dmi 63 mobile radiography
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where are the portable xray units commonly used?
- pt room
- surgery and recovery rooms
- nursery and neonatal units
when was mobile xray equiment first used?
- battlefield during WW1
- units were carried to field sites
are portable units as sophisticated as stationary units?
what are the usual 2 controls on a portable?
what is the mas range?
what is the kvp range?
what are the two types of mobile x-ray machines/
- battery powered
- capacitor discharge
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
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
what are the advantages and disadvantages of a battery-operated unit
- provide constant kvp and mas
- hard to control
what is "deadman" type of break?
stops machine instantly when push-handle released
what are the advantages and disadvantages of capacitor discharge units?
- lightweight, smaller and easier to maneuver
- require much less time to charge than battery units
- cant handle thick body parts due to voltage drop during exposure
- must be charged prior to each use
what is the Nomad?
- for places with no electricity or chemical processors
- mainly for dental x-rays
what are the 3 important technical factors that must be clearly understood to perform optimum mobile examinations?
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
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
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
what is the single most effective radiation protection measure?
what is the minimal safe distance from beam?
where is the safest place to stand during a portable exam?
right angle to pt and primary beam
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
what is the minimum source to skin distance?
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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