This document provides an introduction to chest radiography. It discusses the history of chest x-rays, the basic densities seen on x-rays, different views including PA, AP, lateral views, and how to evaluate technical adequacy. It also reviews normal pulmonary, pleural, and cardiac anatomy as seen on chest x-rays, and provides an overview of interpreting chest x-ray findings. The document is intended as an educational guide for radiology presenters and moderators.

1. INTRODUCTION TO
CHEST RADIOGRAPH
PRESENTER: DR ANUSHA
MODERATOR : DR SURESH

2. CONTENTS• History
• Introduction
• Basic densities
• Different views
• R-L side
• Evaluating the chest X-ray for technical adequacy
• Normal pulmonary anatomy
• Normal pleural anatomy
• Normal cardiac anatomy
• Hidden areas
• Mediastinum
• Hilum
• Interpreting the chest X-ray

3. HISTORY

4. Hand mit Ringen (Hand with
Rings)
Wilhelm Röntgen's first "medical"
X-ray, of his wife's hand, taken on
22 December 1895
One of the first chest radiographs taken by
Francis Henry Williams, the Father of Chest
Radiology in North America

5. INTRODUCTION➢CONVENTIONAL
RADIOGRAPHIC
IMAGES (x-rays) : are
produced by a
combination of ionizing
radiation and light
striking a
photosensitive surface,
which, in turn,
produces a latent
image that is
subsequently
processed.

6. INTRODUCTION
➢At first, the processing of film was carried out in a darkroom - the
films were then hung out to dry.
➢DIGITAL RADIOGRAPHY: the photographic film replaced by a
photosensitive cassette or plate that is processed by an electronic
reader and the image stored in a digital format.
➢PACS( Picture Archiving, Communications, and Storage): images
stored and archived for posterity and communicated to others on
computer servers

7. Air
Absorbs the least x-ray and appears “blackest” on
conventional radiographs
Fat Gray, somewhat darker (blacker) than soft tissue
Fluid or
soft tissue
Both fluid (e.g., blood) and soft tissue (e.g., muscle)
have the same densities on conventional radiographs
Calcium
The most dense, naturally occurring material (e.g.,
bones); absorbs most x-rays
Metal
Usually absorbs all x-rays and appears the “whitest”
(e.g., bullets, barium)
FIVE BASIC DENSITIES

8. FIVE BASIC DENSITIES

9. POSTERIOR- ANTERIOR
VIEW (PA VIEW)➢The X-ray beam is projected from
posterior to anterior
➢The patient is positioned facing the
receptor
➢The shoulders are rotated forward
and pressed downward in contact
with the receptor
➢The dorsal aspect of the hands are
placed behind and below the hips
with the elbows brought forward

10. POSTERIOR- ANTERIOR
VIEW (PA VIEW)➢The collimated horizontal beam is
directed at right-angles to the receptor
and centred at the level of the 8th
thoracic vertebrae (i.e. spinous
process of T7) which is coincident with
the lung midpoint
➢Exposure is made in full normal
arrested inspiration
➢CXR PA OBTAINED IN EXPIRATION-
Done to demonstrate small apical
pneumothorax and air trapping due to
inhaled foreign body

11. ANTERIOR- POSTERIOR
VIEW (AP VIEW)➢Used when the patient is
debilitated, immobilised, or
unable to cooperate with PA
procedure.
➢The collimated vertical beam is
angled caudally at right-angles
to the sternum .
➢Centred midway between the
sternal notch and the
xiphisternum.

12. PA VIEW AP VIEW
MEDIAL BORDER OF
SCAPULA
Outside the Lung fields Overlying the lung fields
CARDIA Normal Appearance Apparent Cardiomegaly
CLAVICLE
Lung field present above
the clavicles and are more
horizontal
Clavicle is above the apex
RIBS Posterior Ribs Distinct Anterior ribs distinct
GASTRIC BUBBLE Present Absent(Supine AP)

13. LATERAL VIEW
➢The arms are folded over the head
or raised above the head to rest on
a horizontal bar support
➢The collimated horizontal beam is
directed at right-angles to the
middle of the image receptor
coincident with the midaxillary line.
➢Centering point- mid coronal plane
at the level of T7 vertebra

14. LATERAL VIEW➢Used an adjunct to frontal
radiographs to determine
the three dimensional
position of organs or
abnormal densities.
➢Also used to assess
retrocardiac, retrosternal air
spaces.
➢Also used to assess the

