10/20/2011
Introduction to
Radiographic Imaging
Image Interpretation
Objectives
» The student will be able to:
 Correctly
review a radiographic study
conventional anatomic terminology
 Correctly name a radiographic view
 Correctly “hang” a radiographic image
 List and explain the roentgen signs
 Know and identify the five radiographic
opacities
 Use
Review
» Radiograph is picture of x-rays able to
penetrate object – literal shadow of object
» Differential absorption of x-rays passing
through tissues is basis of radiography
» Radiograph is a two-dimensional depiction
of a three-dimensional object
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Principles of interpretation
» Review radiographs in appropriate environment
(low lighting, quiet)
» Be sure to have appropriate views and complete
study
» “Hang” or display radiographs in a standard
manner
» Make sure patient positioning and preparation
are adequate
» Make sure radiographic technique is appropriate
» Evaluate entire radiograph systematically
Principles of interpretation
» Radiographic interpretation
need not be mysterious
Knowledge of normal radiographic
anatomy and possible variants is
required!
 Be systematic
 Use basic radiographic signs
 Formulate a differential diagnosis
list

Conventional Terminology
» Use same terminology as in anatomy class
» Trunk: cranial, caudal, dorsal, ventral
» Head: rostral, caudal, dorsal ventral
» Extremity
 Above carpus and tarsus: cranial, caudal, proximal,
distal
 At and below carpus and tarsus:


Front limb: dorsal, palmar, proximal, distal
Rear limb: dorsal, plantar, proximal, distal
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Conventional Terminology
Application Question
» “Collimation” refers to restricting the x-ray
beam to the confines of the imaging plate.
What is one important reason to do this?
Radiographic Views
» Named according to the direction of the
x-ray beam as it penetrates the body part
from point-of-entrance to point-of-exit

For example, during a ventrodorsal
projection of the thorax, the beam enters the
ventral aspect of the thorax and leaves the
dorsal aspect of the thorax while the patient
is in dorsal recumbency
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Ventrodorsal (VD) view of thorax
X-ray beam
Ventrum
Dorsum
Radiographic Views
» Technically, lateral views of abdomen/thorax
should be described as “right to left lateral” or
“left to right lateral”

Convention shortens name:


Left lateral – patient in left lateral recumbency
Right lateral – patient in right lateral recumbency
» Technically, lateral views of extremities should
be described as “lateromedial” or “mediolateral”

Convention shortens name:

Lateral
Right lateral view of the abdomen
X-ray beam
Left lateral aspect
R
Right lateral aspect
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Dorsopalmar (DP) view of carpus
From Tech of Vet Rad, 5th
ed, Morgan JP, 1993
Radiographic Views
» Oblique views are views that are made off
angle from the standard lateral and
DP/CrCd views


Still named by the path of the x-ray beam
Technically should include angle of obliquity
(dorsal 60º lateral-palmaromedial oblique)
 Not

needed for standardized views
However, degree of obliquity does change
appearance
Dorsolateral-plantaromedial
(DLPM) oblique view of tarsus
From Tech of Vet Rad, 5th
ed, Morgan JP, 1993
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Why oblique views?
» Generally, abnormalities (fractures, bony
reactions, etc) are easier to see if the x-ray
beam strikes them tangentially
» Abnormalities are much more difficult to
see if the x-ray beam strikes them head-on
(en face)
» Nearly obligatory for complex structures
(equine carpus and tarsus, skull)
En face versus tangential
En face
Tangential
Application Question
» What is wrong with this radiograph?
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Radiographic Image
» Through and through concept
 For a given view (for example, craniocaudal
versus caudocranial) it generally does not
matter which way the beam enters and leaves
the object – image will appear the same
 Some
exception for organ sag and gas distribution
seen in thorax and abdomen
Radiographic image
Displaying or “hanging”
radiographs for interpretation
» By convention, images are always hung
on the view box or displayed on a monitor
in the same manner

Assists in developing picture of normal
anatomy
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Displaying or “hanging”
radiographs for interpretation
» Ventrodorsal (VD)/Dorsoventral (DV) view of
trunk


