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COMPUTED TOMOGRAPHY HISTORICAL PERSPECTIVE. OUTLINE TOMOGRAPHY – DEFINITION WHY CT – LIMITATIONS OF RADIOGRAPHY AND TOMOGRAPHY CT- BASIC PHYSICAL PRINCIPLE.

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Presentation on theme: "COMPUTED TOMOGRAPHY HISTORICAL PERSPECTIVE. OUTLINE TOMOGRAPHY – DEFINITION WHY CT – LIMITATIONS OF RADIOGRAPHY AND TOMOGRAPHY CT- BASIC PHYSICAL PRINCIPLE."— Presentation transcript:

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 DON’T 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 COMMUNICATIONS & 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

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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).FRS28 August August2004English electrical engineerNobel Prize for Physiology or MedicineAllan McLeod CormackX-ray computed tomography

17 CONSTRUCTION OF FIRST CT RADIATION SOURCE – AMERICUM GAMMA SOURCE SCAN—9 DAYS COMPUTER PROCESSING—2.5 HOURS PICTURE PRODUCTION 1 DAY

18 HOUNSFIELD’S 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 1.FIRST SCANS—20 MIN. 2.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. – SEC – 1993

26 CT SCANNING GENERATIONS

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31 HIGH SPPED CT V GENERATION ( CARDIVASCULAR CT)

32 EBCT ( SIEMENS)

33 1990 SPIRAL 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

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38 1998 MULTISLICE CT SCANNERS

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