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Radiography Digital Age > X-RAY MACHINE CIRCUITS AND GENERATORS Ch 8 > Flashcards

X-RAY MACHINE CIRCUITS AND GENERATORS Ch 8 Flashcards

1
Q
  1. The main circuit of an x-ray machine is composed of what three general sections:
  2. __________________________________________
  3. __________________________________________
  4. __________________________________________
A

Console
High Voltage
X-ray tube circuit

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2
Q
  1. To protect the entire x-ray machine circuit, a large circuit _____________________ kicks off if there is an overload or short circuit in any part of the system.
A

Breaker

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3
Q
  1. A device which measures the incoming voltage from the power line, and compensates for variations by adjusting the autotransformer slightly up or down, is called the _____________ __________________ __________________________.
A

Line Voltage Compensator

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4
Q
  1. The ____________ (major and minor) controls on the x-ray machine console actually set the autotransformer.
A

kVp

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5
Q
  1. The high voltage transformer is a step-up transformer with a turns ratio normally between ___________ and _____________.
A

500:1, 1,000:1

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6
Q
  1. Before and after passing through the step-up transformer, the only difference in the two AC waveforms for the electricity is the ____________________ of the waves, which indicates increased voltage.
A

amplitude

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7
Q
  1. For full efficiency, a minimum of ____________ diode rectifiers is required in the
    rectifier bridge used in a single-phase x-ray machine.
A

4

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8
Q
  1. The modern solid-state diode is constructed by connecting an ________-type
    crystal of silicon to a _________-type crystal.
A

N, P

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9
Q
  1. As long as electrons and holes are huddled together along the n-p junction, a _________________________ bridge is formed and electricity can flow through the diode.
A

potential

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10
Q
  1. When AC current reverses direction, it _______________________ the diode with the holes at one end and the electrons at the opposite end, such that electricity cannot flow through the diode.
A

polarizes

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11
Q
  1. It is important that ____________________________ be the last step in preparing high-voltage electricity to enter the x-ray tube.
A

rectification

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12
Q
  1. In Coolidge’s hot-cathode x-ray tube, the process of __________________________ _______________________ frees electrons from the filament wire prior to exposure, which greatly improves efficiency.
A

thermionic emission

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13
Q
  1. To heat the filament wire by friction between electrons, what is needed is high- _______________________ current forced into a very thin wire.
A

amperage

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14
Q
  1. The filament current is applied whenever the _________________ button is held down at the console.
A

rotor

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15
Q
  1. Once the “rotor” button is pushed, a delay is necessary before exposure can be made because it takes a few seconds for the high-amperage current to _______________ the filament.
A

heat

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16
Q
  1. Excessive rotoring can cause unnecessary _______________ and _______________ to the x-ray tube filament, reducing x-ray tube life.
A

wear, tear

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17
Q
  1. The step-down transformer in the filament circuit usually has a turns ratio of
    __________ to produce a current of up to 5 amps (at 5 volts).
A

1:44

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18
Q
  1. Because the filament current enters one end of the filament and exits the other (and does not jump across the x-ray tube, it is unnecessary to _______________________ the filament current.
A

rectify

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19
Q
  1. On most x-ray machines, selection of an mA station taps the filament current to pass through a particular electronic ________________________.
A

resistor

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20
Q
  1. Any meter placed in series in a single wire must measure ________________________.
A

amperage

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21
Q
  1. A voltmeter must be connected in parallel because it _______________________ the electrical flow between two points in the circuit.
A

compares

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22
Q
  1. To avoid the hazard of high voltage shock at the x-ray machine console, a ____________________________ voltmeter is used.
A

pre-reading

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23
Q
  1. The mA meter on the console measures the milliamperage of the current which actually flows ___________________ the x-ray tube.
A

across

24
Q
  1. The number of electrons “boiled off” of the filament and passing across the x-ray tube, (the tube current), is but a _____________________ of the current passing through the filament itself, (the filament current).
A

fraction

25
Q
  1. To measure tube current, the mA meter must be connected in the main circuit between the ___________________________________ and the ___________________________.
A

step up transformer, x-ray

26
Q
  1. Practice: Make a sketch here of the entire x-ray machine circuit, as best you can,
    from memory:
A

?

