8. PA view AP view
• The posterior chest wall
is well shown
• The scapulae overlie the
upper lungs and the
clavicles are projected
more cranially over the
apices
• The neural arches are • The disc spaces of the
visualised lower cervical spine are
more clearly seen
12. Viewing the PA Film
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Name
Age
Date
Sex
Clinical information
13. Viewing the PA Film
Technical aspects
Centering
Penetration the vertebral body and spaces
should be just visible through the cardiac
shadow.
Degree of inspiration on full inspiration the
anterior ends of 6th ribs or the posterior ends of
10th are above the right hemidiaphragm.
14. Trachea it is in the midline then deviates
slightly to the right side at level of aortic
knuckle
Narrowing
Displacement
Intraluminal lesion
15. The mediastinum and heart
The central dense shadow seen on PA CXR
comprises the mediastinum, heart, spine and
sternum
The cardiac shadow lies to the left of the midline
and 1/3 to the right although it is quite variable
The transverse cardiac diameter normal for female
< 14.5 cm and for males < 15.5 cm.
The normal cardiothoracic ratio is < 50% on PA
film and < 60% in AP film.
An increase in excess of 1.5 cm in the transverse
diameter on comparable serial films is
significant.
16. All borders of the heart and mediastinum
should be clearly defined
In babies and young children the normal
thymus is a triangular sail shaped
structure with well defined borders which
may be wavy.
17.
18. Superior
Vessels
Vena
Cava Aortic Arch
Ascending
Aorta Pulmonary Artery
Right Left Atrium
Atrium
Inferior Left Ventricle
Vena
Cava
19. Aortic
Knob/Arch
Descending Ascending
Aorta Aorta
Left
Atrium
Right
Left Ventricle
Ventricle
Inferior Vena Cava
20. Diaphragm
In most patients the right hemidiaphragm is
higher than the left. May lie at the same
level, and in small percentage the left side
is higher.
A difference of > 3 cm in height is significant
Loss of outline indicates that the adjacent
tissue does not contain air.
21. The fissures
The main fissures
The horizontal fissure is seen often incompletely
on PA film
The oblique fissures are seen on lateral film
commence posteriorly at the level of T4 or T5
passing through the hilum. The left is steeper
and finishes 5cm behind the anterior
costophrenic angle, where as the right ends just
behind the angle.
Accessory fissures, the azygos fissure is
comma shaped and nearly always right sided.
29. The lungs
By comparing the lungs, areas of abnormal
translucency or uneven distribution of lung
markings are more easily detected.
30. The hila
In 97% of subjects the left hilum is higher
than the right. The hila should be of equal
density and similar size with clearly
defined concave lateral borders.
The lower lobe vessels are larger than those
of the upper lobes in erect position.
The right main bronchus is shorter, steeper
and wider than the left.
39. • Aortic arch
• Right pulmonary
artery
• Left pulmonary
artery
• Trachea & bronchi
Image credit: Curry International Tuberculosis Center, University of California, San Francisco 23
40.
41.
42.
43.
44.
45.
46. • The clear spaces
Retrosternal space normally this space is less than 3 cm
deep
Retrocardiac space
51. • The sternum should be studied carefully in cases of malignancy or
when there is a history of trauma.
52. Interpretation of abnormal film
• Radiological signs
The silhouette sign is the loss of an interface
by adjacent disease, when air in the
alveolar space is replaced by fluid or soft
tissue, there is no longer a difference in
radiodensity between that part of the lung
and the adjacent structures. Therfore the
silhouette is lost and the silhouette sign is
present.
54. • The air bronchogram is an important
sign showing that the lesion is
intrapulmonary. The bronchus , if air filled
but not fluid, become visible when air is
displaced from the surrounding
parenchyma. The air bronchogram is
seen as scattered linear translucencies.
