Quality Management ch 9

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  1. Where does the word pixel come from?
    It's a contraction of the term 'picture element'.
  2. What is the relationship between image matrix (pixels) and spatial resolution?
    The more pixels in a matrix, the smaller each pixel becomes, thereby increasing spatial resolution.
  3. Name 5 advantages that digital imaging has over analog (film/screen) imaging:
    • 1 Reduced repeats due to technique errors.
    • 2 Simplified filing system.
    • 3 Reduced number of lost images.
    • 4 Improved post-processing.
    • 5 Electronic transmission of images.
  4. Name 3 methods of acquiring digital images:
    • 1 Secondary capture.
    • 2 Computed Radiography (CR)
    • 3 Digital Radiography (DR)
  5. What is secondary capture?
    Converting an analog image (film) into a digital format.
  6. Name two ways that secondary capture can be accomplished. Of these two, which one is the appropriate way if a diagnosis is being sought from the image?
    • 1 Taking a picture of film with a digital camera.
    • 2 Using a laser scanning digitizer. (Diagnostic)
  7. Name 4 common uses for secondary capture:
    • 1 Film radiographs are archived on Picture Archiving and Communication Systems (PACS)
    • 2 Computer-aided diagnosis is a software program used to look for abnormalities in mammo and CXR.
    • 3 Teleradiology allows sending digitized images to distant locations for interpretations and consultations.
    • 4 Duplicate images allow originals to stay on site and CDs to be given to patients.
  8. When was CR developed? What year was it first used clinically?
    • Developed in 1981 (fuji corp)
    • First used in 1983
  9. True/False: CR uses a standard xray tube, standard generators, an image reader device and a workstation.
  10. What makes up the outside and inside of the image cassette in CR?
    • Outside - carbon fiber with barcode
    • Inside - plate made of metal or plastic with one side coated with photostimulate phosphors.
  11. What is PSL?
    • Photostimulated Luminescence
    • This is when the crystals are energized by xrays until exposed to a laser.
  12. What is an F-center? And what occurs in the F-center?
    This is where the crystals are trapped in empty lattices, when laser light hits the F-center, trapped electrons are released causing the emission of visible light (blue light) which is detected by photosensors.
  13. Briefly describe how CR works:
    When image receptor is exposed to xrays, electrons are trapped.  The processor exposes a laser to receptor which releases electrons emitting light. Photosensors collect light data creating a digital signal and image.
  14. Describe all 12 functions of the workstation:
    • 1 Gradational contrast enhancement.
    • 2 Spatial frequency enhancement (recorded detail).
    • 3 Histogram equalization - eliminated non-useful black and white pixels.
    • 4 Look-up tables - portray desired brightness.
    • 5 Subtraction/addition option - removes anatomy or scatter to increase contrast.
    • 6 Image magnification - electronic.
    • 7 Region of interest display.
    • 8 Statistical analysis.
    • 9 Windowing - width and level (contrast and brightness).
    • 10 Energy subtraction - photon energies determine subtracting bone or soft tissues.
    • 11 Image stitching.
    • 12 Database functions - for hard copy printing.
  15. Describe the 7 advantages of CR versus conventional (film/screen) radiography:
    • 1 lower patient dose
    • 2 lower repeat rate
    • 3 Higher contrast resolution and wider exposure latitude
    • 4 No dark room or film costs
    • 5 Post-processing can improve quality
    • 6 Image storage
    • 7 Easy interface - Picture Archiving and Communication Systems (PACS)
  16. Describe the 5 disadvantages of CR versus conventional radiography:
    • 1 Higher capital costs
    • 2 Lower spatial resolution
    • 3 Image quality dependent on collimation and centering
    • 4 Potential for over exposure and high dose to patient
    • 5 Image artifacts
  17. When did digital radiographs first appear clinically?
    Late 1990's
  18. What are 2 other names that digital radiography is known as?
    • Flat plate
    • Flat panel
  19. True/False: The active matrix array is similar to a CCD cameral used in digital cameras, digital camcorders, and television cameras in fluoroscopic systems.
  20. Briefly describe how DR works:
    Image receptor sends an electronic signal directly to digital image processor.
  21. What are the 2 types of flat-panel devices that have been developed?
    • indirect-conversion image receptor
    • direct-conversion image receptor
  22. What is indirect-conversion?
    • Converting xray energy into light energy, then light into an electronic signal.
    • Phosphor material
  23. What is direct-conversion?
    • Converts xray energy directly into an electronic signal.
    • Photoconducting material (Amorphous selenium)
  24. Compare and contrast CR and DR:
    • CR - is more portable, lower cost, and easier to install.
    • DR - has higher transfer effeciency, less labor intensive, and reduce exam time.
  25. Due to the variety of digital systems available for institutional purchase there is no standard set of QC procedures that are common for all systems. However, there are some basic QC procedures that can be employed. List these and give a brief description:
    • 1 Check CR system - loading and unloading mechanisms. Cleaned and lubricated. CR cassettes cleaned/inspected/erased.
    • 2 Laser scanning digitizers - cleaned.
    • 3 DR image receptors - cleaned.
    • 4 Monthly check of display monitors.
