Oct.2013 c.r


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    Accounts for 85% of the total number of repeat exposures.
    Has a direct affect on exposure technique.
  • Oct.2013 c.r

    1. 1. Digital Radiography Understanding Digital Radiography Principles Dr. Hussein Ahmed Hassan Original Inverted Embossed
    2. 2. Purpose: Basic Answers What is digital radiography? What components are required? What types of digital radiography work best in practice?  How do we choose the right solution for our program?  What are the computer and networking requirements to support our digital solution?   
    3. 3. What is Digital Radiography?  Sensors or phosphor plates take the place of traditional film.  Radiographic images are acquired almost instantly and stored electronically.  They can be manipulated, viewed, and transferred with a software program.
    4. 4. What Components are required for Digital Radiography?  Sensors or phosphor plates to replace x-ray film.  Imaging software that allows image storage and management.  Computer system to run imaging software.  Optional: Practice management software –for completely paperless patient records management.
    5. 5. Digital Radiography  Is a form of x-ray imaging, where digital X-ray sensors are used instead of traditional photographic film.  Advantages include; 1. Time efficiency through bypassing chemical processing 2.The ability to digitally transfer and enhance images. 3.Less radiation can be used to produce an image of similar contrast to conventional
    6. 6. Digital Imaging Technology Digital methods for processing and displaying x-ray images were first introduced with the advent of computed tomography (CT) in 1972. Continuing advances in computer technology have promoted the general development of image acquisition in digital form (CCD cameras), most commonly from image intensifiers (digital fluoroscopy) or from storage phosphor plates (computed radiography). Other detector systems such as ‘flat-panel’ technology for indirect or direct digital radiography are now available for general purpose equipment.
    7. 7. Capture technologies used today: • Screen/film (S/F) combination system • Image intensifiers • Computed radiography (CR) with storage phosphors • Direct Digital radiography (DDR)
    8. 8. Image Acquisition Conventional X-ray Drying X-ray fixer water developer water
    9. 9. Image Acquisition in Digital Imaging  There are a number of technologies used for digital imaging in planar radiography these are; 1. Computed radiography (CR), CR in first appearance, similar to the used of film/screen system. The CR plate is in a cassette, which will fit the table and vertical Backy trays and can be used with mobile equipment. The plate is then scanned in a reading system, this make the change to computed radiography (CR) easier.
    10. 10. Image Acquisition CR X-ray Tube Latent image Photomultiplier Readout Erasure ADC IP Ready Fluorescent Lamp Workstation
    11. 11. 2.Direct Digital  Means, instead of using x-ray film, a sensor connects directly to your computer - the x-ray image displays almost immediately after taking it.  Sensors use either a Charge Coupled Device (CCD), or a Complementary Metal Oxide Semiconductor (CMOS) or thin-film transistor (TFT) to convert light into electrons. These are collected & turned into pixels that show brightness and contrast - that’s what makes a digital x-ray image.  You still use your regular x-ray machine to take the exposure.  Both CCD sensors, CMOS sensors and TFTwork extremely well.
    12. 12. Direct Digital Radiography --cot---Direct Digital Radiography (DDR), DDR system needs more changes in x-ray couch and vertical backy design and often changes to x-ray tube assembly, DR detector is fully integrated into exposure equipment. The patient is radiographed and the image appears on workstation in few seconds. Here image optimized and then sent for reporting or repeated if necessary.
    13. 13. Image Acquisition DR 1.X-ray scintillator bonded to readout ray, thin-film transistor (TFT) X-ray Tube Workstation Detectors (TFT)
    14. 14. Why do we need a new technology, what is wrong with film/screen? • Absolutely nothing !!!! • Still the “gold standard” to which all new projection radiography systems are measured against • On many accounts (e.g.: mammography) , S/F is still superior than some new technologies (e.g.: CR) • The choice of technology depends on clinical, technical, operational and economic factors
    15. 15. Uses Digital Radiography  CR is used in all areas where film/screen systems are currently used, including mammography.  Direct Digital Radiography (DDR) can be used in general radiography and mobile radiography.  DDR is very popular in small-field mammography and being introduced into full-field mammography.  DDR detectors are now being used instead of image intensifiers in fluoroscopy.
