 | Term | Definition |
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table units |
Fixed-diagnostic only; may have adjustable height Tilting-r&f rooms; may be described by tilting capabilities; fixed height to high for pt. |
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table top |
radiolucent; flat or curved top; smooth easily cleaned hard surface; motor driven or floating |
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table bucky tray |
holds cassettes; grid; phototiming equipment AEC |
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table ancillary equipment |
foot board; shoulder supports; handgrips; compression band |
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types of tube support |
overhead suspension; floor to ceiling; floor suspension; mobile; c-arm; head units; other-mammo, tomo, panoramic, CT, urologic |
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characteristics of overhead suspension |
two sets of ceiling mounted rails; most flexible; most expensive; telescoping column |
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incoming line current |
110-120v @ 60 Hz |
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single phase power |
full wave rectification; 100% voltage ripple; 120 pulsations per sec. |
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three phase power |
incoming full-wave rectified current sequenced at 120 degrees; resulting in a six-pulse waveform; three phase, six pulse,;360 pulses per sec; voltage never drops to zero; three phase, twelve pulse |
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main x-ray circuit |
modifies the incoming power to the proper form to supply the x-ray tube |
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line compensator |
a meter for measure of voltage supplied to unit; control to precisely adjust voltage; automatic on newer radiographic units; in line before autotransformer |
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autotransformer |
supplied with 220v from primary circuit; taps used to alter kVp; voltage provided to autotransformer is the primary voltage; also provides voltage to filament transformer |
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kVp adjustment |
selects appropiate taps on the autotransformer; allows for selection of penetrating power of x-ray beam; pre-reading voltmeter |
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pre-reading voltmeter |
pre-reads voltage before voltage before it goes to high voltage transformer; part of kVp adjustment |
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special circuitry that will evalute the combination of mA, time, and/or kVp section for |
heat loading, and legal exposure limits |
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exposure switch |
anode must bea at correct speed before exposure is taken; exposure switch must be connected to the control console so that operator cannot be exposed (law); equipment is designed to prevent the tube from being manipulated into a position that will expose the operator, exposure switches must be of "dead man" type |
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dead man exposure switches |
finger has to be on switch to continue action |
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timer circuit |
in line on primary side of high voltage transformer |
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types of timer circuits |
mechanical; synchronous; pulse-counting; electronic |
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mechanical timer circuit |
rare, spring driven, inaccurate old |
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synchronous timer circuit |
timing related to frequency of electric current |
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pulse-counting timer circuit |
crystal oscillations at a determined frequency, would vibrate crystals at specific frequnces and the it would measure the # of vibrations |
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electronic |
resistor; length of exposure is determined by the time required to charge a capacitor through a selected variable resistance; time is varied by changing the resistance in the circuit; accurately measure times as short as 1ms |
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most widely used type of timer circuit |
electronic |
