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86 Cards in this Set
- Front
- Back
What is the function of the xray system?
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To provide a controlled flow of electrons intense enough to produce an xray beam appropriate for imaging
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What are the three components of the imaging system?
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1) xray tube
2) operating console 3) high voltage generator |
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What does the operating console control?
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1) the voltage applied to the xray tube
2) the current through the xray tube 3) the exposure time |
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What major parts does the high-voltage generator contain?
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1) high-voltage step up transformer
2)rectification circuit |
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What is the range of Voltage for most diagnostic xray imaging systems?
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Voltage Range
25 - 150 kVp |
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What is the general range of tube current for most diagnostic xray imaging systems?
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Current Range
100 - 1200 mA |
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What is Peak kilovoltage controlled by?
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A series of electric taps on the autotransformer.
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How many windings does an autotransformer have?
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One
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What modes can an autotransformer work in?
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Step-Up Mode or
Step-Down Mode |
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Where does the power to the primary side of the high voltage tranformer come from?
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Secondary side of the autotransformer
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What is the relationship of output voltage from the autotransformer to the turns ratio?
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Proportional to the turns ratio
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What is the principial purpose of the autotransformer?
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to Increase Voltage
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What type of energy does the autotransformer convert?
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Electrical Energy
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What type of energy does the autotransformer convert electrical energy into?
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Electrical Energy
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What is the principal purpose of the high-voltage transformer?
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Increase Voltage
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The voltage supplied to an x-ray imaging system is 220V. What is used to supply the voltage used by the xray tube?
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the High Voltage Transformer
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In the design of the autotransformer how many coils serve as the primary and secondary coils?
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A single coil
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What requires that constant voltage be supplied to the autotransformer?
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Selection of kVp
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What is required to stablize voltage?
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Line Compensation
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What is used to determine voltage before exposure?
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An autotransformer
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What is directly connected to the autotransformer?
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the kVp meter
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What are the taps on the windings of an autotransformer used to select?
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Line Compensation
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Where is the meter that monitors xray tube current physically located?
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on the Control Console
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What effect does the filament transformer have on current?
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It INCREASES current
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Where is the filament transformer usually located?
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with the High Voltage generator
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Where does the filament circuit begin and where does it end.
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It begins at the filament transformer and ends at the filament.
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What is the turns ratio of the filament transformer?
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< 1
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By what unit is Xray tube current is usually measured?
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mAs
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What are exposure timers?
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Precision devices that start and stop xray production.
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What are the four basic types of exposure timers
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1) Mechanical
2) Synchronous 3) Electronic 4) mAs |
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Describe a mechanical timer.
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1) Operates by spring action
like a hand wound alarm 2) not very accurate 3) not used in modern equipment |
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Describe synchronous timers.
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1) use a synchronous motor that operates @ 60 rps
2) shortest possible exposure time 1/60 s |
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Describe electronic timers
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1) operates on an electronic resistive-capacitive circuit based on the time required to charge a capacitor
3)timers are accurate 4) allow exposure as short as 1 ms 5) can be used for serial radiography |
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Describe mAs timers
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1) electronic timers that monitor the product of mA and time
2) terminate exposure when proper mAs is reached |
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What is AEC?
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Automatic Exposure Control
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Describe Automatic Exposure Control.
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A radiation measuring device that terminates the xray exposure when enough radiation reaches the image receptor.
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CONTROL of the EXPOSURE TIME is always on what side of the high-voltage transformer?
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PRIMARY side
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The exposure timer on a three-phase radiographic imaging system will be ..
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electronic
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What uses an ionization chamber between the patient and the image receptor?
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An automatic exposure control (AEC) device.
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What device requires a BACKUP TIMER?
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An automatic exposure control (AEC) device.
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What measurement expresses xray tube current?
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coulombs/second
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What is required when designing an mA station?
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Precision resistors
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What does the control of focal spot size depend on?
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the ENERGIZED filament
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mA is a unit of ...
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electric current
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mAs is a unit of ...
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electric charge
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What is in the high-voltage SECTION of the xray imaging system.
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1) high voltage transformer
2) filament transformer 3) rectifier circuit |
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Describe the function of the high voltage transformer.
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converts low voltage from the autotransformer to the required kVp
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Describe function of the filament transformer.
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reduces the voltage from the autotransformer to about 10V for heating the filament. At the same time the filament current is regulated to the range of 4 - 10A.
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Describe the function of the rectifier circuit.
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converts the alternating voltage into a direct voltage before use by the xray tube.
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What type of rectifier is contained in a typical high-voltage generator?
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Diode rectifier
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Pulses per second for Half-wave
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6o
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Pulses per second for Full-Wave
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120
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Pulses per second for Three-phase, 6 pulse
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360
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Pulses per second for Three phase, 12 pulse
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720
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Pulses per second for High Frequency
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up to 1000
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Percentage Ripple for Half-wave
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100
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Percentage Ripple for Full-wave
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100
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Percentage Ripple for Three-phase, 6 pulse
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13
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Percentage Ripple for Three phase, 12 pulse
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4
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Percentage Ripple for High Frequency
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1
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What does a change in voltage waveform from the primary side to the secondary side of the high voltage transformer produce a change in?
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Amplitude
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What control is used to raise or lower the VOLTAGE in the high voltage circuit?
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kVp Selector
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What level of voltage flows through the filament of the xray tube?
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low voltage
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What selector controls the filament circuit?
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mA selector
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Which side of the step-up transformer has more windings?
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the secondary circuit side
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The rectifiers are part of whih xray circuit?
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the secondary circuit
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The xray tube current is controlled by the ...
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Filament current
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The changing of alternating current to direct current is known as
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rectification
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What is the name of the closed path over which electric curret flows.
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Circuit
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What controls the incoming voltage to the autotransformer?
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Main breaker switch
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Which type of rectification will supply the xray tube with the greatest power?
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Full Wave
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What is the voltage supplied to the autotransformer called:
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Line Voltage
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WWhat is the most accurate timer?
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Electronic
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If the line voltages changes because of demands by other users, adjustments must be made in the ....
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voltage compensator
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What is the current indicated by the milliammeter?
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tube current
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Tapping the windings of the autotransformer to supply voltage to the stepup transformer is the pulse of ...
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the kVp Selector
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What is an advantage of three phase equipment over single-phase equipment?
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can achieve shorter exposure times
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Where in the xray circuit is the timer located?
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between the autotransformer and the step-up transformer.
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What type of current suppplies the xray tube?
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Pulsating direct current
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What is placed in a circuit in case the current surges during the exposure?
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Breaker Switch
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What test can be used to determine the accuracy of the rectification circuit and/or timer circuit?
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Spinning Top Test
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Examination tables and the xray tube can be angles and moved in various ways to allow..
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1)easy positioning of the patient
2) very controlled exposure of the desired body areas |
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A suspension systems that holds the tube on one end of the arm and the image receptor on the other is called
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C-Arm
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The operating console contains circuits that are
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Low Voltage only
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Most mammography units operate with .... generators
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High Frequency
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The main function of the primary circuit is to ...
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Step up the AC volatage to the secondary circuit.
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