RHPT – 485 LEVEL – 8
READING IN MEDICAL IMAGING
INTRODUCTION
OBJECTIVES OF THE TOPIC-1
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At the end of the lecture students must be able to recognize different types of
imaging modalities related to physical therapy.
Students must be able to outline/mention different names of typical body regions
that plain x-ray is used to evaluate.
Students must be able to describe the difference between types of imaging
modalities related to physical therapy based on their physical properties.
Students must be able to recognize different views of the imaging film.
Students must be able to outline/mention indications and contraindications of
different types of imaging modalities related to physical therapy.
X-RAY
INTRODUCTION

Discovered and named by
Dr. W. C. Röentgen at
University of Würzburg, 1895

Awarded first Nobel prize for
physics, 1901
• In 1895 Wilhelm Conrad Roentgen discovered X-rays, so
paving the way for the development of a new branch of
medicine called radiology.
• Initially, radiology was the science of 'X-rays', but today it
involves a variety of imaging techniques to study and
investigate patients so that a diagnosis can be achieved.
• In addition, therapeutic procedures are performed by
radiologists under image guidance, a branch also known as
interventional radiology.
FIRST X-RAY
Roentgen’s wife's hand
What are the Different Imaging Modalities

Radiography “plain films”
Computed axial tomography “CT”
(Positron Imaging Tomography “PET”, Single Photon
Emission CT “SPECT”, Combined PET-CT)
 Magnetic resonance imaging “MRI”
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Ultrasound “US”
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Interventional radiology “angio”
RADIOLOGY TOOLS
X- RAY
ULTRASOUND
NUCLEAR MEDICINE
MAGNETIC RESONANCE
COMPUTED TOMOGRAPHY
7
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IONIZING RADIATION
X-ray, CT, Nuclear Medicine
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SOUND WAVES
Ultrasound
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MAGNETIC FIELDS / RADIO WAVES
Magnetic Resonance

IONIZING RADIATION
X-ray, CT, Nuclear Medicine

SOUND WAVES
Ultrasound

MAGNETIC FIELDS / RADIO WAVES
Magnetic Resonance
To image the patient a energy source is directed into a
volume of tissue and an image is created of the tissue
interaction.
How to Approach Reading any Image
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Identify the patient
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When was the image taken
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Are these the proper images
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The five densities
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Are the images technically adequate
Radiography – X - Ray

Also called “plain films” or “standard films”
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Image formed using broad beam ionizing radiation
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The image formed is related to the subjects density

May involve the use of contrast agents
 Iodinated
 Barium
 Air
X-RAY 
High Energy Photon
--Kilo Electron Volts
 Ionizing Radiation
X-ray beam
 Exposes Film /
Detector
 Projection Data
detector
X-rays are short-wave electromagnetic radiation produced by
accelerating electrons across an evacuated tube onto a tungsten anode
using a high voltage.
X-RAYS PLAIN FILM
RADIOGRAPHY - Clinical uses
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Chest
Bones
Spine / Extremities / Skull
Soft tissue
Mammography / Abdomen
These are typical body regions that plain x-ray is used to
evaluate.
X - RAY --- FIVE BASIC DENSITIES
 Air / Gas
 Soft Tissue / Fluid
filled space
 Bone
 Fat
 Metal
• The x-rays can traverse tissue to create the image.
• We can only separate the 5 basic densities noted.
Air / Gas, Soft tissue / Fluid filled space, Bone, Fat
& Metal.
• Here we see the Air in the lungs, the soft tissue of
the heart and the bone density of the ribs.
• Water will appear of the same density as soft
tissue and cannot be separated. Fat is difficult to
see on the chest and better noted on abdominal xrays
CONTRAST RADIOGRAPHY

Injection, ingestion, or other placement of opaque material
within the body.
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Improves visualization and tissue separation.