27
Q
  1. An x-ray machine with no rectifiers in its circuits is referred to as __________-rectified.
A

self

28
Q
  1. In a half-wave rectified system, all the rectifiers do is _________________ those
    pulses of electrical current which are going the wrong way.
A

block

29
Q
  1. Because self-rectified and half-rectified units provide only 60 pulses of current to the x-ray tube per second, radiographic techniques must be ____________________ when compared with a fully-rectified single-phase x-ray machine.
A

doubled

30
Q
  1. The average kilovoltage for a single-phase x-ray machine is approximately _____________ of the peak kilovoltage.
A

one-third

31
Q
  1. For three-phase x-ray machines, during an exposure the voltage never drops to ________________.
A

91%

32
Q
  1. For a three-phase x-ray machine, the fluctuation of the voltage between 86% and 100% of the set kVp is called voltage _______________________.
A

ripple

33
Q
  1. For a three-phase x-ray machine, the average voltage is about ____________% of the kVp set.
A

91

34
Q
  1. The increased effective voltage of a three-phase machine provides higher overall _________________________ for the x-ray beam, which results in more exposure reaching the detector plate or cassette.
A

penetration

35
Q
  1. In addition, because of overlapping pulses of electrical current for a three-phase machine, for a given set mA station the effective mA is ______________________.
A

increased

36
Q
  1. Combining both of the foregoing, for practical purposes, the mAs may be approximately cut to _________________ for any three-phase machine when compared to a single-phase machine.
A

half

37
Q
  1. For a 3-phase, 12-pulse machine, the voltage ripple is reduced to ____________%.
A

94%

38
Q
  1. High-frequency generators alter the waveform of the electrical current and convert it from 60 hertz to a much higher frequency ranging from ________ to ________ Hz.
A

500, 25,000 Hz

39
Q
  1. For high-frequency mobile x-ray machines, 8 to 10 less kVp can be set for torso procedures because the average kV is nearly _________________ to the kVp set.
A

equal

40
Q
  1. Higher-power generators with mA stations as high as 800 to 1200 mA are recommended for pediatric and interventional radiography, because they allow exceedingly _________________ exposure times.
A

short

41
Q
  1. The electrical power rating of a generator or transformer is used as an indication of its overall quality, and is normally expressed in units of ____________________.
A

kW

42
Q
  1. Write here the formulas to calculate the generator power ratings for:
    A three-phase x-ray machine: _____________________ A single-phase x-ray machine: _____________________
A

mA x kVp / 1,000

0.7 mA x kVp / 1,000

43
Q
  1. Synchronous motor exposure timers have a minimum exposure time of __________ second, and all available exposure times are multiples of 1/60.
A

1/60th

44
Q
  1. ______________________ timers are the most common type and use capacitors to measure the electric charge accumulated.
A

Manual

45
Q
  1. Electronic timers are extremely accurate and can produce exposure times as short
    as __________ millisecond.
A

1

46
Q
  1. Commonly found on mobile x-ray units is the _____________ timer.
A

mAs

47
Q
  1. The first automatic exposure terminating device was the _______________________.
A

Photo timer

48
Q
  1. In most automatic exposure control (AEC) systems, the radiation detection device is a gas ____________ _____________________.
A

ion chamber

49
Q
  1. In an AEC circuit, device called a _______________________ presets the amount of charge the capacitor will hold before it is discharged to shut down the exposure.
A

thyratron

50
Q
  1. The surge of electricity discharged from the capacitor is used to energize an ____________________________ which pulls the switch in the main circuit open to terminate the exposure.
A

electromagnet

51
Q
  1. The AEC circuit does not “time” anything—all it knows how to do is _________________ electrical charge, and shut off the exposure when the pre-set amount is reached.
A

count

52
Q
  1. Anything which reduces the ________________ of x-rays reaching the detectors behind the patient, such as rolling the patient onto his/her side, results in a longer time for the charge limit to be reached.
A

rate

53
Q
  1. The ______________________ control is the only logical way to alter the resulting exposure while using the AEC.
A

density

54
Q
  1. The “density” control for an AEC system alters the _____________________ higher or lower by set amounts (usually steps of 25%).
A

thyratron

55
Q
  1. The AEC system can automatically compensate for any changes that occur in ____________________ of the tabletop, but has no way of “knowing” when grids, cassettes, and detector plates that lie ____________________ the AEC detectors have been changed.
A

front, behind

Radiography Digital Age (2 decks)

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