9. Orientation
• PA
• Lateral
• Oblique
• AP
• Lateral Decubitus
• Lordotic

10. PA VIEW
• Most frequently requested.
• Excellent visualization of lungs.
POSITIONING:
• The patient faces towards the
cassette and the tube is 6 feet(150-
180 cms) away from the patient.
• The chin is raised as to be out of the
image field.
• Shoulders are rotated anteriorly to
displace the scapulae from the
lungs.
• Usually taken with full inspiration

11. AP VIEW
• Usually taken when the patient is
too unwell to stand or leave the
bed.
• AP projection produces a
magnified mediastinal shadow due
to decreased distance of heart
from the light source and greater
distance from film

12. CXR PA v/s CXR AP
PA view-
1. Clavicle in lung field
2. Ribs slanted
3. Scapula outwards from lung field
4. Heart shadow normal
5. Usual view
AP view-
1. Clavicle remains at top of lung
field
2. Ribs lie more horizontal
3. Scapula comes in the lung field
4. Heart shadow looks larger
5. Usually bedridden and infants

13. LATERAL VIEW
• Patient stands upright
with 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
• Typically used in
conjunction with PA vies
to same side of chest to
determine 3 dimension
position of organs or
abnormal density

14. LATERAL DECUBITUS:
• Labeled according to the side
that is placed down
• It is helpful to assess the
volume of pleural effusion
and demonstrate whether a
pleural effusion is mobile or
loculated.
• Also helps detect
pneumothorax .

15. EXPOSURE/PENETRATION:
• In an ideal chest radiograph, the vertebral bodies
and disc spaces should be just visible through the
cardiac shadow, the left hemidiaphragm behind
the heart and vessels only up to 2/3 of lung area.
•The lack of appropriate penetration renders the
area “whiter” than with an adequate film and can
simulate pneumonia or effusion.

16. OVER-PENETRATION:
• Lung fields darker than normal—
may obscure subtle pathologies
• Spine is seen well beyond the
diaphragm.

17. UNDER-PENETRATION:
• Hemidiaphragms are obscured
• Pulmonary markings more
prominent than they actually
are.
• Inadequate lung details.

18. Rotation

19. INSPIRATION
On full inspiration
1. Anterior ends of the
sixth rib or posterior
ends of tenth rib are
above the Right hemi
diaphragm.
2. Heart shadow should
not be hidden by the
diaphragm.
Poor inspiratory film
1. 4 anterior ribs visible
2. False positive findings :
 Cardiomegaly (CTR 0.55)
 Opacity adjacent to
aortic knuckle.
 Inhomogeneous
opacification of bilateral
lower lung fields

21. EXPIRATORY STUDY
Helps visualize:
- Small Pneumothorax
- Air Trapping (Emphysema)
- Bronchial obstruction

22. THE SIDE MARKER
• The orientation of the aortic arch,
gastric bubble and heart should be
determined to confirm the normal
situs
• The side markers should be correct.

23. READING A CHEST X-RAY-A
SYSTEMATIC APPROACH
Are There Many Lung Lesions
Or
From outside to inside
Or
Inside to outside

25. Abdominal Structures
stomach bubble, splenic flexure of colon , liver, both diaphragm

26. Thoracic Cage
breast, ribs (anterior, posterior), scapula, clavicle,

27. Subcutaneous emphysema pneumomediastinum

28. Mediastinum
trachea and carina, aorta and heart, hilum

29. Lung Fields-Examined Twice

30. Lobar anatomy
• Right lung : upper lobe
middle lobe
lower lobe
Left lung: upper lobe
lower lobe

31. Lobar Anatomy
•Because the visceral pleura is less than 1 mm thick,
the x-ray beam must strike it parallel to its surface if
it is to be visible on the radiograph.
•The fissure normally appears as a thin white line.
•2 exceptions
•If a lobe is consolidated, fissure appear as edge
•If pleural fluid enters a fissure, fissure thickens

34. RML Consolidation

35. Azygous, Superior And Inferior Accessory

37. The Silhouette Sign
•Two substances of the same density, in direct
contact, cannot be differentiated from each
other on an x-ray. This phenomenon, the loss
of the normal radiographic silhouette
(contour), is called the silhouette sign.
•The silhouette sign may be misleading on and
underpenetrated radio graph.

39. RLL Silhouette
RML SILHOUTTE

40. MEDIASTINAL MASS OBSCURING TRACHEA
GUESS?

41. Air Bronchogram Sign
• Branching pulmonary vessels are visible in the lungs.
• The trachea and proximal main bronchi are surrounded by
mediastinal soft tissue and are visible. The peripheral bronchi are
not visible.
• When the lung is consolidated and the bronchi contain air, the dense
lung delineates the air-filled bronchi. Visualization of air in the
intrapulmonary bronchi on a chest radiography is called the air
bronchogram sign. The presence of air bronchogram suggest
alveolar consolidation

42. air
water

44. Patchy peripheral lung consolidation or interstitial disease usually does
not cause enough lung opacity to produce an air bronchogram.
Condition that hyperinflate the lungs do not cause air bronchogram.