    16. 16. Computed Radiography What is it?  Computed Radiography, commonly known as CR, is a digital radiography process that is designed to replace industrial radiographic film  The CR process is very similar to the process associated with film … mainly because of the film-like digital detector that is used to capture the radiographic image  The CR film-like digital detector is a flexible phosphor screen that looks and feels a lot like film
    17. 17. CR Cassettes Storage phosphor (SP) screens are similar in structure to conventional intensifying screens
    18. 18. Computed Radiography Storage Phosphor Digital X-ray Imaging Systems
    19. 19. Computed Radiography How does it work? Step 1: The phosphor screen is inserted into a soft or hard cassette (with or without lead) Step 2: A radiation pattern is exposed on the phosphor screen creating a latent image Step 3: The phosphor screen is then inserted into a phosphor scanner to be read Step 4: The phosphor screen is scanned and the digital image is displayed on the workstation monitor for review and evaluation Step 5: The phosphor screen is then erased and ready to be reused
    20. 20. Computed Radiography System Process Differences between Phosphor & Film Step 1: The phosphor screen is inserted into a soft or hard cassette (with or without lead screens) Do not need a light-tight darkroom for phosphor imaging Step 2: A radiation pattern is exposed on the phosphor screen creating a latent image Phosphor is faster and much more forgiving (wide latitude) Step 3: The phosphor screen is then inserted into a phosphor scanner to be read No chemical. Film processor (8 minutes) vs. Phosphor (1 to 2 minutes) Step 4: The phosphor screen is scanned and the digital image is displayed on the workstation monitor for review Digital image can be enhanced increasing OD Step 5: The phosphor screen is then erased and ready to be reused The phosphor screens are reusable
    21. 21. Computed Radiography System Process Similarities between Phosphor & Film Step 1: The phosphor screen is inserted into a soft or hard cassette (with or without lead screens) Just like film Step 2: A radiation pattern is exposed on the phosphor screen creating a latent image Shot set-up and technique are basically the same Step 3: The phosphor screen is then inserted into a phosphor scanner to be read Very similar to film being put into a film processor Step 4: The phosphor screen is scanned and the digital image is displayed on the workstation monitor for review Film is put on a lightbox to view Step 5: The phosphor screen is then erased and ready to be reused
    22. 22. Computed Radiography System Components Overview
    23. 23. Computed Radiography System consists of the following components: WORKSTATION & SOFTWARE PHOSPHOR SCANNER & ERASER PHOSPHOR SCREENS
    24. 24. Computed Radiography System Workstation and Software
    25. 25. Computed Radiography System Workstation and Software  Operates the Phosphor Scanner  Manages your images and associated data: drawings, word documents, digital photos, procedures, reference images, techniques, etc.  Image enhancement capabilities: zoom, gray-scale manipulation, pan & scroll, density & measurements tools (histograms, point profiles, line profiles, line and area measurements), image processing, annotation, etc.  Ability to save and archive your digital images and associated data
    26. 26. Computed Radiography System Phosphor Scanners Two different types of Phosphor Scanners
    27. 27. Computed Radiography Systems Table-top CR100 CR Tower
    28. 28. Computed Radiography System (Table-top Unit) consists of the following components: WORKSTATION & SOFTWARE PHOSPHOR SCANNER Phosphor Screen is placed directly into the scanner PHOSPHOR SCREENS
    29. 29. Computed Radiography System (CR Tower Free-Standing Unit) consists of the following components: WORKSTATION & SOFTWARE PHOSPHOR SCANNER Hard-cassette based system PHOSPHOR SCREENS
    30. 30. Phosphor Scanners How is the phosphor screen scanned? He-Ne laser rotating mirror light-guide PMT storage phosphor plate
    31. 31. Overall mechanism
    32. 32. Computed Radiography System Phosphor Imaging Screens and customized Cassettes
    33. 33. Computed Radiography Phosphor Screens Manufactured in similar sizes as film Utilizes the same cassettes as film Utilizes the same x-ray sources as film Set-up in the field is the same as film Typically faster exposures than film Very wide latitude which makes it much more forgiving than film / less reshots  No chemicals required for processing  Image quality good match for aircraft applications      
