Final Quality

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Final Quality
2011-07-27 20:28:51

quality final
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  1. What is the purpose of quality control testing?
    minimizes the risk of suboptimal images but can not prevent them entirely
  2. Steps involved in outcomes assessment include?
    repeat analysis, artifact analysis, analysis of accuracy, analysis of sensitivity, and analysis of specificity.
  3. What are the benefits of repeat analysis?
    When repeats are kept to a minimum, departmental efficiency increases. Patient exam time is reduced and patient satisfaction is increased.

    -Repeat analysis provides important data about equipment, departmental procedures, and the skill of the technologists.
  4. How do you calculate total repeat rate?
    The total repeat rate is found by dividing the total number or repeated films by the total number of films used for the time period in question.
  5. How does you calculate causal repeat rate? and what is its acceptance limits?
    •The causal repeat rate is the percentage of repeats from a specific cause. This is found by dividing the number of repeats from a specific cause by the total number of repeated films.

    Departmental repeats rates should not exceed 4% to 6%.
  6. Emulsion Pickoff?
    Emulsion pickoff occurs when emulsion is removed from the film base. This occurs when films are stuck together during processing and then pulled apart afterward.
  7. Gelatin buildup occurs?
    when emulsion that has been removed from previous films builds up on the rollers or becomes dissolved in the developer. It is then deposited on films. The primary cause for this is under replenishment of the developer or failure of the developer circulation system filter.
  8. Curtain effect is caused by?
    solution dripping on or running down a film. This can occur if the wash water is dirty or a film has jammed and must be removed from the processor before going through the dryer.
  9. Chemical fog?
    is an overdevelopment of the film that results in excessive base plus fog and Dmin on sensitometry films and excessive radiographic density on patient exams. Causes include increased developer temperature, time in developer, pH, or concentration of developer. It may also occur with over replenishment of developer solution.
  10. Guide shoe marks?
    are scratches on films made by bent, worn, damaged, or misaligned guideshoes. Guideshoe marks run parallel to the direction of film travel.
  11. Pi lines?
    are artifacts that occur in relation to the circumference of a roller. They occur at regular intervals and run perpendicular to the direction of film travel.
  12. Chattering artifacts?
    appear as bands of increased density that occur perpendicular to film direction. Chatter is caused by inconsistent motion of the transport system, usually because the drive gears or drive chain slips
  13. Dichotic stain?
    presence of stains that are either brown or greenish yellow. Brown stains on a film either indicate that the film was processed in oxidized developer or if the stain develops after years of storage, hyporetention may be the cause. A greenish yellow stain indicates the presence of silver halide crystals remaining in the film from incomplete fixation.
  14. Reticulation marks?
    appear as fine grooves in the surface of the film. This is the result of excessive expansion and contraction of the film during processing due to uneven solution temperatures.
  15. Streaking?
    can be caused by uneven development of the image due to failure of the circulation system.
  16. Hesitation marks (stub lines)?
    are stripes of decreased density from transport rollers being left in contact with the film, preventing development. These artifacts occur if power is lost while the film is in the developer solution, if the speed of the transport system is dramatically decreased, or if the film becomes stuck while in the developer.
  17. Water spots?
    appear as an increase in optical density due to liquid coming in contact with an unprocessed film.
  18. Wet pressure sensitization (entrance roller marks)?
    appear as a series of dark stripes that match the grooves of the entrance rollers. This occurs if the rollers become wet. The combination of pressure and water marks the film. This may also occur if the tension of the entrance rollers is too great.
  19. Hyporetention?
    is a white, powdery residue that remains on the surface of films because of incomplete washing. Hyporetention can also result in brown dichotic stains with aging.
  20. Excessive optical
    can be caused by excessive developer time, too high of a developer temperature, over replenishment, high pH, or excessive developer concentration
  21. Insufficient optical density?
    can be caused by developer temperature that is too low, not enough time spent in the developer, under replenishment, contamination of the developer with fixer, pH that is too low, or insufficient developer concentration.
  22. Exposure artifacts?
    are caused by the patient, tech, or the equipment during an exam.
  23. Motion causes?
    a blurring of the image, resulting in a loss of recorded detail
  24. Sparks from static electricity?
    expose the film and produce tree, crown, or smudge static.
  25. Crescent or crinkle marks?
    are half moon shaped marks of increased density caused by bending the film before processing
  26. What cause improper image brighntess?
    Improper image brightness can occur in CR if an incorrect histogram is selected or improper collimation is used.
  27. What is heat blur?
    Heat blur is a blurring of the image that can occur when a CR cassette is exposed to intense heat before being processed by the CR reader.
  28. What is accuracy? what is sensitivity? what is specificity?
    Accuracy is a measure of the percentage of cases that are diagnosed correctly.

