Presentation is loading. Please wait.

Presentation is loading. Please wait.

PRINCIPLES OF CT. TOMOGRAPHY TOMOS---SECTION RADIOGRAPHY LIMITATIONS SUPERIMPOSITION DIFFICULTY IN DISTINGUISHING BETWEEN HOMOGENOUS OBJECTS OF NON-UNIFORM.

Similar presentations


Presentation on theme: "PRINCIPLES OF CT. TOMOGRAPHY TOMOS---SECTION RADIOGRAPHY LIMITATIONS SUPERIMPOSITION DIFFICULTY IN DISTINGUISHING BETWEEN HOMOGENOUS OBJECTS OF NON-UNIFORM."— Presentation transcript:

1 PRINCIPLES OF CT

2 TOMOGRAPHY TOMOS---SECTION

3 RADIOGRAPHY LIMITATIONS SUPERIMPOSITION DIFFICULTY IN DISTINGUISHING BETWEEN HOMOGENOUS OBJECTS OF NON-UNIFORM THICKNESS.

4 SUPERIMPOSITION

5 RADIOGRAPHY LIMITATIONTISUE DIFFERENCE SENSITIVITY >10%

6 TOMOGRAPHY (CONVENTIONAL) ELIMINATES TISSUE SUPERIMPOSITION INCREASES CONTRAST OF LOW SUBJECT CONTRAST TISSUES

7 TOMOGRAPHY

8

9 TOMOGRAPHY LIMITATIONS MOTION BLURR

10 CT ADVANTAGES

11 LIMITATIONS OF CT UNABLE TO DIFFERENTIATE BETWEEN TISSUES WITH SLIGHT CONTRAST DIFFERENCES < 1%.

12

13 GOALS OF CT MINIMAL SUPERIMPOSITION IMAGE CONTRAST IMPROVEMENT SMALL TISSUE DIFFERENCE RECORDING

14 CT DATA AQUISITION

15

16 TRANSMISSION RELATIVE TRANSMISSION=Io/I

17 HISTORY OF CT

18 Sir Godfrey Newbold Hounsfield CBE (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).

19 HOUNSFIELDS SKETCH

20 CONSTRUCTION OF FIRST CT RADIATION SOURCE – AMERICUM GAMMA SOURCE SCAN9 DAYS COMPUTER PROCESSING2.5 HOURS PICTURE PRODUCTION 1 DAY

21 HOUNSFIELDS LATHE BED SCANNER

22 1972 FIRST CLINICAL PROTOTYPE CT BRAIN SCANNER 1.FIRST SCANS20 MIN. 2.LATER REDUCED TO 4.5 MIN.

23 CLINICALLY USEFUL CT SCANNER

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

25 SCANNER GENERATIONS I II III IV

26 180 DEG ROTATION

27

28 360 DEG ROTATION

29

30 MODERN SCANNER

31 CT MAIN SYSTEMS IMAGING SYSTEM COMPUTER SYSTEM DISPLAY, RECORDING, STORAGE SYSTEM DATA ACQUISITION SYSTEM

32 IMAGING SYSTEM PRODUCTION OF X-RAYS SHAPING OF X-RAY BEAM ENERGY FILTERING X-RAY BEAM

33 SCANNER GANTRY TABLE/COUCH

34 GANTRY INSIDE

35 COMPUTER SYSTEM RECONSTRUCTION AND POSTPROCESSING CONTROL OF ALL SCANNER COMPONENTS CONTROL OF DATA ACQUSITION, PROCESSING, DISPLAY. DATA FLOW DIRECTION

36 COMPUTER SYSTEM IN CT MINICOMPUTERS

37 IMAGE DISPLAY, RECORDING, STORAGE DISPLAYS IMAGE ( OUTPUT FROM COMPUTER) PROVIDES HARD COPY OF THE IMAGE FACILITATES THE STORAGE AND RETRIEVAL OF DIGITAL DATA COMMUNICATES IMAGES IN THE NETWORK

38 DATA ACQUISITION SYSTEM (DAS) SET OF ELECTRONICS BETWEEN DETECTORS AND HOST COMPUTER.

39 CT COMPONENTS GANTRY TABLE/COUCH COMPUTER CONSOLE

40 ORIGINAL CLINICAL CT SCANS COMPOSED OF 80 X 80 MATRIX PIXELS 6400

41 EARLY DAYS vs TODAY 80 x x 512

42 COORDINATE SYSTEM IN CT X

43 Y

44 Z

45 ISO-CENTER

46

47 SCAN FOV SFOV DETECTORS

48 DFOV – DISPLAYED FIELD OF VIEW SIZE DISPLAYED ON THE MONITOR

49 PIXEL SIZE PIXEL SIZE= DFOV (mm)/ MATRIX SIZE

50 RECONSTRUCTION Ц CT # RECONSTRUCTION

51 PIXEL vs VOXEL PIXEL VOXEL

52 PIXEL SIZE DEPENDS ON: MATRIX SIZE FOV

53 VOXEL SIZE DEPENDS FOV MATRIX SIZE SLICE THICKNESS

54 IMAGE DISPLAY

55 IN CT DIGITAL RECONSTRUCTED IMAGE IS CONVERTED IMAGE IS CONVERTED INTO A GRAY SCALE IMAGE.

56

57

58 CT # vs BRIGHTNESS LEVEL

59 CT # 1000

60 CT # - 500

61 CT # OF CYST 5

62 CT # OF LIPOMA ( FATTY TUMOR) -100

63

64 SCANNING

65 TECHNIQUE kVp mA TIME SLICE THICKNESS SLICE INCREMENTATION

66 PATIENT ORIENTATION HEAD FIRST FEET FIRST

67

68 SCANNING TOPOGRAM REGULAR SCAN

69 TOPOGRAM (SCOUT) TUBE DOES NOT REVOLVE AROUND THE PATIENT

70 AP SCOUT TUBE SUSPENDED ABOVE PATIENT DURING SCOUT GENERATION TUBE

71 LAT SCOUT TUBE AT THE 90º ANGLE TO PATIENT

72 AXIAL SCAN TABLE STOPS AT THE SCANNING POSITION AND THE TUBE ROTATES AROUND A PATIENT.

73 SPIRAL PATIENT CONTINUOUSLY MOVES IN THE Z-AXIS DIRECTION WHILE THE TUBE ROTATES AROUND.

74 CONVENTIONAL AND SPIRAL/HELICAL CT

75 ADVANTAGE OF SPIRAL IMAGING OVER CONVENTIONAL SPEED

76 CT SPECIAL APPLICATIONS

77 CARDIAC ANGIOGRAPHY

78 VIRTUAL ENDOSCOPY

79 RADIATION TREATMENT

80 3D IMAGING

81


Download ppt "PRINCIPLES OF CT. TOMOGRAPHY TOMOS---SECTION RADIOGRAPHY LIMITATIONS SUPERIMPOSITION DIFFICULTY IN DISTINGUISHING BETWEEN HOMOGENOUS OBJECTS OF NON-UNIFORM."

Similar presentations


Ads by Google