1. IMAGE GENERATION IN CT

2. CT EXAM PROTOCOL AND PARAMETERS SELECTION PATIENT POSITIONING SCANNING
DATA RECONSTRUCTION
IMAGE DISPLAY

3. PROTOCOL AND TECHNIQUE SELECTION
PARAMETERS
SCANNING MODE
kVp mA
Time
RECONSTRUCTION
PATIENT POSITION
PATIENT ORIENTATION
SFOV
DFOV

4. PROTOCOL PEDIATRIC OR ADULT HEAD, ABDOMEN, EXTREMITIES
VASCULAR OR REGULAR

5. SCANNING MODE
AXIAL (SLICE BY SLICE)
SPIRAL (HELICAL)

6. TECHNIQUE
kVp mA
time

7. RECONSTRUCTION
SECTION THICKNESS
SECTION INDEX
ALGORITHM

8. PATIENT POSITION SUPINE OR PRONE
BODY PART UNDER SCRUTINY MUST BE PLACED IN THE ISOCENTER OF THE SCANNER

9. PATIENT ORIENTATION
HEAD FIRST
FEET FIRST

10. SFOV SCANNING FIELD OF VIEW (CALLIBRATION FIELD OF VIEW)
AREA WITHIN THE GANTRY’S ISOCENTER FROM WHICH THE RAW DATA IS ACQUIRED DURING THE SCAN. IT DEPENDS ON THE NUMBER OF DETECTORS ACTIVATED TO COLLECT DATA.

11. LARGE SFOV

12. SMALL SFOV

13. SMALL SFOV
SFOV

14. LARGE SFOV
SFOV

15. CHOOSE THE SMALLEST SFOV THAT WOULD ACCOMMODATE BODY PART FOR BEST RESOLUTION

16. IF BODY PART LIES OUTSIDE SFOV NO DATA WILL BE COLLECTED FOR THAT PART THAT EXTEND BEYOND. IT ALSO CAUSES OUT OF FIELD ARTIFACT

17. OUT OF FIELD ARTIFACT

18. DFOV – DISPLAYED FIELD OF VIEW (ZOOM OR TARGET)
DETRMINES HOW MUCH RAW DATA FROM WITHIN SFOV WILL BE UTILIZED TO CREATE AN IMAGE.

19. SFOV
DFOV

20. DISPLAYED FOV vs SCANNING FOV
DFOV CAN BE EQUAL OR LESS OF SFOV

21. DFOV VS PIXEL SIZE SMALL DFOV LARGE FOV SMALL PIXEL LARGE PIXEL
LARGE DFOV
LOW SPATIAL RESOLUTION
LOW VISIBILITY OF DETAIL

22. LARGE DFOV

24. SMALL DFOV

32. DFOV

33. DFOV

37. PIXEL SIZE= DFOV (mm)/ MATRIX SIZE

38. SAMPLE

39. SCANNING
TOPOGRAM
REGULAR SCAN

40. TOPOGRAM (SCOUT)
TUBE DOES NOT REVOLVE AROUND THE PATIENT

41. AP SCOUT
TUBE
TUBE SUSPENDED ABOVE PATIENT DURING SCOUT GENERATION

42. LAT SCOUT
TUBE AT THE 90º ANGLE TO PATIENT

43. REGULAR SCAN

44. I, II, AND III GENERATION
CONTINUOUS DATA ACQUSITION GEOMETRY

45. IV GENERATION
STATIONARY DATA ACQUSITION GEOMETRY

46. REGULAR SCAN
AXIAL (CONVENTIONAL, SLICE-BY-SLICE)
SPIRAL

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

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

49. TOTAL NUMBER OF TRANMISSION MEASUREMENT EQUALS NUMBER OF VIEWS X NUMBER OF RAYS IN EACH VIEW

51. ACQUSITION TERMINOLOGY
RAY
VIEW
PROFILE

52. PART OF THE X-RAY BEAM THAT FALLS ON ONE DETECTOR

53. COLLECTION OF THE RAYS FOR ONE TRANSLATION ACROSS THE OBJECT
VIEW
COLLECTION OF THE RAYS FOR ONE TRANSLATION ACROSS THE OBJECT

54. ANALOG SIGNAL GENERATED IN A VIEW
PROFILE
ANALOG SIGNAL GENERATED IN A VIEW

55. RAY
VIEW
PROFILE

57. RECONSTRUCTION
DATA THAT HAVE BEEN BACKPROJECTED INTO THE IMAGE MATRIX TO CREATE CT IMAGES DISPLAYED ON THE MONITOR

58. RECONSTRUCTION TRANSMISSION MEASUREMENT (LINEAR ATTENUATION COEFFICIENT) IS CONVERTED INTO CT NUMBER (HOUNSFIELD UNIT) Ц
CT #
RECONSTRUCTION

59. LINEAR ATTENUATION COEFFICIENT ( cm-1)
BONE
BLOOD
G. MATTER
W. MATTER
CSF
WATER
FAT
AIR

60. CT NUMBER CALCULATION

61. CT NUMBER SCALE WATER – 0 BASELINE CORTICAL BONE +1,000 MUSCLE +50
WHITE MATTER +45
GRAY MATTER +40
BLOOD +20
CSF +15
FAT
LUNG -200
AIR -1,000
APPEARS WHITE
GRAY
LIGHT GRAY
DARK GRAY TO BLACK
WATER – 0 BASELINE

62. CT # vs BRIGHTNESS LEVEL
+ 1000
-1000

63. CT #
+400

64. CT #
+500

65. CT #
+40

66. CT #
+15

67. CT #
- 200

68. CT # OF CYST

69. CT # OF LIPOMA ( FATTY TUMOR)
                                                                                                                        
-100

70. CT #
-100