15. OTHER VIEWS
1. Lateral Decubitus view-
i. Sub-pulmonic effusions that are not loculated
ii. Pneumothorax
2. Apical view- To visualise the apices
3. Lordotic views -Middle lobe atelectasis
4. Oblique View- To demonstrate rib fractures

16. R-L SIDE
➢By convention, while
interpreting the chest x ray, we
consider that the patient and
the interpreter are facing each
other.
➢The patient’s right side is on
your left side, and the patient’s
left side should be on your
right side
RIGHT LEFT

17. EVALUATING THE CHEST
RADIOGRAPH FOR TECHNICAL
ADEQUACY
1. Penetration
2. Inspiration
3. Rotation
4. Magnification
5. Angulation

18. EVALUATING THE CHEST RADIOGRAPH FOR TECHNICAL ADEQUACY
Penetration Should be able to see the spine through the heart
Inspiration Should see at least eight to nine posterior ribs
Rotation
Spinous process should fall equidistant between the
medial ends of the clavicles
Magnification
Anteroposterior films (mostly portable chest x-rays)
magnify the heart slightly
Angulation
Clavicle normally has an S shape, and medial end
superimposes onto the 3rd or 4th rib

19. PENETRATION/EXPOSURE
❑ The thoracic spine should be just visible through the cardiac
shadow
❑ Pulmonary vessels can be traced nearly to the edges of the lungs

20. PENETRATION
UNDER PENETRATED FILM
❖ Hemi diaphragms are
obscured- may mimic or hide
true disease
❖ Pulmonary markings more
prominent than they actually
are.- may be mistaken for CCF/
pulmonary fibrosis
❖ Soft tissue appears brighter.

21. PENETRATION
OVER PENETRATED FILM
❖ Lung fields darker than
normal - may obscure subtle
pathologies( pulmonary
nodules)
❖ Spine seen well beyond the
diaphragms
❖ Inadequate lung detail-
may be mistaken for
emphysema/
pneumothorax

22. INSPIRATION
➢Assessed by counting the
number of posterior ribs visible
above the diaphragm on the
frontal chest radiograph.
➢If 10 posterior ribs are visible,
it is an excellent inspiration.
➢In many hospitalized patients,
visualization of eight to nine
posterior ribs is a degree of
inspiration usually adequate for
accurate interpretation of the
image.

23. INSPIRATION
➢A poor inspiratory effort will
compress and crowd the lung
markings, especially at the
bases of the lungs near the
diaphragm which can be
mistaken for a lower lobe
pneumonia.

24. GOOD INSPIRATORY FILM

25. ANTERIOR RIBS POSTERIOR RIBS
Visible, but more difficult to see, on the
frontal chest radiograph.
Immediately more apparent to the eye on
frontal chest radiographs.
Oriented downward toward the feet. Oriented more or less horizontally
Attach to the sternum or to each other with
cartilage that usually is not visible until
later in life, when the cartilage may
calcify.
Attach to a thoracic vertebral body.

26. ROTATION
Based on the position of the
medial ends of each
clavicle(anterior structures)
relative to the spinous process
of the thoracic vertebral body
(posterior structure) between
the clavicles

27. ROTATION
•If the spinous process appears
to lie equidistant from the medial
end of each clavicle on the
frontal chest radiograph, there is
no rotation

28. If the spinous
process appears
closer to the medial
end of the left
clavicle, the patient
is rotated toward his
or her own right side
If the spinous
process appears
closer to the medial
end of the right
clavicle, the patient is
rotated toward her or
his own left side

29. PITFALLS OF EXCESSIVE
ROTATION
The hilum may appear larger on the
side rotated farther away from the
imaging cassette, because objects
farther from the imaging cassette tend
to be more magnified than objects
closer to the cassette.
Distorts the appearance of the normal
contours of the heart and hila.
The hemidiaphragm may appear
higher on the side rotated away from
the imaging cassette

30. MAGNIFICATION✓The closer any object is to the surface on which it is being imaged, the
more true to its actual size the resultant image will be.
✓In the standard PA chest radiograph, the heart, being an anterior
structure, is closer to the imaging surface and thus truer to its actual
size.
✓Also, the distance between the x-ray tube and the patient is shorter
when a portable AP image is obtained (about 40 inches) than when a
standard PA chest radiograph is exposed (taken by convention at 72
inches). The greater the distance the x-ray source is from the patient, the
less the degree of magnification.
✓Magnification usually is not an issue in assessing normal pulmonary

