Cr & dr

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Comparative Study of CR and DR

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Cr & dr

  1. 1. Dr. Muhammad bin zulfiqar PGR-1 SIMS/ SHL.
  2. 2. Basics of Digital Language
  3. 3. 5 Byte The basic unit of binary coded information Kilobyte—210 – 1024 bites Megabyte—1024 times1024bites
  4. 4. Performance parameters Pixel: Smallest complete sample of an image. Has a varied set of tones in shades of white/ black/grey. Expressed in binary codes (bits). Size of the pixel : Smaller the size , better resolution. CR- 50 to 200 microns, DR- 100 to 200 microns, DM- 50 to 100 microns. Gray Scale: Shades of Gray in between pure black and pure white. Bit Depth: No of shades to define each pixel ,measured as no of bits. Larger the depth, incr gray scale and large file size.
  5. 5. Spatial Resolution: finer details, diff objects in an image. Depends on sampling frequency and no of pixels. expressed in lp/mm. Contrast Resolution: Color or gray scale differentiation. Indicate the no of shades of grey that a detector can capture. File Size. Performance Parameters(contd..)
  6. 6. DIGITAL PROJECTION RADIOGRAPHY COMPUTED RADIOGRAPHY (CR) DIGITAL RADIOGRAPHY (DR)
  7. 7. 11011101 CR X-RAYS CR PLATE SCANNER
  8. 8. DETECTORS 11011101 DR X-RAYS
  9. 9. Computed Radiography (CR) Been around since 1980-81 Uses same radiographic equipment No change in X-ray machine Uses an imaging plate Contains a photostimulator phosphor Need a cassette reader Images can be sent to a PACS
  10. 10. Computed Radiography (CR) Re-usable metal imaging plates replace film & cassette Uses conventional bucky & x-ray equipment                                                                  
  11. 11. CR SYSTEM COMPONENTS CASSETTES (phosphor plates) ID STATION IMAGE PREVIEW STATION DIGITIZER VIEWING STATION
  12. 12. CR PLATE
  13. 13. CASETTE CONSTRUCTION LIGHTWEIGHT ALUMINUM PLASTIC STEEL FRAME FRONT PANEL MADE OF LOW ATTENUATION CARBON FIBER
  14. 14. PROTECTIVE LAYER PHOSPHOR LAYER ANTI-HALO & REFLECTIVE LAYER BASE BACKING LAYER
  15. 15. PHOSPHOR LAYER BASE Ba FX: Eu +2 PET- POLYETHYLENE TERAPHTALATE PROTECTIVE LAYER FLUORINATED POLYMER MATERIAL PROTECTS PHOSPHOR LAYER
  16. 16. ANTI-HALO LAYER + REFLECTIVE LAYER PREVENTS LASER FROM PASSING THROUGH. REFLECTED LIGHT FROM PHOSPHOR IS ALLOWED TO PASS. BACKING LAYER PROTECTS THE BASE FROM DAMAGE.
  17. 17. SCATTER
  18. 18. REMOTE OPERATOR PANEL
  19. 19. CR Operation
  20. 20. Add module code number and lesson title 29
  21. 21. Add module code number and lesson title 30 The principle of PSP Excitation Storage Emission CB Trap ADC PMT
  22. 22. Higher Energy Electron State Lower Energy Electron State - - - - - - - - - - - - - - - - - - - - - - - - - - - X-Ray Photon - Photon pumps electron to higher energy state
  23. 23. Add module code number and lesson title 36 (Images courtesy of AFGA) PSP digitizer Casette and PSP Workstation
  24. 24. Reading Imaging Plate Reader scans plate with laser Laser releases electrons trapped in high energy states Electrons fall to low energy states Electrons give up energy as visible light Laser Beam Higher Energy Elect ron St at e Lower Energy Elect ron St at e - - - - - - - - - - - - - - - - - - - - - - - - - - - - Lower Energy Electron State
  25. 25. Reader scans plate with laser light using rotating mirror Film pulled through scanner by rollers Light given off by plate measured by PM tube & recorded by computer Reading Imaging Plate
  26. 26. Conventional CR Scanning
  27. 27. 25% OF STORED ENERGY WITHIN 8 HOURS
  28. 28. CR PLATE CR SCANNER/READER CR AFTER EXPOSURE IS INSERTED INTO CR SCANNER
  29. 29. CR Exposure & Readout
  30. 30. PM TUBE AMPLIFIER ADC LASER LIGHT GATE
  31. 31. PLATE & F-CENTERS LASER 633 nm PHOTOSTIMULABLE LUMINESCENCE 390-400 nm
  32. 32. After read-out, plate erased using a bright light Plate can be erased virtually without limit Plate life defined not by erasure cycles but by physical wear
  33. 33. IMAGE DISPLAY Typical image plate can be reused thousands of times
  34. 34. CR Resolution Small cassettes have better spatial resolution Smaller pixels More pixels / mm
  35. 35. IMAGE CHECK-INDEX
  36. 36. IMAGE MANIPULATION-WINDOWING
  37. 37. PICTURE DESTINATION -PACS
  38. 38. CR CHARACTERISTIC CURVE VERY WIDE LATITUDE CR SYSTEMS LESS RADIOGRAPH REPEATS
  39. 39. Much greater latitude than screen/film Plate responds to many decades of input exposure under / overexposures unlikely Computer scale inputs exposure to viewable densities Unlike film, receptor separate from viewer
  40. 40. CHARACTERISTIC CURVE LATITTUDE OF CR LATITTUDE OF FILM
  41. 41. IMAGE CAN BE SALVAGED WITH CR 500% OVEREXPOSURE 80% UNDEREXPOSURE USE ADEQUATE KVP
  42. 42. HARD COPY GENERATED IN LASER PRINTER
  43. 43. CR SYSTEM EFFICIENCY CHARACTERISTIC QDE- QUANTUM DETECTION EFFICIENCY NO NEED FOR SCREENS QDE: THE MEASURE OF THE EFFICIENCY OF CR SYSTEM TO CONVERT REMNANT X-RAYS TO USEFUL IMAGE SIGNAL QDE PATIENT DOSE
  44. 44. Receptor provides direct digital output No processor / reader required Images available in < 15 seconds Much less work for technologist
  45. 45. 69
  46. 46. 72
  47. 47. PACS and DICOM  THE ROLE OF PACS : A Picture Archiving and Communication System (PACS) aims to replace conventional analogue film and paper clinical request forms and reports with a completely computerized electronic network whereby digital images are viewed on monitors in conjunction with the clinical details of the patient and the associated radiological report displayed in electronic format.  The ROLE OF DICOM: Digital Imaging and Communications in Medicine (DICOM) is a standard for handling, storing, printing, and transmitting information in medical imaging. It includes a file format definition and a network communications protocol. DICOM enables the integration of scanners, servers, workstations, printers, and network hardware from multiple manufacturers into a picture archiving and communication system (PACS). The different devices come with DICOM conformance statements which clearly state the DICOM classes they support. DICOM has been widely adopted by hospitals .
  48. 48. ?

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