Intro to the chest radiograph
Matthew Bentz, MD
OHSU Diagnostic Radiology
Assistant Professor
2015
Goals for today
• Start with normal vs abnormal
• Try to develop a mental picture of normal
• See some commonly encountered and
important chest radiograph findings
Teaching points
1) Name the 5 densities that are seen on standard
radiographs
2) Choose and utilize a standardized way to view
each radiograph
3) Locate the following anatomic structures:
– Trachea, carina, subclavian artery and vein, SVC,
cavoatrial junction
4) Name the 6 patterns seen on chest imaging
Blank x ray film
Under exposure & over exposure
Density – the key to x ray films
Tissue depth and density matter
Depth and density matter
Physics too – physical density and
density to x rays both matter
Density Concept
• Organ boundaries are
seen only when the
densities are different
between the tissues
Examples:
– Pulmonary vessels are
sharply seen in normal
lungs (Soft tissue – air
interface)
– Airways are not seen in
normal lung (Air – Air
interface)
Airways not visible in normal lung
Airways visible in abnormal lung
Density is key!
• Converse is true also - If objects have, or develop, the
same density, they will be inseparable on CXR
Density is key!
• Converse is true also - If objects have, or develop, the
same density, they will be inseparable on CXR
?
Tissue appearance on x-rays
Air
Fat
Densities Water/tissue
Bone
Metal
Teaching point #1
• Name the 5 densities that are seen on standard
radiographs
Air
Fat
Densities Water/tissue
Bone
Metal
Conceptualize
• If you know what a cow
looks like
• And you know the color
purple
• You can recognize a
purple cow, even if
you’ve never see one
Quiz
Quiz
Air
Fat
Densities
Water/tissue
Bone
Metal
Quiz
Quiz
• Cartilage is water/soft
tissue density
• Since it is the same
density as the adjacent
tissue, there is no
visible boundary
– i.e. cartilage is invisible
on radiographs
Quiz #2
Quiz picture #3
“1 views is no views”
“1 views is no views”
Titanic
Normal chest X ray
Why look at each study the
same way?
Pretty easy to spot
Really hard to spot
Really hard to spot
Are all the lines and tubes ok?
A brief digression into technique
related issues
PA versus AP Examination
Scapula Position Can Help
AP View: 10% magnification
Patient body habitus
Rotation
Rotation: Medial Clavicles With Reference
To The Spinous Process (Arrows)
Rotated to RPO/LAO
Rotated to LPO/RAO
Approaches to a CXR
• Alphabet method
• Between, inside, outside the lungs
• Top down
• Other
– My approach: Abnormalities, right lung, left lung,
compare the two lungs, trachea, mediastinum, heart,
outside the lungs (including abdomen) and bones
Alphabet
• Air
Alphabet
• Air
• Bone
Alphabet
• Air
• Bone
• Cardiac
Alphabet
•
•
•
•
Air
Bone
Cardiac
Diaphragm
Alphabet
•
•
•
•
•
Air
Bone
Cardiac
Diaphragm
Everything else
BIO
• Between
• Inside
• Outside
BIO
• Between
• Inside
• Outside
BIO
• Between
• Inside
• Outside
Top Down
My Method