31. MAGNIFICATION
AP VIEW PA VIEW
Appearance of Heart on AP Study Probable Heart Size
Borderline enlarged Normal size
Significantly enlarged Enlarged
Touching, or almost touching, the left lateral
chest wall
Definitely enlarged

32. ANGULATION
✓Normally, the x-ray beam passes horizontally (parallel to the floor)
for an upright chest study, and in that position, the plane of the
thorax is perpendicular to the x-ray beam.
✓ Hospitalized patients in particular may not be able to sit
completely upright in bed in order that the x-ray beam may enter
the thorax with the patient’s head and thorax tilted backward.

33. ✓This has the same effect as angling the x-ray beam toward the
patient’s head, and the image obtained thus is called an apical
lordotic view of the chest.
✓On apical lordotic views, anterior structures in the chest (such as
the clavicles) are projected higher on the resultant radiographic
image than posterior structures in the chest, which are projected
lower.

34. Pitfall of excessive angulation:
In an apical lordotic chest study
the clavicles project at or above
the 1st ribs on the frontal image.
An apical lordotic view distorts the
appearance of the clavicles,
straightening their normal S-
shaped appearance.
Apical lordotic views may also
distort the appearance of other
structures in the thorax. The heart
may have an unusual shape,
which sometimes mimics
cardiomegaly and distorts the
normal appearance of the cardiac
borders.
The sharp border of the left
hemidiaphragm may be lost, which
could be mistaken as a sign of a
left pleural effusion or left lower
lobe pneumonia.
The clavicles are projected above the
1st ribs and that their usual S shape
is now straight (white arrows). The
lordotic view also distorts the shape
of the heart and produces spurious
obscuration of the left
hemidiaphragm (black arrow)

35. RECOGNISING THE
NORMAL PULMONARY
ANATOMY

36. ✓Dividing the chest radiograph into zones allows more careful
attention to be paid to each smaller area
✓The lower zones reach below the diaphragm as the normal lung
markings can be seen below the well defined edges of the
diaphragm

37. ✓Virtually all of the “white lines” we see in the lungs on a chest
radiograph are blood vessels.
✓Bronchi are mostly invisible on a normal chest radiograph
because they are normally very thin-walled, they contain air, and
they are surrounded by air.
✓Pulmonary arteries and pulmonary veins cannot be accurately
differentiated on a conventional radiograph.
VESSELS AND BRONCHI—
NORMAL LUNG MARKINGS

38. ✓ Blood vessels characteristically branch
and taper gradually from the hila
centrally to the peripheral margins of the
lungs.
✓In the upright position, the blood flow to
the bases is normally greater than the
flow to the apices because of the effect
of gravity. Therefore the size of the
vessels at the base is normally larger
than the size of the vessels at the apex
of the lung.
In the upright position, the lower-lobe
vessels (black circle) are larger in size
than the upper-lobe vessels (white
circle), and all vessels taper gradually
from central to peripheral (white
arrow). Alterations in pulmonary flow
or pressure may change these
relationships.

39. ✓The pleura is composed of 2 layers- parietal and visceral with
the pleural space in between
✓The visceral pleura is adherent to the lung and enfolds to form
the major and minor fissures.
✓Normally, there are several milliliters of fluid but no air in the
pleural space.
✓Neither the parietal pleura nor the visceral pleura is normally
visible on a conventional chest radiograph, except where the
two layers of visceral pleura enfold to form the fissures. Even
then, they are usually no thicker than a line drawn with the
point of a sharpened pencil.
NORMAL PLEURAL
ANATOMY

40. NORMAL CARDIAC
ANATOMY✓We can estimate the size of the cardiac silhouette on the
frontal chest radiograph using the cardiothoracic ratio, which is
a measurement of the widest transverse diam- eter of the
heart compared with the widest internal diameter of the rib
cage (from inside of rib to inside of rib at the level of the
diaphragm)
✓ In most normal adults at full inspiration, the cardiothoracic
ratio is <50%. That is, the size of the heart is usually less than
half of the internal diameter of the thoracic rib cage.

