dmi 63 mobile radiography

  1. where are the portable xray units commonly used?
    • pt room
    • er
    • icu
    • surgery and recovery rooms
    • nursery and neonatal units
  2. when was mobile xray equiment first used?
    • battlefield during WW1
    • units were carried to field sites
  3. are portable units as sophisticated as stationary units?
  4. what are the usual 2 controls on a portable?
    • kvp
    • mas
  5. what is the mas range?
    0.4- 320
  6. what is the kvp range?
    40- 130
  7. what are the two types of mobile x-ray machines/
    • battery powered
    • capacitor discharge
  8. describe the battery powered portable unit
    • uses two different sets of batteries (lead-acid, or nickel- cadmium)
    • one powers driving of machine
    • one set provides power to x-ray tube
    • fully charged batteries can:
    • make 10-15 exposures
    • be driven reasonable distances
  9. describe the capacitor discharge portable unit
    • no batteries
    • carries two metal plates that hold electrical charge
    • capacitor units must be charged prior to each use
  10. what are the advantages and disadvantages of a battery-operated unit
    • Adv:
    • cordless
    • provide constant kvp and mas

    • Disadv:
    • heavy
    • hard to control
  11. what is "deadman" type of break?
    stops machine instantly when push-handle released
  12. what are the advantages and disadvantages of capacitor discharge units?
    • adv:
    • lightweight, smaller and easier to maneuver
    • require much less time to charge than battery units

    • disadv:
    • cant handle thick body parts due to voltage drop during exposure
    • must be charged prior to each use
  13. what is the Nomad?
    • for places with no electricity or chemical processors
    • mainly for dental x-rays
  14. what are the 3 important technical factors that must be clearly understood to perform optimum mobile examinations?
    • grid
    • anode-heel effect
    • SID
  15. what must you consider when using a grid?
    • must be level
    • x-ray beam must be properly centered to grid
    • correct focal distance must be used
    • best grids for mobile rad have ratios of 6:1 or 8:1 and a focal range of 36-44 inches
    • make sure grid is fastened to cassette properly if tape-on grid is used
  16. what must you consider when using anode heel effect?
    • correct placement of anode-cathode (usually marked on tube housing) with respect to anatomy
    • anode should be on thinner part (t-spine)
    • heel effect increases with short SID, large field sizes (more common in mobile radiography
  17. what are the things you should remember when positioning the portable machine?
    • if exam in supine postion, move base of machine to middle of bed
    • if seated upright, base at end of bed
    • lateral and decub positions, place base parallel or perpendicular to bed
  18. what is the single most effective radiation protection measure?
  19. what is the minimal safe distance from beam?
    6 feet
  20. where is the safest place to stand during a portable exam?
    right angle to pt and primary beam
  21. when should you shield pt's gonads?
    • x-raying children
    • person is of reproductive age
    • pt requests
    • gonads lie in or near useful beam
    • when shield will not interfere with anatomy of interest
  22. what is the minimum source to skin distance?
    12 inches
  23. what should you consider when moving a patient?
    • never move pt or part without:
    • assessing ability to move or ability to tolerate movement
    • should also check with staff to obtain assistance and permission to move a part that has had surgery or fractured
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dmi 63 mobile radiography