US Physics Test

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US Physics Test
2012-03-12 20:34:43
Quality Assurance Bioeffects

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  1. the routine, periodic evaluation of an US system to guarantee optimal image quality
    Quality Assurance
  2. What are some of the requirements of quality assurance?
    • assessement of system components
    • repairs
    • preventive maintenance
    • record keeping
  3. What are some of the goals of quality assurance?
    • proper operation of equipment
    • detect gradual changes
    • minimize downtime
    • reduce non-diagnostic exams
    • reduce repeat scans
  4. What are the two types of quality assurance devices?
    • tissue equivalent phantoms
    • test objects
  5. What QA device is a fluid filled tank containing stainless steel pins or plastic strings?
    AIUM 100mm Test object
  6. The AIUM 100mm Test object is unable to evaluate?
  7. What does the AIUM 100mm test object evaluate?
    accuracy and performance of a system
  8. What does the AIUM 100mm test object determine?
    • Axial resolution
    • Lateral resolution
    • Electrongic caliper accuracy
    • Dead zone
  9. What QA device is made of graphite-filled aqueous gel or urethane rubber materials?
    Tissue equivalent phantoms
  10. What do tissue equivalent objects assess?
    • Detail and Contrast resolution
    • Penetration
    • Dynamic Range
    • Time Gain Compensation Operation
  11. Tissue Equivalent phantoms have features similar to what?
    soft tissue
  12. What do Tissue Equivalent Phantoms evaluate?
    • grayscales
    • tissue texture
    • multi-focus
    • adjustable focus
  13. What are the characteristics that make tissue equivalent phantoms similar to soft tissue?
    • speed of sound
    • attenuation
    • scattering characteristics
    • echogenicity
  14. This type of QA device will include structures that resemble soft tissue and are imbedded with cysts and solid masses.
    tissue equivalent phantom
  15. What type of QA device includes a circulation pump which propels a fluid through vessels embedded in a tissue equivalent phantom?
    Doppler Phantom
  16. What do doppler phantoms assess?
    • characteristics of all doppler modalities
    • pulsed
    • continuous wave color
    • power mode
  17. Doppler Phantoms may use what as movement?
    • vibrating strings
    • moving belts
  18. Doppler phantoms can produce what type of movement?
    • pulsatile
    • reverse
  19. What are the disadvantages of doppler phantoms?
    presence of bubbles and non-uniform flow
  20. Dopplar phantoms are helpful in determining what?
    accuracy of gate location
  21. What QA device mimics soft tissue and measures the beams geometry perpendicular to the imaging plane?
    slice thickness phantom
  22. What are alternative names for slice thickness phantom?
    elevational resolution or beam profile
  23. ability of a system to display low-level echoes
  24. assessment of the weakest echo that is accurately displayed determined by setting the TGC flat, then increasing system gain from the minimum value to the gain when a deep rod is displayed
    minimum sensitivity
  25. found at a higher gain, all the pins, solid masses, and cystic structures are accurately displayed and adjustments are made to output power, TGC, and amplification
    Normal sensitivity
  26. the output power and amplification are set to the highest practical level, the depth of tissue-like texture is determined
    maximum sensitivity
  27. results from the transducer ringing and the time it takes for the system to switch from transmit to receive, close to the transducer
    dead zone
  28. Which transducers have a thinner dead zone?
    higher frequency
  29. What will help eliminate issues caused by the dead zone?
    acoustic standoff pads
  30. ability to place reflections in the proper position while imaging from different orientations
    registration accuracy
  31. vertical depth calibration places objects correctly parallel to the sound beam
