1. DIGITAL PROJECTION RADIOGRAPHY COMPUTED RADIOGRAPHY

2. DIGITAL PROJECTION RADIOGRAPHY DEPENDS ON COMPUTER TECHNOLOGY TO PRODUCE DIGITAL RADIOGRAPHIC IMAGE

3. DIGITAL PROJECTION RADIOGRAPHY
COMPUTED RADIOGRAPHY (CR)
DIGITAL RADIOGRAPHY (DR)

4. DIGITAL RADIOGRAPHY vs COMPUTED RADIOGRAPHY

5. DR
X-RAYS
DETECTORS
ADC

6. CR
X-RAYS
CR PLATE
SCANNER
ADC

7. COMPUTED RADIOGRAPHY (CR): USES PHOTOSTIMULABLE PLATE (IMAGE PLATE) INSTEAD OF FILM, AS THE IMAGE RECEPTOR. CR USES CASSETTE THAT LOOKS VERY SIMILAR TO CONVENTIONAL RADIOGRAPHIC CASSETTE.

8. CR PLATE !!!!! DOES NOT USE SCREENS OR FILM ( CONVENTIONAL FILM)

10. CR PLATE

11. FRONT PANEL MADE OF LOW ATTENUATION
CASETTE CONSTRUCTION
LIGHTWEIGHT ALUMINUM
PLASTIC
STEEL FRAME
FRONT PANEL MADE OF LOW ATTENUATION
CARBON FIBER

12. CR CASSETTES ARE NOT LIGHT-TIGHT IMAGE PLATE IS NOT SENSITIVE TO LIGHT

13. CR CASSETTE IS PROTECTING IMAGE PLATE FROM DAMAGE + IS THE STABLE VEHICLE FOR TRANSPORT AND PLACEMENT OF THE CASSETTE UNDER THE PATIENT

14. BACK PANEL CONTAINS LEAD FOIL TO PROTECT THE PLATE FROM BACKSCATTER

15. BACK PANEL ALSO CONTAINS CHIP TO RECORD PATIENT DEMOGRAPHIC INFORMATION

16. REMOTE OPERATOR PANEL

20. IMAGE PLATE
APPROX. 1MM

21. CROSS-SECTION OF CR PLATE
PROTECTIVE LAYER
PHOSPHOR LAYER
ANTI-HALO & REFLECTIVE LAYER
BASE
BACKING LAYER

22. BASE
PET- POLYETHYLENE TERAPHTALATE

23. PHOSPHOR LAYER
Ba FX: Eu +2

24. PROTECTS PHOSPHOR LAYER
PROTECTIVE LAYER
FLUORINATED POLYMER MATERIAL
PROTECTS PHOSPHOR LAYER

25. ANTI-HALO LAYER + REFLECTIVE LAYER
PREVENTS LASER FROM PASSING THROUGH.
REFLECTED LIGHT FROM PHOSPHOR IS ALLOWED TO PASS.

26. BACKING LAYER
PROTECTS THE BASE FROM DAMAGE.

27. LEAD COATING
SCATTER

28. The simplest explanation for luminescence is that impurities in the crystal lattice are responsible for luminescence. As the concentration of impurity ions increase the greater the intensity of the luminescence. CR screens use barium fluorohalides doped with europium (europium is the impurity in the crystal).

29. When phosphors are stimulated with x-ray photon energy electron pair holes are created. In effect, europium is raised to an excited state and upon luminescence it is returned to its ground Eu2+ state. This mechanism holds for both spontaneous luminescence and photostimulated luminescence

30. The shifting of europium from its excited state back to its ground state for both spontaneous and photostimulated luminescence is about microseconds. With screen-film imaging these crystals spontaneously luminescence to expose a film, but with CR imaging the luminescence occurs, then there is also photoluminescence that occurs when the screen is stimulated by a narrow beam of infrared light.

31. The holes or vacancies in the lattice are portions of the lattice normally occupied by halogens (fluoride, bromide, or iodine). These vacancies will trap free electrons when irradiated and are called Farbzentren centers or F-centers.

32. When the photostimulable plate is exposed to high frequency light, usually from a helium laser, the electrons in these F-centers are liberated and cause luminescence at readout.

33. THE LATENT IMAGE WILL REMAIN STORED FOR 24 HOURS
THE LATENT IMAGE WILL REMAIN STORED FOR 24 HOURS. IT WILL FADE THROUGH PHOSPHORESCENCE

34. FADING
25% OF STORED ENERGY
WITHIN 8 HOURS

35. CR AFTER EXPOSURE IS INSERTED INTO CR SCANNER

36. CR PLATE
CR SCANNER/READER

37. THE SCANNER SCANS THE IMAGE PLATE WITH LASER LIGHT AND READS THE LATENT IMAGE FROM THE PHOSPHOR READOUT

38. LASER LIGHT HELIUM-NEON (633 nm) LASER BEAM SWEEPS THE PLATE IN RASTER FASHION

40. RASTER

41. LASER
PM TUBE
LIGHT
GATE
AMPLIFIER
ADC

42. SWEEPING OF THE LASER ACROSS THE PLATE
FAST SCAN DIRECTION
SCAN DIRECTION
LASER SCAN DIRECTION

43. PLATE MOVEMENT IN THE SCANNER
SLOW SCAN DIRECTION
SUB-SCAN DIRECTION
PLATE SCAN DIRECTION

44. THE SPEED OF THE SCANNING LASER BEAM IS ADJUSTED TO THE LUMINESCENT SIGNAL

45. PHOTOSTIMULABLE LUMINESCENCE
LASER 633 nm
PHOTOSTIMULABLE LUMINESCENCE nm
PLATE & F-CENTERS

46. LASER LASER SPOT SIZE - 100 MICROMETERS PIXEL SIZE - 100 MICROMETERS

47. P.M. TUBE DETECTION SENSITIVITY MATCHED TO BLUE-PURPLE PSL (390-400 nm)

48. AFTER SCANNING THE CR PLATE NEED TO BE CLEARED FROM RESIDUAL SIGNAL PLATE EXPOSED TO HIGH INTENSITY SODIUM VAPOR OR FLUORESCENT LIGHT