    Sensitivity is a measure of the likelihood of obtaining a positive diagnosis in a patient who is actually positive for a disease. It is a measure of the true positives divided by the number of people actually positive for the disease (true positives plus false negatives).

    Specificity is a measure of the likelihood of a patient obtaining a negative diagnosis when there is actually no disease present. It is a measure of the true negatives divided by the number or people actually negative for disease (true negatives plus false positives).
  29. T/F: every vendor is required to suply their own phantom?

    Each vendor is required to supply phantoms capable of testing contrast scale, noise, slice thickness, spatial resolution for both high and low contrast objects, and a mean CT number for water.
  30. The Medicare Improvements for Patients and Providers Act of 2008?
    • mandates that any nonhospital institution performing advanced diagnostic services such as CT must be accredited by January 2010 in order to
    • receive Medicare reimbursement. (already passed)
  31. The CARE bill?
    if passed would provide similar requirements for hospitals as well.
  32. In order to maintain ACR accreditation, the QC program must be implemented and overseen by a qualified medical physicist. The physicist will conduct an annual performance evaluation of the equipment and determine the frequency for performance of each test by a qualified CT technologist. ACR recommendation for testing includes alignment light accuracy, slice14thickness, image quality, high contrast resolution, low contrast resolution, image uniformity, noise, artifact evaluation, CT number accuracy, and display devices. Testing can be done with either the ACR phantom or vendor supplied phantom.
  33. T/F: high contrast resolution is a QC test in CT?
  34. High Contrast resolution QC test?
    High contrast spatial resolution is described as the minimum distance between two objects that allows them to be seen as separate and distinct. The physicist may measure this is terms of point spread function and modulation transfer function. The technologist measures this by imaging a test object with a bar or hole pattern.
  35. Low contrast resolution CT test?
    Low contrast resolution is the ability of a CT system to demonstrate subtle differences in tissue densities.

    Low contrast resolution is expressed as either the smallest diameter of an object with a specific contrast that can be detected or the smallest difference in attenuation that can be identified for an object of a specific diameter.

    A phantom consisting of rows of holes of varying sizes filled with a liquid that has a CT number different from the surrounding plastic is image
  36. What is noise?
    Noise represents the portion of the CT image that contains no useful information.

    It is defined as the random variation of CT numbers about a mean value when an image of a uniform object is obtained.
  37. What are Hounsfield Units/CT number?
    CT numbers represent the attenuation values of different structures within the body according to their atomic number and physical density.

    The CT numbers are assigned a shade of gray corresponding with the attenuation value. For example, the CT number for air is -1000 HU and 0 HU for water. Tissues with densities greater than water have positive CT numbers and those with densities less than water have negative CT numbers.Water is there ference material used because it constitutes 90% of soft tissue mass and is reproducible and easy to obtain.
  38. What is slice thickness?
    • The slice thickness in CT is determined by the collimators.
    • Measurements of slice thickness are determined with a phantom that includes a ramp, spiral, or step wedge in the test objects. The test objects have known measurements and provide a standard with which to compare the scanner.
  39. What is dose and what is its acceptance limits?
    Patient dose varies with slice thickness, kVp, and mAs.

    While no maximum dose limits per patient exam are specified, dose should be kept within 10% of manufacturer specifications.
  40. The Medicare Improvements for Patients and Providers Act of 2008?
    mandates that any nonhospital institution performing advanced diagnostic services such as MRI must be accredited by January 2010 in order to receive Medicare reimbursement.
  41. The CARE bill?
    if passed would provide similar requirements for hospitals as well.
  42. What is center Frequency?
    • Center frequency or resonance frequency is the radiofrequency that matches the static magnetic field.
    • The value for center frequency should be recorded daily.
    • Most manufacturers provide an automated way to determine the resonance frequency.
    • A change in the center frequency indicates that there is a change in the strength of the magnetic field.
  43. What is high contrast resolution?
    • High contrast resolution is the MR system’s ability to resolve small objects.
    • A phantom consisting of pegs, bars, rods, or holes of known sizes is imaged.
  44. What is low contrast resolution?
    • Low contrast resolution is a measure of the system’s ability to differentiate between adjacent tissues having minimal differences in signal intensities.
    • A phantom containing objects of varying size and contrast is used for this test.
  45. What is homogeneity and why is it important?
    the homogeneity of a system’s magnetic field is an indication of the quality or uniformity of its field.

