cxr basics

1. Dr Rikin Hasnani

2. • Introduction
• Procedure of taking an x ray
• Projections and views of chest X ray
• Reading a Chest X ray

3. • German physicist Wilhelm Röntgen was the first person
to discoverer X-rays in 1895, and he was the first to
systematically study them.
• He is the one who gave them the name "X-rays", though
many referred to these as "Röntgen rays"

4. • X-rays are a form of ionizing electromagnetic radiation.
• Most X-rays have a wavelength in the range of 0.01 to
10 nanometers
• The voltage used for diagnostic X rays is in range of 20 –
150kV

5. A radiograph is an X-ray image
obtained by placing a part of the patient
in front of an X-ray detector and then
illuminating it with a short X-ray pulse
X ray detectors used to collect images
are
• photographic film
• scintillator
• semiconductor diode
• photostimulable phosphor plates,
or PSP

6. Before the procedure
•The doctor/technician should explain the
procedure to pt and offer him/her opportunity to
ask any questions that pt might have about the
procedure.
•Generally, no prior preparation, such as fasting or
sedation, is required.
•Notify the radiologic technician if pt is pregnant or
suspect that pt may be pregnant.

7. •Pt is asked to remove any clothing, jewelry, or other
objects that may interfere with the particular view that
is ordered.
•Pt is positioned carefully so that the desired view of
the chest is obtained.
•For a standing or sitting film, pt stands or sits in front
of the X-ray plate. Pt is asked to roll his shoulders
forward, take in a deep breath, and hold it until the X-
ray exposure is made. For patients who are unable to
hold their breath, the radiologic technician takes the
picture at the appropriate time by watching the
breathing pattern.

8. • There are 5 basic radiographic densities
• Gas, fat, soft tissue (water), bone and metal
• Anatomic structures are recognized on x-ray by their
density differences
• Two substances of the same density in direct contact
can’t be differentiated
• Loss of the normal radiologic silhouette (contour) is
called the “silhouette sign”

13. On the left is a simulated patient in position for a
standard PA (posterior anterior) chest x-ray. On the
right is a normal PA film.

14. Supine AP (anteriorposterior) position, the x-ray tube is 40 inches
from the patient

16. 1) In AP view, the posterior chest is well
demonstrated.
2) The scapulae overlies the upper lung areas and
3) the clavicles are projected more cranially over the
apices.
4) The disc spaces of lower cervical spines are more
clearly seen.
5) The heart is magnified.
6) The ribs may appear more horizontal
7) Lung fields are shortened

20. • To localise a lesion seen on PA view
• To clarify lobar collapse or consolidation
• To explore a retrosternal or retrocardiac shadow
• To confirm the presence of encysted fluid in oblique
fissure (pseudotumor)

22. •This could be helpful to assess the volume of pleural
effusion and demonstrate whether a pleural effusion is
mobile or loculated.
•You could also look at the nondependent hemithorax
to confirm a pneumothorax in a patient who could not
be examined erect.
•Additionally, the dependent lung should increase in
density due to atelectasis from the weight of the
mediastinum putting pressure on it.
•Failure to do so indicates air trapping

23. It is used to visualize
the apex of the lung,
to pick-up
abnormalities such
as a Pancoast
tumour.

25. Reading a Chest
X ray

26. •Confirm Demographic data first

27. 1. Penetration
2. Inspiration
3. Angulation
4. Rotation

28. On a properly exposed chest radiograph:
• The lower thoracic vertebrae should be visible through
the heart
• The bronchovascular structures behind the heart
(trachea, aortic arch, pulmonary arteries, etc.) should be
seen

29. an example of a normal PA
film that is underpenetrated
In an underexposed chest
radiograph, the cardiac
shadow is opaque, with little
or no visibility of the thoracic
vertebrae.
The lungs may appear much
denser and whiter, much as
they might appear with
infiltrates present.

30. With greater exposure of the chest
radiograph, the heart becomes more
radiolucent and the lungs become
proportionately darker.
In an overexposed chest radiograph, the
air-filled lung periphery becomes extremely
radiolucent, and often gives the
appearance of lacking lung tissue, as
would be seen in a condition such as
emphysema

33. The chest radiograph should be obtained with the patient in
full inspiration to help assess intrapulmonary abnormalities.
At full inspiration, the diaphragm should be observed at
about the level of the 8th to 10th rib posteriorly, or the 5th
to 6th rib anteriorly.
Poor inspiration results in high diaphragms and crowding
of normal lung markings.

35. •A patient can appear to have a very abnormal chest if the film is taken
during expiration. - On the first film, the loss of the right heart border
silhouette would lead you to the diagnosis of a possible pneumonia.
However, the patient had taken a poor inspiration. - On repeat exam with
improved inspiration, the right heart border is normal.

39. • Airway
• Bones e.g. rib fractures and lytic bone lesions
• Cardiac silhoutte, (mediastenum)
• Cardiophrenic and Costophrenic angles
• Diaphragm,
• External lung fields
• Fields (lung parenchyma),
• Gas
• Hilum

40. • Start your assessment of every chest x-ray by looking at
the airways.
• The trachea should be central or slightly to the right.
• If the trachea is deviated, it is important to establish if this
is because the patient has been incorrectly positioned
(rotated), or if there is pathology.
• If the trachea is genuinely deviated you should then try
to decide if it has been pushed or pulled by a disease
process

41. •
You should be able to count and number the ribs, inspect
the scapulae, humerus and shoulders, clavicles, and see
the diaphragms overlying the posterior aspects of the
10th or 11th ribs .
• The spine and sternum are generally difficult to visualize
in detail on standard PA films due to overlying shadows.

43. • It is ovoid shadow with apex pointing towards left
occupying less than half of the transthorasic diameter.

46. On a frontal chest x-ray the
costophrenic angles should
form acute angles which are
sharp to a point.
--Often the term costophrenic
"blunting" is used to refer to the
presence of a pleural effusion.
This, however, is not always
correct and costophrenic angle
blunting can be related to
other pleural disease, or to
underlying lung disease.

49. Divide lung fields into zones: upper, middle, and
lower zones
-Upper: from the apex to 2nd costal cartilage
-Middle: between 2nd and 4th costal cartilage
-Lower: between 4th and 6th costal cartilage

51. Oblique fissure more clearly seen
on lateral view , extends from
T4-T5 vertebrae to reach the
diaphragm and 5cm behind the
costophrenic angle on left and just
behind the angle on right
Horizontal fissure more clearly
seen on PA view extending from
right hilum to 6th rib in the axillar
line.
Right oblique fissure
Left oblique fisure
Horizontal fissure

53. • Right upper lobe:

54. • Right middle lobe:

55. • Right lower lobe:

56. • Left lower lobe:

57. • Left upper lobe with Lingula:

58. • --Look at the hilum (which consists of main bronchus and
pulmonary arteries)
• --The left hilum should be higher than the right.
• --Compare shapes and densities on both sides.
• --The hila (lung roots) are mainly consisting of the major
bronchi and the pulmonary veins and arteries. These
structures pass through the narrow hila on each side and
then branch as they widen out into the lungs.
• --The hila are not symmetrical but contain the same basic
structures on each side.