45. •Air bronchogram may be seen in pneumonia,
pulmonary edema, pulmonary infarction and
certain chronic lung lesions .
•It is seen as long as the bronchi are filled with air
and there is surrounding water density.
•If the bronchus is obstructed by tumor or filled with
secretions, pulmonary consolidation would not
show an air bronchogram.
•An air bronchogram indicates open airways.
•Crowded air bronchogram suggest non obstructive
atelectasis.

46. Lobar Collapse
•Direct signs of collapse-
1. Displacement of interlobar
fissure (most reliable sign)
2. Loss of aeration
3. Vascular and bronchial
crowding/ crowded marking/
moving marker structure
• Indirect signs of collapse
1. Elevation of hemidiaphragm
2. Mediastinal displacement
3. Hilar displacement
4. Compensatory hyperinflation of
adjacent lung

47. LOBAR COLLAPSE

48. RUL collapse

49. RML collapse

50. GUESS?

51. LUL and lingula collapse

52. Five basic mechanism cause volume loss
• The natural tendency if the lung is to collapse
The five basic mechanism cause
1. Reabsorption of air distal to an obstruction of a bronchus
2. Relaxation of the lung as a result of air or fluid in the pleural space
3. Scarring causing lung contraction.
4. Decreased surfactant reducing lung distensibility (adhesive
atelectasis)
5. Hypoventilation as a result of central nervous system depression
of pain

53. mediastinum
•The trachea should be centrally located or slightly to
the right
•Aortic arch is the first convexity of the left side of
the mediastinum
•The pulmonary artery is the next convexity on the
left and branches should be traceable as it fans out
through the lungs
•Lateral margin of the superior vena cava lies above
the right heart border

54. compartment
Compartm
ent
Anteriorly posteriorly
Anterior Sternum Anterior aspect
of trachea and
posterior
margin of heart
Middle Anterior aspect of
trachea and
posterior margin of
heart
Vertical line
drown through
the thoracic
vertebrae 1 cm
behind their
anterior margin
posterior Vertical line drown
through the thoracic
vertebrae 1 cm
behind their
anterior margin
Costovertebral
junction

55. Mediastinal contents
compartment Main structures
anterior Fat, lymph nodes, thymus, heart,
ascending aorta
middle Trachea, bronchi, lymph nodes,
oesophagus, descending aorta
posterior Paravertebral soft tissue

56. Mediastinal lymph nodes cause ? tuberculosis

57. Morgagni hernia Bochdalek hernia

58. pneumomediastinum
• continuous diaphragm
sign: due to gas trapped
posterior to pericardium

59. THE PLEURAL AND EXTRAPLEURAL SPACE
•Periphery of the base of each pleural cavity
forms a deep gutter around the dome of the
corresponding hemidiaphragm
•Called as costophrenic sulcus or angle
•Most deepest is posterior angle

60. Pleural Diseases-Pleural effusion

61. Subpulmonic effusion
• The apparent elevation of
diaphragm in subpulmonic fluid
• Stomach bubble sign
• There is no stomach bubble in
right side, so rely on shape of
the right diaphragm. The apex
of each diaphragm is in
midclavicular. In subpulmonic
effusion the apex of the
diaphragm move to more lateral
position on either side.

62. Pleural Effusion(left lateral decubitus view)

63. Loculated

64. Encysted Effusion/ intrafissural
effusion/pseudotumor/ phantom tumor

65. Lung parenchyma

66. Patterns of Lung Diseases
• Linear(Reticular) Interstitial Thickening
• Nodular Interstitial thickening
• Alveolar Filling Disease

67. Reticular vs nodular

68. Alveolar filling defect cause
Acute –
• diffuse alveolar disease
• Bacterial pneumonia and severe
pulmonary oedema
• focal alveolar disease
• Infection
Subacute- granulomatous
infection : tuberculosis, fungal

69. Radiopaque shadow in one lung
• Agenesis of lung
• Massive pleural effusion
• Consolidation
• Collapse
• Fibrosis
• Mass
• pneumonectomy

70. consolidation
• Radiopaque shadow
• No mediastinal shift

71. Massive pleural effusion
• Homogenous
• Radiopaque
• Mediastinal shift to opposite
side

72. collapse
• Homogenous
• Radiopaque
• Mediastinal shift to same side

73. fibrosis
• Heterogenous
• Radiopaque
• Mediastinal shift to same side

74. Hyperslucent
• Technical – rotation, scoliosis
• Pneumothorax
• Soft tissue- subcutaneous emphysema
mastectomy/ atrophy of breast
atrophy/ removal of muscle overlying lung
Emphysema- obstructive/ bullous/ compensatory
Macleod/Swyer-James syndrome
Vascular- pulmonary artery absence/ obstrction

75. ANY ABNORMALITY ?

76. Tension pneumothorax
• Radiolucent
• Collapsed lung border
• Mediastinal shift to
opposite
• sudden dyspnea,
decreased unilateral
breath sounds and
jugular venous
distension