    34. 34. PSP- PhotoStimulated Phosphor  Reusable plastic plate  Laser scanning - the coated with phosphor trapped electrons are released  It stores the energy of photostimulated the remnant x-ray - xluminescence ray photons excites the  The emitted light is electrons in the phosphor. detected by photomultiplier tube, and is digitized to form an image
    35. 35. Computed Radiography How is the phosphor screen manufactured (very similar to film)? phosphor layer phosphor grains protective layer substrate
    36. 36. Computed Radiography Technology The active phosphor layer of a CR plate usually comprises a layer of europium-doped barium fluorobromide, which is coated on to a semi-rigid or flexible polyester base. phosphor layer phosphor grains protective layer substrate X-ray photons are absorbed by the phosphor layer, the phosphor electron become excited and raised to high energy level, where they can stay trapped in semi-stable high energy state. The trapped electron represent a latent image in the phosphor plate in form of stored energy. The stored energy is released by adding energy to the trapped electron This done by stimulation with laser beam, the trap electrons then escap from the traps to fall back to their equilibrium state.
    37. 37. Computed Radiography Technology---cot---- As the electrons fall back, the electrons release energy in form of light. This phenomenon is known as photostimulable luminescence (PSL). The emitted light intensity is proportional to original x-ray intensity. The light energy detected and signal is digitized and processed digitally to produce a visible diagnostic radiograph  on a monitor. The phosphor plate is then erased with a bright white light t remove any remaining trapped electrons, and the plate is then ready for the next examination.
    38. 38. Directed Digital Radiography (DDR) Directed digital radiography, a term used to describe total electronic imaging capturing. Eliminates the need for an image plate altogether.
    39. 39. Amorphous Selenium detector technology for DR Direct Radiography
    41. 41. Densities of the IMAGE  The light is proportional to amount of light received  digital values are then equivalent (not exactly the same) to a value of optical density (OD) from a film, at that location of the image
    42. 42. CR VS DR – CR -Indirect capture where the image is first captured on plate and stored = then converted to digital signal – DDR -Direct capture where the image is acquired immediately as a matrix of pixels – sent to a monitor
    43. 43. DIRECT RADIOGRAPHY      uses a transistor receiver (like bucky) that captures and converts x-ray energy directly into digital signal seen immediately on monitor then sent to PACS/ printer/ other workstations FOR VIEWING
    44. 44. CR vs DR CR  imaging plate  processed in a Digital Reader DR  transistor receiver (like bucky)  directly into digital signal  Signal sent to computer  Viewed on a monitor  seen immediately on monitor –
    45. 45. ADVANTAGE OF CR/DR  Can optimize image quality  by manipulating digital data  to improve visualization of anatomy and pathology  AFTER EXPOSURE TO PATIENT
    47. 47. ADVANTAGE OF CR/DR vs FS Rapid storage retrieval of images NO LOST FILMS! PAC (storage management) Teleradiology - long distance transmission of image information  Economic advantage - at least in the long run?    
    48. 48. CR/DR VS FILM/SCREEN  FILM these can not be modified once processed  If copied – lose quality  DR/CR – print from file – no loss of quality
    49. 49. “no fault” TECHNIQUES F/S: RT must choose technical factors (mAs & kvp) to optimally visualize anatomic detail CR: the selection of processing algorithms and anatomical regions controls how the acquired latent image is presented for display  HOW THE IMAGE LOOKS CAN BE ALTERED BY THE COMPUTER – EVEN WHEN “BAD” TECHNIQUES ARE SET
    50. 50. DR Initial expense high very low dose to pt – image quality of 100s using a 400s technique  Therfore ¼ the dose needed to make the image   
    51. 51. Storage /Archiving FILM/SCREEN  films: bulky  deteriorates over time  requires large storage & expense  environmental concerns  CR & DR  8000 images stored on CD-R  Jukebox CD storage  no deterioration of images  easy access
    52. 52. Computed Radiography System Compatibility & Growth Opportunities Most of the CR Workstations also have the ability to operate a wide variety of: - printers - document scanners - archiving hardware - film digitizers - flat panel arrays - and other digital detectors
    53. 53. Transmission of Images  PACS - Picture Archiving & Communications System  DICOM - Digital Images & Communication in Medicine  TELERADIOGRAPHY -Remote Transmission of Images
    54. 54. Digital imaging technology (cont) The technique of digital subtraction angiography (DSA), based on digital image processing, allows enhanced visualization of blood vessels by electronically subtracting unwanted parts of the image.
