Cr & dr

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  • 1. Dr. Muhammad bin zulfiqar PGR-1 SIMS/ SHL.
  • 2. Basics of Digital Language
  • 3. Byte The basic unit of binary coded information Kilobyte—210 – 1024 bites Megabyte—1024 times1024bites 5
  • 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. Performance Parameters(contd..) 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.
  • 6. DIGITAL PROJECTION RADIOGRAPHY COMPUTED RADIOGRAPHY (CR) DIGITAL RADIOGRAPHY (DR)
  • 7. X-RAYS CR CR PLATE SCANNER 11011101
  • 8. X-RAYS DR DETECTORS 11011101
  • 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. Computed Radiography (CR) Re-usable metal imaging plates replace film & cassette Uses conventional bucky & x-ray equipment                                                                   
  • 11. CR SYSTEM COMPONENTS CASSETTES (phosphor plates) ID STATION IMAGE PREVIEW STATION DIGITIZER VIEWING STATION
  • 12. CR PLATE
  • 13. CASETTE CONSTRUCTION LIGHTWEIGHT ALUMINUM PLASTIC STEEL FRAME FRONT PANEL MADE OF LOW ATTENUATION CARBON FIBER
  • 14. PROTECTIVE LAYER PHOSPHOR LAYER ANTI-HALO & REFLECTIVE LAYER BASE BACKING LAYER
  • 15. PHOSPHOR LAYER Ba FX: Eu +2 BASE PET- POLYETHYLENE TERAPHTALATE PROTECTIVE LAYER FLUORINATED POLYMER MATERIAL PROTECTS PHOSPHOR LAYER
  • 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. SCATTER
  • 18. REMOTE OPERATOR PANEL
  • 19. CR Operation
  • 20. Add module code number and lesson title 29
  • 21. The principle of PSP PMT ADC CB Trap Excitation Storage Add module code number and lesson title Emission 30
  • 22. - X-Ray Photon Higher E nergy Electron State P hoton pumps electron to higher energy state - - - Lower E nergy - - Electron - State - - - -
  • 23. PSP digitizer (Images courtesy of AFGA) Add module code number and lesson title Casette and PSP Workstation 36
  • 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 Electron State Lower Energy Elect ron St at e - - - - - - - - - - - - - - - -
  • 25. Reading Imaging Plate 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
  • 26. Conventional CR Scanning
  • 27. 25% OF STORED ENERGY WITHIN 8 HOURS
  • 28. CR PLATE CR SCANNER/READER CR AFTER EXPOSURE IS INSERTED INTO CR SCANNER
  • 29. CR Exposure & Readout
  • 30. LASER PM TUBE LIGHT GATE AMPLIFIER ADC
  • 31. LASER 633 nm PHOTOSTIMULABLE LUMINESCENCE 390-400 nm PLATE & F-CENTERS
  • 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. IMAGE DISPLAY Typical image plate can be reused thousands of times
  • 34. CR Resolution Small cassettes have better spatial resolution Smaller pixels More pixels / mm
  • 35. IMAGE CHECK-INDEX
  • 36. IMAGE MANIPULATION-WINDOWING
  • 37. PICTURE DESTINATION -PACS
  • 38. CR CHARACTERISTIC CURVE VERY WIDE LATITUDE CR SYSTEMS LESS RADIOGRAPH REPEATS
  • 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. CHARACTERISTIC CURVE LATITTUDE OF FILM LATITTUDE OF CR
  • 41. IMAGE CAN BE SALVAGED WITH CR 500% OVEREXPOSURE 80% UNDEREXPOSURE USE ADEQUATE KVP
  • 42. HARD COPY GENERATED IN LASER PRINTER
  • 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. Receptor provides direct digital output No processor / reader required Images available in < 15 seconds Much less work for technologist
  • 45. 69
  • 46. 72
  • 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. ?