Can demonstrate functional anatomy and pathology.
Computed Axial Tomography

Also called CAT scanning or “CT”

Image formed using a rotating thin beam(s) of ionizing
radiation
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Image “slices” reconstructed by computation

The image formed is related to the subjects density

Image display on computer or multiple films
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New technology is multislice helical scanner
Uses - CT
• Oncology staging
• Trauma assessment
• Guiding biopsies
• Radiotherapy planning
COMPUTED TOMOGRAPHY
CT
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HIGH ENERGY PHOTON

IONIZING RADIATION
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EXPOSES DETECTOR

TOMOGRAPHIC DATA
Here the yellow line is showing the level where the CT section is made through
the upper abdomen at the level of the liver.
LT
Interventional Radiology
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Also called angiography or “angio” or “IR”
Image formed using broad beam ionizing radiation
(fluoroscopy)
Images acquired using digital detector and
processed by computer
The image formed is related to the subjects density
Usually involves the use of iodinated contrast agents
and long catheters
Many varied techniques including the use of CT or
MRI
Image display on computer or multiple films
NUCLEAR MEDICINE

High Energy Photon

Ionizing Radiation
--Radiopharmaceutical

Exposes Detector

Projection Data

Dynamic / Physiologic
Here we have an example of a nuclear
medicine bone scan with anterior and
posterior views.
Ultrasound

Also called “sono” or “echo” or “U/S”
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Image formed by transmitting and receiving high
frequency sound waves
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Image “slices” reconstructed by computation
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The image formed is related to interfaces between
tissue areas of differing sound transmission
characteristics
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Image display on computer or multiple films
Ultrasound does not involve ionizing radiation.
It uses the principle of high-frequency sound waves, which
when reflected back from structures in the body can be
converted into a grey-scale image.
Ultrasound is a real-time examination, which means that a
moving image of the body is seen on a screen, as are the
scans.
Doppler ultrasound is used to measure blood flow in
vascular structures and depends on the principle that there
is a shift in reflected sound frequency from flowing blood in
vessels.
Advantages
• Non-ionizing (no radiation)
• Safe
• Can be used to follow up
patients
• Images in real-time –
instantaneous
• Can be performed at the
bedside
• Relatively cheap
Disadvantages
• Difficult in obese patients
• Views are often obscured by
air/bowel gas
• Poor Grey-scale image
Magnetic Resonance Imaging
Also called “MRI” (used to be NMRI)
 Image formed by transmitting and receiving radio
waves inside a high magnetic field
 Image “slices” reconstructed by computation
 The image formed is related to:

 Scanner settings
 Patient hydrogen density
 Patient hydrogen chemical/physical environment

Image display on computer or multiple films
MRI is one of the newer imaging modalities that does not involve
ionizing radiation.
It involves the use of radio-waves and magnetic fields to create an
image of the body.
The patient is placed in a magnet and a radio-wave applied.
The nuclei of hydrogen atoms in water and fat absorb these waves and
emit radiofrequency energy and this can be manipulated by computer
to produce an image.
Imaging can be conducted in several planes, e.g. coronal, sagittal and
axial.
Imaging depends on the fact that pathological tissues return a
different signal to normal tissue and this property is utilized in trying
to make a diagnosis from the images.
USES - MRI
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Brain, especially pituitary, posterior fossa
Spinal cord
Musculoskeletal
Abdomen/pelvis
gynecological malignancy
liver
Contra-indications - MRI
• Pacemakers
• Metallic foreign bodies etc
• Claustrophobia
MAGNETIC RESONANCE

Hydrogen protons in a
magnetic field
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Radio wave signal
transmission
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No ionizing radiation
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Tomographic data
With magnetic resonance, the tissue response to magnetic fields and radio waves serves as the
basis for imaging. The images are slices or tomographic and the plane of section can be
determined by the machine.
Anterior
MAGNETIC
RESONANCE
R
T
EXAMPLES
 Brain
 Spine
Anterior
Posterior
Posterior
 Knee
Anterior
Posterior
Angiography
Angiography
Real time X-ray study
 Catheter placed through femoral artery is
directed up aorta into the cerebral vessels.
 Radio-opaque dye is injected and vessels are
visualized
 Gold standard for studying cerebral vessels.
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Angiography
AP Right ICA
Lateral Right ICA
AP Right Vertebral