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DIGITAL PROJECTION RADIOGRAPHY COMPUTED RADIOGRAPHY

DIGITAL PROJECTION RADIOGRAPHY COMPUTED RADIOGRAPHY. DIGITAL PROJECTION RADIOGRAPHY DEPENDS ON COMPUTER TECHNOLOGY TO PRODUCE DIGITAL RADIOGRAPHIC IMAGE. DIGITAL PROJECTION RADIOGRAPHY. COMPUTED RADIOGRAPHY (CR). DIGITAL RADIOGRAPHY (DR). DIGITAL RADIOGRAPHY vs COMPUTED RADIOGRAPHY. DR.

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DIGITAL PROJECTION RADIOGRAPHY COMPUTED RADIOGRAPHY

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  1. DIGITAL PROJECTION RADIOGRAPHYCOMPUTED 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 vsCOMPUTED RADIOGRAPHY

  5. DR X-RAYS DETECTORS ADC 11011101

  6. CR X-RAYS CR PLATE SCANNER ADC 11011101

  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)

  9. CR PLATE

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

  11. CR CASSETTES ARE NOT LIGHT-TIGHTIMAGE PLATE IS NOT SENSITIVE TO LIGHT

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

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

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

  15. REMOTE OPERATOR PANEL

  16. IMAGE PLATE APPROX. 1MM

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

  18. BASE • PET- POLYETHYLENE TERAPHTALATE

  19. PHOSPHOR LAYER • Ba FX: Eu +2

  20. PROTECTIVE LAYER • FLUORINATED POLYMER MATERIAL PROTECTS PHOSPHOR LAYER

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

  22. BACKING LAYER • PROTECTS THE BASE FROM DAMAGE.

  23. LEAD COATING SCATTER

  24. 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).

  25. 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

  26. The shifting of europium from its excited state back to its ground state for both spontaneous and photostimulated luminescence is about 0.6 - 0.8 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.

  27. 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.

  28. 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.

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

  30. 25% OF STORED ENERGY WITHIN 8 HOURS FADING

  31. CR AFTER EXPOSURE IS INSERTED INTO CR SCANNER

  32. CR PLATE CR SCANNER/READER

  33. THE SCANNER SCANS THE IMAGE PLATE WITH LASER LIGHT AND READS THE LATENT IMAGE FROM THE PHOSPHORREADOUT

  34. LASER LIGHTHELIUM-NEON (633 nm) LASER BEAM SWEEPS THE PLATE IN RASTER FASHION

  35. RASTER

  36. LASER PM TUBE LIGHT GATE AMPLIFIER ADC

  37. SWEEPING OF THE LASER ACROSS THE PLATE • FAST SCAN DIRECTION • SCAN DIRECTION • LASER SCAN DIRECTION

  38. PLATE MOVEMENT IN THE SCANNER • SLOW SCAN DIRECTION • SUB-SCAN DIRECTION • PLATE SCAN DIRECTION

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

  40. LASER 633 nm PHOTOSTIMULABLE LUMINESCENCE 390-400 nm PLATE & F-CENTERS

  41. LASER LASER SPOT SIZE - 100 MICROMETERSPIXEL SIZE - 100 MICROMETERS

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

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

  44. Typical image plate can be reused thousands of times

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