41. THE NORMAL CARDIAC
CONTOURS
The normal cardiac contours comprise a series bumps and indentations

42. • The ascending aorta should normally not project farther to the right than the right heart border (i.e.,
right atrium). The aortic knob is normally <35 mm (measured from the edge of the air-filled
trachea) and will normally push the trachea slightly to the right.
NORMAL AORTIC STENOSIS HYPERTENSION

43. ✓The main pulmonary artery segment is usually concave or flat.
In younger females, it may normally be convex outward.
✓The normal left atrium does not contribute to the border of the
heart on a nonrotated frontal chest radiograph.
✓An enlarged left atrium “fills-in” and straightens the normal
concavity just inferior to the main pulmonary artery segment and
may sometimes be visible on the right side of the heart.
✓Normally, the descending aorta parallels the spine and is barely
visible on the frontal radiograph of the chest. When it becomes
tortuous or uncoiled, it swings farther away from the thoracic
spine towards the patient’s left

44. ✓The lower portion of the left heart border is made up of the left
ventricle. The left ventricle is really a posterior ventricle and the
right ventricle is an anterior ventricle.
Heart size with stenotic versus regurgitant valve. A, There is poststenotic dilatation of the ascending aorta
(white arrow) from turbulent flow in this patient with aortic stenosis. The heart is not enlarged even
though this lesion produces left ventricular hypertrophy (dotted black double arrows). B, This patient has
aortic regurgitation. Note the extremely large left ventricle (solid black double arrows). Volume overload
will cause a greater increase in chamber size than will increased pressure.

45. HIDDEN AREAS

46. MEDIASTINUM
✓ The mediastinum is an area whose lateral margins are defined
by the medial borders of each lung, whose anterior margin is the
sternum and anterior chest wall, and whose posterior margin is
the spine, usually including the paravertebral gutters.
✓The mediastinum can be arbitrarily subdivided into three
compartments: the anterior, middle, and posterior
compartments, and each contains its favorite set of diseases.
✓The superior mediastinum, roughly the area above the plane of
the aortic arch, is a division which is now usually combined with
one of the other three compartments mentioned above.

47. Pitfall:
Since these compartments
have no true anatomic
boundaries, diseases from
one compartment may extend
into another compartment.
When a mediastinal
abnormality becomes
extensive or a mediastinal
mass becomes quite large, it
is often impossible to
determine which compartment
was its site of origin.

48. DIFFERENCES BETWEEN MEDIASTINAL AND PARENCHYMAL LUNG MASSES
MEDIASTINAL MASSES PARENCHYMAL MASSES
Smooth contour Surrounded by air
Will create obtuse angles with the lung
Abuts the mediastinal surface and creates
acute angles with the lung
Will not contain air bronchograms May contain air bronchograms
Mediastinal lines will be disrupted Will be on one side only

49. The anterior mediastinum is the compartment that extends
from the back of the sternum to the anterior border of the heart
and great vessels.
Mass What to Look for
Thyroid goiter
The only anterior mediastinal mass that routinely
deviates the trachea
Lymphoma
(lymphadenopathy)
Lobulated, polycyclic mass, frequently asymmetric, that
may occur in any compartment of the mediastinum
Thymoma
Look for a well-marginated mass that may be associated
with myasthenia gravis
Teratoma
Well-marginated mass that may contain fat and calcium,
especially seen on computed tomography scans
ANTERIOR MEDIASTINUM

50. MIDDLE MEDIASTINUM
✓The middle mediastinum is the compartment that extends from the
anterior border of the heart and aorta to the posterior border of the
heart and contains the heart, the origins of the great vessels,
trachea, and main bronchi, along with lymph nodes.
✓ Lymphadenopathy produces the most common mass in this
compartment.

51. POSTERIOR MEDIASTINUM
✓The posterior mediastinum is the compartment that extends from
the posterior border of the heart to the anterior border of the
vertebral column. For practical purposes, however, it is
considered to extend to either side of the spine into the
paravertebral gutters.
✓It contains the descending aorta, esophagus, and lymph nodes;
is the site of masses representing extramedullary hematopoiesis;
and most important, is the home of tumors of neural origin.

52. HILUM

53. INTERPRETING THE
CHEST XRAY
PREREQUISITES:
• Cross check patient details
• Look for the side markers
• Clinical history and findings
• Assess the quality of the radiograph
• Look for artifacts (if any)

54. R
I
P
A
B
C
D
E
F
G
H
I
Rotation
Inspiration
Penetration
Airway
Bones
Cardia
Diaphragm
Edges/ effusions
Fields
Gastric bubble
Hila
Insertions (tubes)

55. THANK YOU