Cranial portion of image at top of viewing screen
Patient’s left positioned on viewer’s right
Ventrodorsal (VD)/
Dorsoventral (DV) View
Patient’s head (cranial)
Patient’s
left
Patient’s
right
Patient’s rear (caudal)
Displaying or “hanging”
radiographs for interpretation
» Lateral view of trunk
 Dorsal portion of image at top of viewing
screen
 Cranial portion of image positioned on
viewer’s left
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Lateral View
Patient’s dorsum
Patient’s
Head
(cranial)
Displaying or “hanging”
radiographs for interpretation
» Craniocaudal (CrCd)/Caudocranial (CdCr),
Dorsopalmar (DP)/Palmarodorsal (PD),
Dorsoplantar (DP)/Plantarodorsal (PD) of
extremities


Proximal portion of image at top of viewing screen
Viewer’s discretion how to place medial and lateral
aspects of image


Consider hanging as if looking at the patient
OR place lateral aspect of the limb on the viewer’s left
Dorsopalmar View
Proximal
L
A
T
E
R
A
L
L
A
T
E
R
A
L
Medial
Left
Right
Distal
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Dorsopalmar View
Proximal
L
A
T
E
R
A
L
L
A
T
E
R
A
L
Left
Right
Distal
Displaying or “hanging”
radiographs for interpretation
» Lateromedial (lateral)/mediolateral (lateral)
view of extremities
Proximal portion of image at top of viewing
screen
 Cranial (or dorsal) portion of image positioned
on viewer’s left

Lateromedial View
Proximal
Caudal
Cranial
Plantar
Dorsal
Distal
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Lateromedial View
Proximal
R
Cranial
Caudal
Distal
Application Question
» Why can’t we tell where the lumen of the
heart chambers are on a radiograph?
Displaying or “hanging”
radiographs for interpretation
» Important concept:
 You cannot determine right from left without
anatomic or artificial markers
 Must
incorporate positioning markers with images
convention, the positioning markers should be
placed at the lateral aspect or the cranial/dorsal
aspect of an extremity
 By
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Which Limb?
Radiographic Image
REMEMBER:
» Two-dimensional shadow of a threedimensional object

Need at least two orthogonal views to portray
object faithfully
Necessity of two views
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Necessity of two views
Roentgen Signs
» Identify radiographic abnormalities
(Roentgen signs)
Opacity
Size
 Shape
 Number
 Location/position/alignment
 Margination
 Function


Radiographic Opacities
» Five basic radiographic opacities
 Air (gas) opacity – black
 Fat opacity – dark gray
 Fluid/Soft tissue opacity – light gray
Bone
 Fluid:
water, blood, urine, etc
 Soft tissue: muscle, organ


Bone opacity – gray white
Metal opacity – white
Air
Fat
Fluid
Metal
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Radiographic Opacities
Bone
Air
Metal
Fat
Fluid/Soft tissue
Roentgen Signs
example
Roentgen Signs
example
» Opacity – soft tissue
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Roentgen Signs
example
» Size – 13 cm long x 8 cm high
Roentgen Signs
example
» Shape – ovoid
Roentgen Signs
example
» Number – one
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Roentgen Signs
example
» Location – cranioventral abdomen near tail of
spleen
Roentgen Signs
example
» Margination – irregular or lobulated
Roentgen Signs
example
» One ovoid, lobulated, 13 x 8 cm, soft
tissue mass in the cranioventral abdomen
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Goal of Imaging
» Create an image that will faithfully
represent what is going on in the area of
the patient being imaged while limiting
exposure to the patient and those handling
the patient
Application Question
» Which view of the tarsus is being made?
A. Craniocaudal
B. Caudocranial
C. Dorsoplantar
D. Plantarodorsal
Summary
» Radiographic views named by path of x-rays
using conventional terminology
» Always display or “hang” radiographs in a
standard manner
» Evaluate radiographs using Roentgen signs to
describe findings
» There are five basic radiographic opacities
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