    Poor homogeneity can result in poor image quality and artifacts.

    Changes in homogeneity can be due to ferromagnetic objects located within the bore of the magnet and external ferromagnetic structures that may be in the neighboring magnetic field.
  46. T/F: slice thinkness accuracy is a QC test that is performed in MRI?
  47. What is interslice RF interference?
    Interslice RF interference tests can be used to determine how close slices can be before adjacent slices interfere with each other.
  48. What are the regulation for the fringe field?
    that all spaces over 5 gauss have appropriate warning signs.
  49. What is the purpose of the MQSA was?
    (Mammography Quality standards Act) to standardize mammography quality throughout the U.S.
  50. How long should mammo films be kept?
    must be kept at a facility for either 10 years if the patient never returns for another exam or 5 years if the patient returns regularly
  51. T/F A report in lamen's terms must be sent by the facility to the patient after each exam.
  52. How do DR and CR compare to film/screen in terms of spatial resolution?
    digital has lower spatial resolution than film/screen
  53. How do DR and CR compare to film/screen in terms of contrast resolution?
    digital has higher contrast resolution than film/scree
  54. What is the purpose of Darkroom Cleanliness?
    its objective is to minimize artifacts on films by maintaining the cleanest darkroom possible.
  55. How do we evaluate Darkroom cleanliness?
    it is done in terms of screen cleanliness and lack of artifacts on the films
  56. What are the acceptance limits for sensitometry in mammo?
    • -mid-density and density difference should be within +-.1 of operating level ( if its outside these but within +-.15 films can still be processed that day)
    • -base plus fog should be +-.03OD, no films can be processed
    • -developer temp should be +-.5 degrees
  57. What are we testing for with screen cleanliness?
    objective is to assure that cassettes and screens are free of dust and dirt which cause artifacts.
  58. How do we evaluate screen cleanliness?
    is determined by the presence of artifacts on the film by using a screen cleaner and wiping with camel hair brush or spraying canned air
  59. What are we evaluating with phantom image test with mammo?
    both the mammo machin and the automatic processor (all components of imaging chain)
  60. What are we testing for with screen/film contact with mammo testing?
    assure that optimal contact is maintained between the intensifying screen and the film in each cassette
  61. How do we test screen/film contact with mammo machines?
    putting acrylic sheet on top of compression paddle and bring it to the tube. use manual tech. and view film on a viewbox, look for poor film contact
  62. Why is it important to wait fifteen minutes after loading a cassette for a screen/film contact test in mammo?
    eliminate trapped air
  63. What are the acceptance limits for compression in mammo?
    compression should be between 25 and 45lbs in both the manual and powered mode.
  64. How often should repeat analysis be done in mammography?
    quarterly or at least when 250 patient exams have been completed in low volume clinic
  65. How is viewbox and viewing conditions performed in mammo?
    viewbox surfaces cleaned with window cleaner to remove all strau marks. All making equipment is checked. Illumination level is checked.
  66. What is the purpose of the medical outcomes audit in mammo?
    evaluates the radiologists ability to detect cancer on the mammo films, done by comparing the interpretation of the film to a pathology report.
  67. How do we access AEC performance capability in mammo?
    by taking 3 exposure each of 3 different phantom thicknesses. for ea. phantom thickness, exposures are made using the lowest average and highest kVp clinically used in facility. FOr a given kVp the mAs should increase as the phantom thickness increases.
  68. What is the adverse effects of focal spot conditions being outside acceptance limits in mammo?
    resolution can be effected
  69. How are we measuring entrance skin exposure in mammo?
    • using phantom and dosimeter placed in bucky, compression applied and exposure made. Dosimeter reading and mAs readout are recorded for each exposure.
    • -Average glandular dose is calculated using HVL
  70. What is the purpose of the phantom in ESE testing for MAMMO?
    to simulate the breast
  71. What is it extremely important that alignment in mammography is kept within acceptance limits?
    if outside and miss breast tissue we can possibly miss cancer
  72. What are we testing for with system artifacts in mammo?
    assesed for the presence of artifacts (grids, collimators, compression device, breast support tray, processor artifact)
  73. What is the purpose of Radiation output/why do we measure it in mammo?
    ensures that the unit produces a consistent, uniform beam that has enough energy to produce a quality image.