110quiz3

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speedyvincent
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174063
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110quiz3
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2012-09-28 01:51:05
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110quiz3
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  1. Personal monitoring when
    a worker may receive 10%/5000millirem a year or more annual MPD
  2. typical monitoring is done when
    1% is expected
  3. placement
    • collar level
    • outside of apron
    • if pregnant at waist
    • extremity monitors also
  4. Film badges
    • 10mremto 500 rem
    • cheap
  5. OSL opic sensitive luminesnce
    • aluminum oxide read by laser
    • worn for 2 months
    • 1mrem and sensitive to 5kev to 40Mev of energy
  6. TLD Thermal luminscent dosimeter
    • Lithium floride
    • reasonably sensitive
    • cannot be re-read
    • pocket ionization chambers
    • good for immediate feedback

    not reliable-sensitive to mechanical energy
  7. Dosimetry reports
    • deep
    • eye
    • shallow doses
  8. patient protection
    • -effective communication
    • verbal messages
    • concise instructions
    • appropriate communication
  9. voluntary motion
    • voluntary motion
    • -lack of control
    • -immobilization devices work with this group
  10. involuntary motion
    • -fast exposure times with high mA helps
    • -possible increasing kVp will help
    • 15% rule shorter exposure
    • fast film/screen combinations
  11. Beam limiting devices
    diaphragms,cones,collimators,

    • limit the amount of tissue the beam exposes
    • limit scatter produced
  12. variable collimator
    • 2 sets oflead shutters limit the divergence of the beam
    • -+ 2% of SID
  13. Positive beam limitation PBL
    automatic collimator, collimates to the field size put in the bucky tray
  14. Total Filtration
    inherent plus added filtration
  15. inherent
    • glass envelope
    • oil
    • window of the tube housing
    • 0.5 mm Al
  16. Added aluminum
    added to meet requirements
  17. Total Filtration Al
    • 2.5mm Al > 70kvp
    • 1.5mm Al 50 - 70kvp
    • 0.5 mm Al < 50kvp
  18. Mobiles/portables and fluoro units req to have
    atleast 2.5mm Al
  19. Half Value Layer HVL
    amt of aluminum req to reduce the beam intensity to half its original value.
  20. as kVp is increased
    • the penetrability if the beam increases,
    • the amt of Al necessary to halve the beam intensity will have to increase as well
  21. Protective shielding
    • Gonadal shields
    • gonads shields needed when they are within 5cm of the beam
    • -unless shielding will obscure anatomy
    • req to have atleast 0.5 mm Pb
  22. types of Gonadal shields
    flat contact,shadow,shaped contact, clear lead
  23. specific area shielding
    • breast during scoliosis screening
    • clead lead filter
    • PA instead of AP
  24. compensating filters
    trough or bilateral wedge - for chest images

    wedge filter, special metal filters; copper
  25. Technical factors
    • high kvp low mas techniques
    • specific body part or region - lowest dose to patient
  26. film processing and QC
    QC insures that the processor is maintained to a stanndard level of acceptance
  27. film/screen
    • rare earth screens are generally faster.
    • occurs due to their higher atomic number results in higher absorption of photons. more light produced per photon
  28. Grids
    • prevents scatter radiation from reaching film
    • increase PT dose; higher contrast
    • quality dramatically improved

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