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COMPUTED TOMOGRAPHY HISTORICAL PERSPECTIVE

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Title: COMPUTED TOMOGRAPHY HISTORICAL PERSPECTIVE


1
COMPUTED TOMOGRAPHY HISTORICAL PERSPECTIVE
2
OUTLINE
  • TOMOGRAPHY DEFINITION
  • WHY CT LIMITATIONS OF RADIOGRAPHY AND
    TOMOGRAPHY
  • CT- BASIC PHYSICAL PRINCIPLE
  • HISTORICAL TRAIL
  • CT GENERATIONS

3
Tomography From the Greek word tomos section.
The process for generating a tomogram, a
two-dimensional image of a section through a
three-dimensional object. Tomography achieves
this result by simply moving an x-ray source in
one direction as the x-ray film is moved in the
opposite direction during the exposure to sharpen
structures in the focal plane, while structures
away from the focal plane appear blurred.
4
CONVENTIONAL RADIOGRAPHY HAS LIMITATIONS
  • TWO DIMENSIONAL IMAGE WITH INFINITE DEPTH -
    SUPERIMPOSITION OF UNDERLYING STRUCTURES (LATERAL
    AND OBLIQUE VIEWS DONT SOLVE IT COMPLETELY).
  • INABILITY TO DEMONSTRATE SLIGHT DIFFERENCES IN
    SUBJECT CONTRAST CHARACTERISTIC OF SOFT TISSUE.

5
TOMOGRAPHY SOLUTION?
  • CONVENTIONAL TOMOGRAPHY ATTEMPTED TO ELIMINATE
    THE SUPERIMPOSITION PROBLEM BY BLURRING THE
    STRUCTURES ABOVE AND BELOW THE TOMOGRAPHIC FOCAL
    PLANE.
  • CONTRAST OF AN IMAGE CAN ALSO BE CHANGED BY
    VARYING TOMOGRAPHIC ANGLE (DISTANCE OF A TUBE
    TRAVEL)
  • MULTIDIRECTIONAL TUBE MOVEMENT MAKES THE BLURRING
    OF UNWANTED STRUCTURES EVEN MORE EFFECTIVE.

6
TOMOGRAPHY STILL LIMITED
  • IMAGE BLURR PRESENT
  • EXCESSIVE SCATTER RADIATION FILM FOG

7
RADIOGRAPHY AND TOMOGRAPHY
  • TISSUE DIFFERENCE SENSITIVITY
  • 5-10

8
CT GOALS
9
CT EVOLUTION OF TERMS
COMPUTERIZED TRANSVERSE AXIAL TOMOGRAPHY
COMPUTER ASISSTED TOMOGRAPHY
COMPUTERIZED AXIAL TOMOGRAPHY
COMPUTED TOMOGRAPHY
10
FORMATION OF CT IMAGE
DATA AQUSITION
IMAGE RECONSTRUCTION
IMAGE DISPLAY, MANIPULATION, STORAGE COMMUNICATIO
NS RECORDING
11
DATA ACQUISITION
  • COLLECTION OF X-RAY PHOTONS TRANSMITTED THROUGH
    THE PATIENT BY THE CT DETECTORS.

12
DETECTORS
13
IMAGE RECONSTRUCTION
  • TRANSMISSION MEASUREMENTS COLLECTED BY THE CT
    DETECTORS ARE SENT TO THE COMPUTER FOR THE
    PROCESSING. COMPUTERS USES MATHEMATICAL ALGORITHM
    TO RECONSTRUCT THE IMAGE.

14
IMAGE DISPLAY, MANIPULATION, STORAGE,
COMMUNICATION.
  • AFTER RECONSTRUCTION IMAGE CAN BE DISPLAYED ON
    THE MONITOR
  • IMAGE CAN BE MANIPULATEDIMAGE CAN BE STORED ON
    MOD OR CD.
  • DURING COMMUNICATION PHASE IMAGE MAY BE
    TRANSMITTED TO A REMOTE LOCATION

15
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16
Sir Godfrey Newbold Hounsfield CBE, FRS, (28
August 1919 12 August 2004) was an English
electrical engineer who shared the 1979 Nobel
Prize for Physiology or Medicine with Allan
McLeod Cormack for his part in developing the
diagnostic technique of X-ray computed tomography
(CT).
17
CONSTRUCTION OF FIRST CT
  • RADIATION SOURCE AMERICUM GAMMA SOURCE
  • SCAN9 DAYS
  • COMPUTER PROCESSING2.5 HOURS
  • PICTURE PRODUCTION 1 DAY

18
HOUNSFIELDS LATHE BED SCANNER
19
DR.HOUNSFIELD DR. AMBROSE
  • READINGS FROM SPECIMEN OF HUMAN BRAIN. TUMOR
    FINDINGS APPARENT.

20
1972
  • FIRST CLINICAL PROTOTYPE CT BRAIN SCANNER
  • FIRST SCANS20 MIN.
  • LATER REDUCED TO 4.5 MIN.

21
CLINICALLY USEFUL CT SCANNER
22
DR. HOUNSFIELD
  • 1972 McROBERT AWARD
  • 1979 NOBEL PRIZE

23
ALLAN M. CORMACK
  • 1979 NOBEL PRIZE SHARED WITH DR. HOUNSFIELD.
    DEVELOPED SOLUTIONS TO MATHEMATICAL PROBLEMS IN
    CT.

24
1974
  • DR. ROBERT LEDLEY DEVELOPED THE FIRST WHOLE BODY
    CT SCANNER .

25
SCANNING DEVELOPMENT
  • 5 MIN. 1972
  • 1 SEC 1993

26
CT SCANNING GENERATIONS
27
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28
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31
HIGH SPPED CT V GENERATION ( CARDIVASCULAR CT)
32
EBCT ( SIEMENS)
33
1990SPIRAL CT ( HELICAL) SLIP RING TECHNOLOGY
34
CT SCANNING IN SPIRAL-HELICAL GEOMETRY BASED ON
SLIP RING TECHNOLOGY
Slip rings
35
SCANNER POWER SUPPLY-SLIP RINGS DISK
36
1992
  • DUAL SLICE CT HELICAL SCANNER

37
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38
1998
  • MULTISLICE CT SCANNERS

39
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