    • 5 A resolution test tool should be used every 6 months. A) uniformity- expose film, process and look for uniformity. B) Spatial accuracy - wire mesh tool. C) Erasure test - take image, erase, process erased image. D) Laser function - expose a straight ruler, process, varify straight lines.
  26. List and describe the 3 levels of system performance for quality control and system maintenance:
    • 1 Routine - performed by techs.
    • 2 Full inspection - performed by medical physicists.
    • 3 System adjustments - performed by vendor personnel.
  27. What is an acceptance test and who performs these?
    Performed by medical physicists on brand new equipment to ensure it performs at the manufacture's specifications.
  28. What does a daily test consist of and who performs this?
    • Performed by techs
    • 1 Inspect cassettes - cleanliness.
    • 2 Check laser printer functioning properly for hard copies.
    • 3 Erase all IPs (imaging plates) before use.
    • 4 Verify reader unit and workstations are communicating.
    • 5 Perform processor QC if laser camera is used for hard copies.
  29. What does a weekly test consist of and who performs this?
    • Performed by techs
    • 1 Verify monitor calibration.
    • 2 Test phantom images.
    • 3 Clean and inspect all image receptors.
    • 4 Clean air intake ports.
    • 5 Clean computer keyboard and mouse.
    • 6 Clean monitor screens.
  30. What does a monthly test consist of and who performs this?
    • Performed by techs
    • 1 Film processor maintanence.
    • 2 Inspect and clean all image receptors.
    • 3 Perform repeat analysis.
    • 4 Review service logs.
  31. What does a semiannual/annual test consist of and who performs this?
    • Performed by medical physicists
    • 1 Xray generator tests - generator, tube, and accessories.
    • 2 Evaluate image quality.
    • 3 Evaluate image processing.
    • 4 Repeat acceptance test.
    • 5 Review patient exposure trends.
    • 6 Evaluate exposure indicator (EI) accuracy.
    • 7 Determine necessary system adjustments.
  32. Describe the concept of digital fluoro:
    • Computerized fluoro.
    • Digitizing electronic signal and sending into a computer for real-time processing.
  33. Define last frame-hold:
    Allows the last image in the computer memory to be displayed in the monitor even when beam is off.
  34. Define road-mapping:
    Allows image to be captured and displayed on a monitor while second monitor shows real-time images.
  35. Define digital temporal filtering:
    Adds together different image pixel values and averages the values during display of successive images.
  36. Define image enhancement:
    • Window width - contrast
    • Window level - brightness
  37. Define image restoration:
    Corrects distortion and vignetting.
  38. What is the main application for digital fluoro systems?
    The main application for digital fluoro systems is for digital subtraction angiography (DSA).
  39. Describe digital subtration angiography:
    • Involves removing or subtracting background structures from an image so that only contrast media-filled structures remain.
    • Two images are taken: 1 with contrast then 1 without contrast. This is how it knows what to subtract.
  40. Name 3 groups or organizations that have published guidelines for QC procedures:
    • 1 (NEMA) National Electronic Manufacterer's Association
    • 2 (SMPTE) Society of Motion Picture and Television Engineers
    • 3 (DICOM) Digital Imaging and Communications in Medicine
  41. What parameters should be evaluated during daily QC of the electronic display devices?
    • 1 Turn on computer and allow 30 min to boot-up and warm-up.
    • 2 Cleanliness of front screen.
    • 3 Geometric distortion.
    • 4 General image quality and appearance.
    • 5 Luminance - varify all 16 luminance patches are visible.
    • 6 Resolution - varify all letters and numbers are visible.
  42. What are the 4 main components of a PACS system? Define/Describe each one:
    • 1 Image acquisition - downloading image from CR, DR, MR, CT, etc.
    • 2 Image storage and retrieval - controlled by PACS server.
    • 3 Image display and interpretation - viewing stations.
    • 4 The communications network - transmission of images.
  43. Which of the following is found inside the image receptor used for a CR system?
    a. Intensifying screen
    b. Duplitized film
    c. Imaging plate
    d. All of the above
    d. All of the above
  44. Which of the following is an advantage of CR versus conventional radiography?
    a. Lower patient dose
    b. Higher contrast resolution
    c. Edge enhancement
    d. All of the above
    d. All of the above
  45. Which of the following is true in comparing CR versus conventional radiography?
    A. CR has greater spatial resolution
    B. CR demonstrates larger image size that conventional imaging
    C. CR has lower capital costs
    D. Collimation and part centering are critical for CR imaging
    D. Collimation and part centering are critical for CR imaging
    (this multiple choice question has been scrambled)
  46. The laser used in most CR reader units emit light in this portion of the color spectrum:
    A. Green
    B. Blue-violet
    C. Red
    d. All of the above
    C. Red
    (this multiple choice question has been scrambled)
  47. Which of the following are components of a CR system: (1) image receptors. (2) reader unit, or (3) workstation:
    A. 1 and 2
    B. 2 and 3
    C. 1 and 3
    D. 1, 2 and 3
    D. 1, 2 and 3
    (this multiple choice question has been scrambled)
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Quality Management ch 9
2014-12-14 22:07:10
Quality Management

Quality Management ch 9
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