50. Typical image plate can be reused thousands of times

51. IMAGE DISPLAY

52. IMAGE CHECK-INDEX???

53. IMAGE MANIPULATION-WINDOWING

54. PICTURE DESTINATION -PACS

55. PACS

56. CR CHARACTERISTIC CURVE
VERY WIDE LATITUDE

57. CR SYSTEMS
LESS RADIOGRAPH REPEATS

58. CHARACTERISTIC CURVE
LATITTUDE OF FILM
LATITTUDE OF CR

59. IMAGE CAN BE SALVAGED WITH CR
500% OVEREXPOSURE
80% UNDEREXPOSURE
USE ADEQUATE KVP

60. HARD COPY GENERATED IN LASER PRINTER

61. CR SYSTEM EFFICIENCY CHARACTERISTIC
QDE- QUANTUM DETECTION EFFICIENCY
NO NEED FOR SCREENS

62. QDE: THE MEASURE OF THE EFFICIENCY OF CR SYSTEM TO CONVERT REMNANT X-RAYS TO USEFUL IMAGE SIGNAL

63. QDE PATIENT DOSE

64. DIGITAL RADIOGRAPHY

65. ELECTRONIC DETECTORS
INDIRECT TECHNIQUE CLASS
DIRECT TECHNIQUE CLASS

66. INDIRECT TECHNIQUE INDIRECT CONVERSION FLAT PANEL DETECTORS
INDIRECT CONVERSION CHARGED COUPLE DEVICE DETECTORS

67. INDIRECT CONVERSION FLAT PANEL DETECTORS
USE THIN LAYERS OF SILICON COMBINED WITH THE ARRAYS OF PHOTODIODES. P.D. IS COATED WITH CESIUM IODIDE OR RARE EARTH MATERIAL- WHEN STRUCK BY REMNANT X-RAYS THEY EMIT LIGHT.
ADVANTAGE: HIGH QDE
DISADVANTAGE: LIGHT DIVERGENCE

68. PHOTODIODE

70. INDIRECT CONVERSION CHARGE COUPLED DEVICE DETECTORS
USE CCD ARRAYS TO RECORD THE VISIBLE LIGHT EMITTED BY A SCINTILLATION CRYSTAL THAT HAS ABSORBED THE ENERGY. AN OPTICAL COUPLING SYSTEM DEMAGNIFIES THIS LIGHT AND SENDS IT TO THE CCD ARRAY.

71. OPTICAL COUPLING

72. CCD

73. DIRECT TECHNIQUE
DIRECT CONVERSION FLAT PANEL DETECTORS

74. DIRECT CONVERSION FLAT PANEL DETECTORS
USE AN AMORPHOUS SELENIUM COATED THIN FILM TRANSISTOR ARRAY THAT DIRECTLY CONVERTS X-RAY ENERGY INTO ELECTRICAL SIGNAL. REMNANT X-RAYS ARE ABSORBED IN THE SELENIUM WHERE THEY FORM ELECTRON-HOLES. CAPACITORS COLLECT THE CHARGE.
ADVANTAGE: NO LIGHT DIVERGENCE

75. READY - The 17"x17" amorphous selenium-based sensor is electrically sensitized and readied for exposure.
                                                                           
EXPOSE - Incident X-ray photons are converted into electron-hole pairs. A transverse electric field separates the electrons and holes and creates a charge image precisely corresponding to the X-ray image.
READOUT - The microplasma line scanner sweeps across the sensor in less than 2 seconds causing readout of the charge image and sensor reset.

76. DR vs CR COMPARISON DR SYSTEM IMMEDIATE REDOUT CASSETTE FREE OPERATION
ADVANTAGE
DISADVANTAGE
IMMEDIATE REDOUT
CASSETTE FREE OPERATION
GOOD FOR HIGH VOLUME RADIOGRAPHY
CAN BE USED FOR MAMMOGRAPHY
DETECTORS CAN BE RE-EXPOSED IMMEDIATELY
MORE EXPENSIVE
CAN NOT BE USED IN PORTABLE RADIOGRAPHY??????
NOT COMPATIBLE WITH EXISTING TABLES

78. PORTABLE????

79. PORTABLE CT???!!

81. 4K MONITORS USED IN MAMMOGRAPHY
MONITORS IN DR 1K 2K 4K
1,000 X 1,000 PIXELS
2,000 X 2,000 PIXELS
4,000 X 4,000 PIXELS
4K MONITORS USED IN MAMMOGRAPHY
AND CHEST RADIOGRAPHY

82. DR TERMS TO KNOW PIXEL VOXEL SPATIAL RESOLUTION DYNAMIC RANGE
CONTRAST RESOLUTION
IMAGE NOISE

83. PIXEL

84. .
                                                                                                                  
VOXEL
The formation