Card Set Information

2015-07-01 21:08:40
Quality Assurance
RVS exam
RVS Exam
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  1. Quality Assurance
    • -Ensures the standard of quality are being measured & demonstrate acceptable results
    • -Statistical analysis
    • -Primary focus is the Accuracy of the results of Vascular exam
    • -Any Non-invasive test s/b compared to a reference test known as 'GOLD STANDARD'
    • -Strive for the highest accuracy as possible
    -Ability of a test/exam to detect disease when it is really present

    *Sonogram & Venogram both found thrombus

    -Ability of a test/exam to indicate that NO disease is present when there is NO disease

    *Neither the sonogram nor venogram found thrombus

    -Meas the likelihood (%) that a + Noninvasive test/exam is correct when disease is actually present

    -Meas the likelihood (%) that a - Noninvasive test/exam is correct when NO disease is present

    -Measures percentage (%) of ALL non-invasive tests/exam that correctly correlate w/ the Gold Standard Exam

    *Overall Accuracy must be a % that falls betw Sensitivity & Specificity & betw +PV & -PV
    -% of population affected by a specified disease @ a give time
  8. Diameter Reduction
    • -Distance across the CTR of a Circular structure
    • -ART stenosis is reported in % diameter

  9. Area Reduction
    • -Size of a region w/in its set boundaries
    • -Calculated on a TRV image @ the level of Maximum stenosis using measurements of RL diameter & TL diameter

    • -For stenoses that are Uniform & Circumferential use these values:
    • -50%DR=75%AR
    • -75%DR=94%AR
    • -90%DR=99%AR
  10. NASCET
    • -Eval Efficacy of medical therapy vs surgical intervention in prevention of stroke in symptomatic indiv w/ atherosclerotic changes causing stenosis
    • -RL Diameter @ the point of maximum stenosis divided by diameter of ICA in a distal non-diseased location

  11. ECST
    • -Established criteria for angiographic meas locations for calculation of % stenosis
    • -RL diameter @ point of maximum stenosis divided by "estimated" TL diameter @ same location as maximum stenosis

    -Recommendation for endarterectomy for asymptomatic pts w/ >77% diameter reducing stenosis
  12. Instrument Performance
    • -Detects image quality problems & assure proper operation of equipment
    • -QA testing is usually performed on a monthly basis w/ ultrasonic test phantoms & visual inspection of equipment & Tx
  13. Test Phantoms-AIUM
    • 1. AIUM: American Inst of U/S 
    • -Composed of stainles steel rods arranged in grps
    • -Parameters meas:
    • -Dead zone
    • -Axial/Lateral Res
    • -Range accuracy (Vert depth/Horizontal calib)
    • -TGC
    • -Uniformity
    • -System sensitivity
  14. Test Phantoms-Tissue Equivalent Phantom
    • -Tissue mimicking medium (gel) w/ mock cysts & lesions of various diameters
    • -Temperature sensitive
    • -Gray scale s/b matched against gray scale bar on monitor
    • -Parameters meas:
    • -Dead zone
    • -Range accuracy
    • -Detail Res (Axial, LAT, Slice thickness/Elev Res)
    • -TGC
    • -System Sensitivity
    • -Contrast Res (Dynamic Range)
  15. Evaluation of Doppler Quality
    • -Assess accuracy of Doppler meas
    • 1. Doppler flow phantoms
    • 2. String phantom
  16. Doppler Flow Phantom
    • -Contain a tube (simulated vessel) embedded in a tissue mimicking medium
    • -Tube connects to a pump w/c pushes fl thru the tube @ adj Vel. Fl contains reflectors like RBCs
    • -Simulated vessel is positioned @ various angles used to eval Doppler angle cursor
  17. String Phantom
    • -Uses string that moves on pulleys in a water bath
    • -String Vel is closely regulated & provides vel standard
    • -Allows for accurate assessment of flow vel 
    • -Parameters eval:
    • -Flow angle indicators
    • -Doppler SV
    • -Wall filters
    • -Sensitivity
    • -Appropriate gain
    • -PRF
    • -Angle correction
  18. Preventative Maintenance (PM)
    • -Equipment should have routine preventative maintenance for performance & safety
    • -Service personnel fr manufacturer
    • -Sonographers=daily wipe down & clean tx
    • -Gel warmers s/b evaluated
    • -Ancillary equipments (ie VCR, printer, monitor)
    • -Pt equipment as well (ie foot stools, table, chairs)
  19. Biological Effects-ALARA
    • -As Low As Reasonably Achievable
    • -American Institute of U/S in Medicine (AIUM) states potential benefits & risks of ea exam s/b considered.  
    • -ALARA s/b observed when adj controls 
    • -Power, Intensity & Time are the main determinants of ALARA
    • -Exposure can be ↓ : keeping power output low, Raise Gain to keep power low, ↓ exam time
  20. Cavitation
    • -Can produce biological effects
    • -Interaction of sound waves w/ microscopic gas bubbles in tissue
  21. Mechanical Index (MI)
    • -Acoustic output in terms of likelihood of cavitation
    • -MI s/b @ 1 or below
    • -Can occur fr heat or absorption in tissue
    • -When sound is absorbed, energy is converted to heat
    • -Cavitation has not been proven w/ (I) used for diagnostic sonographic purposes
  22. Thermal Index (TI)
    • -Ratio of acoustic power produced by Tx to the power required to raise tissue temp by 1oC 
    • -Equipment manufacturers are required to display T1
    • -AIUM recommends T1 NOT to exceed 2o 
    • -Effects of MI & TI can be reduced by not prolonging scanning times
  23. Scientific Data
    • -In vivo=Studies involve animals & plants
    • -In vitro=studies are experiments performed on cells or tissues in artificial environment like a test tube or culture media (petri dish)
    • -Epidemiological=Long-term studies of distribution & causes of diseases & inj in human populations
  24. Preventing Electrical Hazards
    • -Precautions such as proper electrical grounding should always be taken to avoid electrical shock to the pt & you
    • -Inspect machine & surrounding environment to ensure a properly working equipment
    • -Frayed or damaged power cable s/b repaired or replaced