77. HYDROPNEUMOTHORAX

78. Infiltrative lesion
interstitial
• Infection: TB, mycoplasma,
pneumocystis, parasitic
• Neoplasm: lymphoma, leukemia
• Collagen disease: SLE,
polyarteritis nodosa,
scleroderma
• pneumoconiosis
Exudative/alveolar
• TB, pneumonia
• Pulmonary edema: cardiogenic,
non cardiogenic
• Alveolar haemorrhage
• Tumors
• Others: alveolar proteinosis,
Loffler’s syndrome
• Radiation pneumonitis

79. • Interstitial infiltrative right lung • Exudative bilateral lung

80. Cavitary lesion: When any alveolar lesion(mass, infiltrate,
nodule) become necrotic or caseous then liquefied ,material
is often expectorated and replaced with air called cavity.
How to define a cavity
• 2/3 of the wall should be visible
• bronchovascular marking are absent
• air fluid level may be present
How to describe a cavity
• site: upper/middle/lower zone
• Number: single/ multiple
• Size
• Wall- thin/thick
• Fluid level

81. Cavitary mass and
nodule

82. Air fluid level (necrotic
material only partially
expelled)
Calcification (in granulomatous
infections, if caseous material is not
expelled, it may healed and organize in
to a granuloma, that may frequently
calcify)

83. Intra pulmonary calcified shadow (healed
pulmonary TB)

84. Malignant cavity
• Thick walled
• Eccentric cavity
• Irregular inner wall of the cavity

85. aspergilloma
• An aspergilloma can be seen
as a mass within a cavity.
• The mass is typically
spherical or ovoid. The air
around the aspergilloma
takes a crescentic shape,
termed the Monod sign,
which is distinct from the air
crescent sign in
recovering invasive aspergill
osis.
• On different positioning of
the patient, the mass can be
shown to be mobile.

86. MILIARY PATTERN
• The term miliary
opacities refers to
innumerable, small 1-4
mm pulmonary
nodules
• Symmetrical
• Uniformly distributed

87. DIFFERNTIAL DIAGNOSIS OF MILIARY
PATTERN ON CHEST X-RAY
• Infection :-
• Bacterial: tubercular, bronchopneumonia, staphylococcal pneumonia
• Viral: CMV, mycoplasma, varicella
• Fungal: coccidiomycosis, histoplasmosis, blastomycosis
• Parasitic: Malaria, Kala-azar, tropical pulmonary eosinophilia
• Pneumoconiosis: anthracosis, silicosis
• Collagen disease: Scleroderma, SLE, RA
• Cardiac:- mitral stenosis, pulmonary embolism
• Neoplasm:
• primary: alveolar cell carcinoma, lymphoma, leukaemia
• Secondary: renal carcinoma, thyroid carcinoma
• Others: alveolar microlithiasis, idiopathic hemosiderosis, sarcoidosis

88. Nodular lesion
• Rounded or irregular
• Size < 3cm diameter
• Well of poorly defined
• Surrounded by aerated lung

89. Caused of nodular lesion
• Neoplasm:
• Benign: bronchial adenoma, fibroma, leiomyoma, lipoma
• Malignant: primary- bronchogenic carcinoma
secondary-lymphoma, sarcoma, mesothelioma
• Granuloma: tuberculosis, histoplasmosis,
coccidioidomycosis, brucella, echinococcus
• Hamartoma
• Simulated pulmonary nodule: skin tumour, nipple shadow,
rib lesion, foreign body, artifact
• Others: abscess, bulla, hematoma, infarct, loculated effusion

90. Mass lesion
• Pulmonary opacification
• Size more than 3 cm

91. Cause of mass lesion or rounded opacity
Solitary
• Infection:
• Bacterial: tuberculoma, lung abscess,
pneumonia
• Fungal: Aspergilloma, histoplasmosis,
coccidiomycosis,
• Parasitic :hydatid cyst
• Neoplasm:
• Benign: adenoma, fibroma
• Malignant: primary/ secondry
• Developmental: bronchogenic cyst,
sequestration of lung, aneurysm
• Others: foreign body, pulmonary
infarction, encysted effusion
Multiple
• Secondaries
• Multiple abscess
• Multiple encysted effusion
• Multiple hydatid cyst
• Multiple infarctions
• rheumatoid arthritis
• pneumoconiosis

92. carcinoma

93. Hydatid cyst
• Rounded
• Well defined margins

94. Cervical-thoracic sign

95. Cardiothoracic ratio
CTR is equal to the
transverse cardiac
diameter (TCD) divided by
the transthoracic diameter
(TTD) measured at the
inner border of the 9th rib
(CTR = TCD/TTD OR a+b/c)

96. Two methods
• Scale/ ruler method • Paper method

97. Left heart failure/ mitral stenosis
• normal
• Cephalisattion/vascular
redistribution- mild heart failure
• Interstial edema- moderate
heart failure
• Alveolar edema- severe failure
Note- determining cardiomegaly
and cephalisation is unreliable on
supine films

98. Take home message
•Look carefully for patient identification
details and technical issue
•Be systematic in approach
•It’s a chest x-ray, not a lung x ray
•Concentrate on hidden areas
•Compare with old films and lateral films