    range accuracy
  32. places objects correctly perpendicular to the sound beam
    horizontal calibration
  33. the effects of the sound beam on the body
  34. What instruments measure bioeffects?
    • hydrophone
    • radiation force
    • acousto-optics
  35. Another name for hydrophone
  36. This bioeffects measuring device has a small hypodermic needle with a tiny piece of PZT attached to an oscilloscope with a wire or may contain a very thin membrane of PZT plastic that is placed in the sound beam
  37. What relates to the pressure of the sound beam when using a hydrophone?
  38. What does a hydrophone do?
    measures pressure at specific locations
  39. Hydrophone measurements are displayed on an?
  40. What can a hydrophone determine?
    • sound beam's shape
    • PRP
    • PRF
    • Pulse duration
  41. From lowest to highest, what would the ultrasonic output be?
    • songraphic (imaging) low
    • M mode and color doppler intermediate
    • Pulsed spectral doppler highest
  42. the measurable force on any target caused by a sound beam
    radiation force
  43. radiation force is also referred to as
    miniature postal scale
  44. interaction of sound and light
  45. this demonstrates the shape of the sound beam in a medium
    Schlieren (shadowing system)
  46. used to measure sound heat, this measures total power through absorption, the beam's total power is calculated by measuring the temperature rise and the time of heating
  47. used to measure sound heat, this tiny electronic thermometer inserted into the sound beam where the temperature is measured. the temperature rise is related to the power at that particular location
  48. used to measure sound heat, this changes color based on the temperature, provided insight into the shape and strength of the sound beam
    liquid crystals
  49. what is meant by the risk-benefit relationship?
    the benefits must outweigh the risks
  50. Is there confirmation of harm resulting from the use of ultrasound at standard intensity?
  51. ALARA
    as low as reasonable achievable
  52. what should techs do to maintain alara
    • lowest output power
    • lowest scan time possible
  53. the science of identifying and measuring the characteristics of an ultrasound beam that are relevant to its potential for producing biological effects
  54. research performed within the living body
    in vivo
  55. research performed outside the living body in an artificial environment
    in vitro
  56. is it ethical to do all studies in vivo?
  57. searches for a relationship between cause and effect
    mechanistic approach
  58. searches for a relationship between exposure and response
    empirical approach
  59. 2 mechanisms of bioeffects
    • thermal
    • cavitational
  60. bioeffects resulting from tissue temperature elevation
  61. a calculated number useful in predicting max temperature increases under clinically relevant conditions
    thermal index
  62. 3 forms of measurement of in vivo tissue temperature changes that are the best
    • TIS soft tissue
    • TIB bone
    • TIC cranial bone
  63. absorption occurs more frequently and at a higher degree in what?
  64. what tissues are less tolerant of tissue heating
  65. how many hours will it take of US exposure to elevate the temperature 2 degrees celcius
    50 hours
  66. Tissue heating is related to what type of intensity
  67. What is worse a focused or unfocused US beam?
  68. interaction of sound waves with microscopic, stabilized gas bubbles in tissues
  69. 2 forms of cavitation
    • stable
    • transient
  70. this type of cavitation occurs at lower MI levels, gaseous nuclei tend to oscillate (expand and contract) bubble don't burst
  71. this type of cavitation occurs at higher MI levels, bubbles burst, and produces highly localized violent effects such as colossal temperatures and shock waves
  72. what is inertial or normal cavitation
  73. related to the likelihood of harmful bioeffects from cavitation, unitless, related to peak negative pressure and frequency, greater likelihood of cavitation bioeffects with additional negative pressure and lower frequencies
    mechanical index
  74. exposure-response population studies ultilizing clinical surveys, many dealing with in utero fetal exposure
  75. 3 limitations of epidemiology studies
    • retrospective studies
    • ambiguities may exist in the data
    • other risk factors may lead to bad fetal outcomes
  76. what make up the best epidemiologic studies?
    prospective and randomized
  77. information is documented as it occurs
  78. creates a control group, takes other risk factors into account
  79. epidemiologic data indicates that ultrasound exposure is not associated with adverse what?
    fetal outcomes
  80. greatest risk in ultrasound is from?
    electrical safety (cracked transducer housing)
  81. How should electrical hazards be assessed?
    visually check equipment