Susan Emerson BSc DVM MS DACVR Shares her insights on how to take the most accurate Small Animal Thoracic Radiographs.

1. 1
Optimizing
Thoracic
Radiographs
Small Animal

2. 2
General Principles
CENTER - the thorax on the detector plate
When we are talking about radiographs we want to keep safety in mind for
both the patient, and the person doing the imaging. In this presentation we
will cover some great ways to take high quality images while keeping you
and the animal safe!
COLLIMATE – out other regions
LABELING – make sure markers are in every view
Views - 3 view orthogonal study is the standard
TIMING – Inspiratory timing is important!
TECHNIQUE – optimized settings improve detail
POSITION – make sure patient is straight

3. 3
Radiation Safety
Learn more on
LowerTheDose.org
Veterinary Practices are required by law to follow radiation
safety protocol termed ALARA (As Low As Reasonably
Achievable).
The three main components of this protocol are
Devious Semikoli, but the
Little Blind Text didn’t
Minimize the time
Devious Semikoli, but the
Little Blind Text didn’t
Use Shielding
Devious Semikoli, but the
Little Blind Text didn’t
Double the distance
x2

4. 4
Sedation Is Your
Friend
Never put your hands in
the primary beam.
Even with the use of
protective gloves.
Human hands should NEVER be in the primary beam and should
ALWAYS have protection! Gloves protect from scatter but not from
primary beam- Human fingers exposed
Never put your hands in the primary beam
Always wear protective gloves
Remember, SEDATION IS YOUR FRIEND!

5. 5
Sedation Is
Your Friend!
● It can be near impossible to obtain
diagnostic images in some cases without
sedation due to patient
compliance/stress in a strange
environment.
● Use of sedation decreases patient stress
and decreases the technician time spent
acquiring radiographs.
● The cost of sedation is low compared to
the cost of the image and the cost of
technical time lost with an uncooperative
patient in most cases, and is well worth
the cost for the additional information
obtained!
Many facilities include the sedation
cost in the price of the imaging
study.

6. 6
Getting Your Images
Centered
● The most detail available in the most accurate representative
radiographic image is in the center of the field during the acquisition
● Beam obliquity occurs at the margins of the image which can cause
false positive or false negative findings in these regions
● Include all of the thoracic inlet
● Include ALL of the caudal dorsal lungs
and diaphragm (minimal beyond
those regions)
Relevant Anatomy to be included

7. 7
Why Not Just Do
Whole Body
Radiographs?
● The balance required between kVp and mAs is different
when imaging the thorax and abdomen due to the
different tissue types/components and thickness.
● In the CR (computed radiography) and DR (digital
radiography) systems which are now in nearly all
veterinary clinics, the computer also optimizes the image
after acquisition (post processing) based on the normal
tissue types in the region you have selected
Therefore choosing the correct study type
prior to acquisition is also important.This example
demonstrates the lack
of optimization

8. 8
● This is an extreme example but demonstrates the lack of
optimization for either body cavity.
● The thorax is overexposed with no detail in the lungs at
all. The abdomen also has incorrect technique balance
decreasing the contrast needed to distinguish the
abdominal organs.

9. 9
Here Are Some Reasons To Not Use
Whole Body Radiographs
Thoratic
Timing
Abdominal
Timing
The optimal timing for thoracic radiographs is at maximum
inspiration to allow the most air in the lungs. The air provides
contrast increasing the visibility of different tissues such as
vessels, bronchi and interstitial tissues
Thoratic Timing Is Important Because
The optimal timing for abdominal radiographs is at the pause
immediately following end of expiration when the diaphragm
relaxes, allowing the most room for the abdominal organs to
‘spread out’ improving the visualization of their margins.
Abdominal Timing Is Important Because

10. 10
Business
Perspective
It may seem like it saves time, but it decreases information
available which results in less information or less definitive
information in your radiology report. This is not helpful in
reaching a diagnosis or determining helpful therapy.
Business Perspective
Save Time
And Money
The cost in time and materials to perform separate properly
exposed 3 view studies for the thorax and for the abdomen in
digital radiography is very little compared with the increased
useful diagnostic information you receive from the
images/reports!
Save Time And Money

