Term
| what are the 3 basic parts of the x-ray imaging system |
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Definition
| operating console, x-ray tube, high-voltage generater |
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Term
| what does the operating console do |
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Definition
| allows for control of line compensation, kVp, mA, and exposure time |
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Term
| what is line compensation |
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Definition
| measures and controls the voltage required by the system (modern ones are automatic and require no adjustment) |
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Term
| what are the three parts of the operating console |
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Definition
| line compensation, autotransformer, exposure timers |
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Term
| what does the autotransformer do |
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Definition
| with a single winding wire, it supplies precise voltage to filament and high-voltage circuit |
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Term
| what do the primary connections do and how many are there |
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Definition
| supply power to the autotransformer and there are 2 |
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Term
| what do the secondary connections on the autotransformer do |
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Definition
| allow for variable output (this is how kV is selected) |
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Term
| how much is the autotransformer designed to step up the voltage |
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Definition
| to twice the input of the voltage value |
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Term
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Definition
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Term
| what happens when the autotransformer supplies power to the filament circuit |
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Definition
| it heats it up thereby releasing electrons (thermionic emission) |
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Term
| what does the filament circuit control |
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Definition
| tube current (the more electrons that are boiled off, the higher the tube current) |
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Term
| what happens once the mA has been selected |
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Definition
| voltage from the mA selector is then delivered to the filament transformer |
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Term
| what kind of transformer is the filament transformer |
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Definition
| a step down transformer... decreasing voltage so that current can be increased (normally operate at 3-6 amps) |
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Term
| what are the five types of exposure timers |
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Definition
| mechanical, electronic, mAs, synchronous, and automatic exposure control |
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Term
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Definition
| spring type, no longer used |
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Term
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Definition
| minimum exposure time is 1/60th sec (AC supplied) |
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Term
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Definition
| terminates the exposure when the desired mAs value is attained |
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Term
| automatic exposure control (AEC) |
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Definition
| measures the quantity of radiation reaching the image receptor. Terminates exposure when IR gets enough radiation for optimum density |
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Term
| what do they use for exposure timer checks |
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Definition
| solid state radiation detectors- based on quartz-crystal oscillator, can measure times as short as 1 ms |
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Term
| what are the three parts of the high-voltage generator |
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Definition
| high-voltage transformer (step-up), the filament transformer (step-down), and rectifiers |
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Term
| what is voltage rectification |
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Definition
| the process of converting AC to DC |
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Term
| voltage rectification is required to make electrons flow which way |
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Definition
| from cathode to anode only |
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Term
| rectification uses what types of diodes |
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Definition
| vacuum tube and solid-state |
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Term
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Definition
| same waveform as voltage supplied to the high-voltage transformer, except with a higher amplitude |
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Term
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Definition
| the wave can't swing negatively (inverse voltage is removed) |
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Term
| how many diodes does a half-wave rectification have |
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Definition
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Term
| disadvantages of half-wave rectification |
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Definition
| wastes half the supply of power and requires twice the exposure time |
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Term
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Definition
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Term
| how many diodes does a full wave rectifier contain |
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Definition
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Term
| how many times a second does the pulsed x-ray occur in full wave rectification |
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Definition
| 120 times (cuts exposure time in half) |
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Term
| disadvantage of single phase power |
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Definition
| waveform has a value near zero which has little diagnostic value (low energy, low penetrability) |
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Term
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Definition
| three simultaneous voltage waveforms, maintains a nearly consistent high voltage and never drops to zero |
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Term
| how many pulses in three phase power |
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Definition
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Term
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Definition
| converts 60hz to 500-25,000hz, nearly constant potential voltage, improves image quality at lower patient dose |
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Term
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Definition
| single-phase=> varies from zero to max |
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Term
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Definition
| three-phase, six pulse=> voltage never falls below 86% of max |
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Term
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Definition
| three=phase, 12 pulse=>voltage never falls below 96% of max |
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Term
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Definition
| high frequency generator=> higher x-ray quality and quantity |
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