    55. 55. Digital subtraction angiography. (a) Mask ,immediately prior to contrast injection a preliminary digitized image known as the “mask” is performed. Note pelvic bone, bowel gas and arterial catheter. (b) Contrast image. Contrast is injected through the catheter producing opacification of arteries. (c) Subtracted image. The computer subtract the mask from the contrast image leaving an image of contrast fill blood vessels unobscured by overlying bone and bowel. Note a tight localized stenosis of the right common illiac artery (arrow)
    56. 56. Digital imaging technology At this time, there is no consensus on the best technology for balancing dose and image quality. Digital imaging potentially can provide lower doses than the film-intensifying screen method. However, through post-exposure manipulation of the data, satisfactory diagnostic images can be produced even when unnecessarily high patient radiation doses are used. Proper quality assurance procedures are essential.
    57. 57. Main Characteristics of an Image Receptor The selection of an imaging system should involve a thorough evaluation and analysis of its complete characteristics together with consideration of the technical and human environment in which the system will be used. The main characteristics to be considered when selecting an image receptor are:spatial resolution; contrast resolution; dose efficiency; Modulation Transfer Function; detector size; possibilities of image storage and transfer; and qualities such as weight, robustness, fast image access, etc).
    58. 58. CR - ? Which shows “better detail” Why/how? 8 x 10 cassette 14 x 17 cassette
    59. 59. To Produce Quality Images For Conventional Projection or CR Radiography: The same rules, theories, and laws still apply and can not be overlooked FFD/OFD (SID/SOD) Inverse Square Law Beam Alignment Tube-Part-Film Alignment Collimation Grids Exposure Factors: KVP, MaS Patient Positioning
    60. 60. 90 KVP GE DR
    61. 61. BURNING
    62. 62. 0˚ Angle 30˚ Angle 50˚ Angle
    63. 63.  towel that was used to help in positioning a child  CR is MORE sensitive to  ARTIFACTS NEW IMAGE
    64. 64. CR image – NEW IMAGE  Line caused from dirt collected in a CR Reader
    65. 65. Double exposure Child
    66. 66. 120 KVP Fuji CR
    67. 67. ? Hands over upper abdomen
    68. 68. High resolution with digital imaging
    69. 69. Vertical patterns of hyperintense signal  usually represent foreign materials that are stuck to the light path assembly that acquires the photostimulated luminescence signal from the CR imaging plate as it is being scanned by a laser beam. As the light is blocked at the same spot as the plate translated through the optical stage, the artifact occurs perpendicular to the laser beam readout, in the plate translation (slow-scan) direction. The stripe appears bright, since the image undergoes a reverse grayscale transformation to make the image appear similar to a screen-film image with processing.
    70. 70. A lateral chest image with an unusual superimposed pattern on the anatomy.  This is an example of a CR image obtained with cassette reversed, where the tube side of cassette is pointed away from the x-ray tube source and toward the patient. Cassette plastic structural patterns are projected onto the imaging plate (particularly noticeable in the arms and anterior part of the patient.
    71. 71. ‫المأذن حرابنا والقباب خوزاتنا مساجدنا ثكناتنا والمصلون جنودنا وهذا الجيش المقدس يحمي ديننا‬ ‫محمد عاكف شاعر تركى‬
    72. 72. THANK YOU!! Question?