11. 11
Labeling The
Thorax And Why
It’s Important
Lateral views

12. 12
Minimum
Thorax Views
The aerated side of the lungs (‘upside’) during image
acquisition is the side that is primarily being assessed
while the unaerated (‘down side’) provides much less,
sometimes minimal information
Knowing laterality of acquisition is necessary to properly
localize structures/abnormalities in 3 dimensions
Minimum diagnostic study requires 2 views
● Right or Left lateral
IE: Knowing if nodules or masses are all
in one lung lobe may determine if
surgery is an option
Labeling is determined by which side of the patient is
‘down’ or closest to the plate (if patient is in right lateral
recumbency – that is a right lateral thoracic view).
● Ventrodorsal or Dorsoventral

13. 13
Why We Need
These Thorax Views
When in reality we could not see the pneumonia in the lung which was
positioned on the down side (due to lack of aeration in those lung lobes).
We would have missed
the pneumonia
Standard of Practice in North America is three
orthogonal views (both left and right laterals and
either a VD/DV).
● Aeration of the side closest to the plate is decreased
● Which in turn decreases the contrast needed to view components of
that lung
● This may prevent identification of abnormalities on the lateral view
which then may also be missed on the VD view where they could be
obscured by the heart or spine.

14. 14
Inspiratory
Timing
Air in the lungs provides contrast necessary to see
structure within the lung and improves
visualization of margins of other thoracic
structures
Expiratory timing may obscure
small areas of pathology/nodules
due to increased soft tissue
opacity in less aerated areas of
the lungs
Less aerated areas have a
general increased soft tissue
opacity which can be
misinterpreted as an interstitial
pattern
Expiratory Inspiratory

15. 15
Technique
Settings
● Use appropriate kVp and mAs determined using
patient measurement and technique chart
● These charts are created to maximize the
information available in the region you are imaging
and take into account what tissue types are present
in that region.
Correct
Exposure
Incorrect
Exposure
false positive change

16. 16
Lateral Thorax
Positioning
● Rib heads should be superimposed with the vertebral
bodies
● Left and right rib pairs are close to, or superimposed
with each other
● Deep narrow chested dogs may require a wedge
positioning device under the sternum/thoracic limbs
and/or abdomen/pelvic limbs to achieve this
Important to pull the forelimbs forward
avoiding superimposition with the
thorax

17. 17
Lateral
Poorly Positioned
Thorax
Lateral
Well Positioned
Thorax
Note rib heads, and rib pairs aligned Note rib heads, and rotation

18. 18
Right Lateral
Left Lateral
Use additional positioning devices as
needed to straighten achieving even
height from the table of the thoracic spine
and sternum.
Lateral Thorax
Positioning
Remember it's important to pull the
forelimbs forward avoiding
superimposition with the thorax.

19. 19
VD/DV Positioning
Sternum is superimposed with vertebral
bodies
Left and right hemi-thorax equal in width
VD - Use of a positioning trough is strongly
recommended as it decreases the number of
personnel required to stay in the room during
exposure and stabilizes patient positioning
Be careful to place edge of positioning trough
OUT of collimated area

20. 20
VD/DV Thorax
Positioning
Ensure to pull forelimbs well forward
equally on either side of the head

21. 21
If you don’t
have a
trough…

22. 22
Well
Positioned
VD Thorax
Note spinous processes form a
straight line of ‘dashes’ running
cranial to caudal in the middle of
the vertebral bodies
Well Positioned Note the line

23. 23
Poorly Positioned VD Thorax
Devious Semikoli, but the Little Blind Text didn’t but
the Little Blind packed her seven
State A
Devious Semikoli, but the Little Blind Text didn’t but
the Little Blind packed her seven
State B
Devious Semikoli, but the Little Blind Text didn’t but
the Little Blind packed her seven
State C
The Big Oxmox advised her not to do so, because there
were thousands of bad Commas, wild Question Marks
and devious Semikoli, but the
40%
20%
70%

24. 24
Poorly Positioned VD Thorax
Heart is artificially tipped and shifted left Most of lungs are obscured, heart is shifted and rotated
Rotated
Straight
Limb Not
Extended
Sternum
displaced
left
Rotated
Spine
Sternum

25. 25
CENTER and COLLIMATE
LABELING
THREE VIEWS
INSPIRATORY TIMING
OPTIMIZED TECHNIQUE
SETTINGS
STRAIGHT POSITIONING
Following These Principles Will
● increase the diagnostic information available
in your images used to determine most
appropriate next diagnostic steps and/or
therapy
● decrease/prevent false or misleading
information

26. 26
Connect With Us To
Learn More
(972) 869-2180
Phone
info@animalimaging.net
Emails
AnimalImaging.co