Introduction to Medical Imaging

Chapter 1: Introduction
13 November 2016 1
Hossain Md Shakhawat
Department of Information Processing
Tokyo Institute of Technology
Digital Image Processing -3rd Edition by Rafael C.
Gonzalez, Richard E. Woods
One picture is worth more than ten thousand words

Objectives of the chapter
 Introduction to Digital image processing (DIP)
 Define the scope of DIP
 Historical background
 Introduce the application areas
 Introduce the principle approaches of DIP
 Components of image processing
 Provide directions to the book
2

What is Image ?
 Mathematically, Image is a two dimensional function f(x,y) where the x and
y are spatial co-ordinates and the amplitude of function “ f ” at any pair of
co-ordinates (x,y) is called the intensity of the image at that point.
3
 Analog Image: when x, y and the amplitude
values of f are continuous quantities
 Digital Image: when x, y and the amplitude
values of f are all finite and discrete
quantities.
Digital image is composed of finite number of elements called pixels,
each of which has a particular location and intensity value.

Digital Image Processing
 DIP is the processing of digital image in a digital manner meaning that
is using a digital device like digital computer.
 Two major application areas:
1. Improvement of pictorial information for human interpretation.
2. Processing of image data for storage, transmission and
representation for autonomous machine perception
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Digital Image Digital Computer
+
Digital Image
Processing

Level of Image Processing
5
Image to image transformation
Low
Level
Image to attribute transformation
Mid Level
Attribute to image transformation
High Level
Information
about
Attributes
Input Process Output

6
Post ProcessingRevealed Underplayed
Information
Advantages of Digital
Image Processing
Applications of
Digital Technology

Origin and Evolution of DIP
DIP technology evolved with the advancement in digital computers
 1920 -> Bartline cable system reduced the time for transmission from week to hours
 1921 -> pictures were produced from a coded tape by telegraph printers
 1922 -> Improvements in the reproduction system increased visual quality
 1929 -> Number of gray levels increased to 15 from 5
 1940 -> Invention of modern digital computer
 1940 to 1960 -> Development of transistors, IC, programming language, operating
system and microprocessor made the computer efficient enough for DIP.
 1960 -> First use of computer to correct images of moon
 1970 -> Early applications in medical imaging
 1980 to till date -> Enabled the modality of image analysis and computer vision
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Pictures were sent using submarine cable for news

Application Fields
 Unlike the humans who are limited to visible band of electromagnetic
spectrum (EM), the imaging machines cover almost the entire EM
spectrum from gamma to radio waves.
 Thus DIP encompasses a wide and diverse fields of applications that
human are not accustomed to.
 One efficient way is to analyze the fields based on the sources of image:
 Gamma ray imaging
 X-ray Imaging
 Ultraviolet imaging
 Imaging in visible and infrared bands
 Imaging in microwave band
 Imaging in radio band
8

 Based on gamma rays. Includes nuclear medicine(i.e. bone pathology, PET) and
astronomical observations.
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Nuclear Medicine:
1. Radioactive isotope is injected into body
2. Isotope emits gamma rays as it decays
3. Images are produced from the emissions,
collected by gamma ray detector.
Examples: Bone scanning, Positron emission
tomography (PET)
1. Bone Scan 2. PET Image
Astronomical observation:
• A star in the constellation area of Cygnus exploded
thousands years ago. This generated the superheated
gas cloud called Cygnus loop cloud, that glows in a
spectacular array of colors.
• Unlike the above two (1 & 2) this image (3) was obtained
using the natural radiation of the object.
3. Cygnus loop of gas cloud

10
• Imaging with X-rays:
1. An X-ray beam produced by X-ray tube passes through the
body.
2. On it’s way through the body, parts of the energy of the X-ray
beam are absorbed, called attenuation of the X-ray beam.
3. On the opposite side of body, detectors or a film capture the
attenuated X-rays, resulting in a clinical 2D image.
4. In Computed Tomography, the tube and the detector are both
rotating around the body so that multiple images can be
acquired for 3D visualization.
• Examples: Medical (X-ray radiography, computed tomography
(CT), mammography, angiography and fluoroscopy) and
industrial imaging.
1. Radiography of chest
2. CT scan of head

11
• The ultraviolet light is not visible but it offers
a wide area of applications: lithography,
industrial inspection, fluorescence
microscopy, lasers, biological imaging and
astronomical observations.
1. Smut Corn Detection
Left: Normal Corn Right: Smut Corn
2. Mouse Brain Tissue Section
[ Source: http://www.microscopyu.com/galleries/fluorescence/index.html ]

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• Infrared imaging has the unique
capability to observe sources of faint
sources of visible-near infrared
emissions of the earth surface including
cities, villages, gas flames and fires.
• Offers extreme level remote sensing and
also in medical science
1. Satellite image of hurricane Katrina
2. photography
• Imaging in the visible band

13
• Radar imaging provides its own illumination (microwave pulses) to illuminate the
subject and capture the image.
• Instead of using lens it uses an antenna and digital computer to record or
capture the image.
• Major application: radar imaging
• Radar imaging can collect data of any
region without regarding the
weather or ambient light conditions.
• It can penetrate clouds.
1. Radar image of Tibet mountain

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• Like the other end (gamma ray) of spectrum
major applications of radio band are also
medicine and astronomy. Ex: MRI (Magnetic
resonance imaging ).
• MRI is Safer than CT
• MRI:
1. Places the patient in a powerful magnet and
passes radio waves through the body in
short pulses.
2. Each pulse causes a responding pulse of
radio waves to be emitted by the body (H2).
3. Location and strength of these signals is
captured to form the 3D image

Others
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1. TEM Image of Polio Virus
2. Ultrasound image of Unborn
Baby
3. SEM Image of Polen Grains
1 2
3

Components of DIP System
16
Image
Displays
Computer Mass Storage
Hardcopy
Special Image
Processing
Hardware
Image
Processing
Software
Image
Sensors
Network
Problem Domain

Directions for the rest of the book
17

Introduction to Medical Imaging

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