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Physics > Ch 5 The X-Ray Imaging System > Flashcards

Ch 5 The X-Ray Imaging System Flashcards

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1
Q

fluoroscopic couches tilt ___ to the foot side and ___ to the head side

A

90; 30

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2
Q

3 parts of the x-ray system:

A

x-ray tube, operating console & high-voltage generator

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3
Q

radiation quantity:

A

the number of x-rays or intensity of the x-ray beam, mGya or mGya/mAs

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4
Q

radiation quality:

A

penetrability of the beam, kVp or half-value layer (HVL)

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5
Q

most x-ray imaging systems operate on ___ of power

A

220V

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6
Q

voltage can vary by as much as ___

A

5%

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7
Q

line compensator:

A

measures the voltage provided to the x-ray imagining system and adjusts that voltage to 220V

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8
Q

the power supplied to the x-ray system is first delivered to the _____

A

autotransformer

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9
Q

*the autotransformer has a ____ and is designed to ___

A

single winding and is designed to deliver precise voltage to the filament circuit

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10
Q

in the autotransformer the voltage it receives (primary) and the voltage is provides (secondary) are:

A

directly proportional to the number of turns in the transformer

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11
Q

minor kilovolt peak:

A

“fine tunes” the selected technique

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12
Q

*kVp determines the:

A

quality of the x-ray beam

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13
Q

pre-reading kVp meter:

A

allows the voltage to be monitored before an exposure

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14
Q

*thermionic emission:

A

the release of electrons from a heated filament

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15
Q

x-ray tube current if controlled through:

A

filament circuit

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16
Q

in a falling load generator exposure; the result is:

A

begins at the maximum mA and the mA drops as the anode heats, the result is minimum exposure time

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17
Q

*mAs aka _____

A

electrostatic charge (C)

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18
Q

guard timer will:

A

terminate an exposure after a prescribed time, usually 6s

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19
Q

in synchronous timers the minimum exposure time is ___

A

1/60s

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20
Q

*most exposure timers are:

A

electronic and are controlled by a microprocessor & are accurate to milli seconds (.001s)

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21
Q

*mAs timers are used on:

A

falling load and capacitor discharge imaging systems

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22
Q

AEC:

A

automatic exposure control, measures the quantity of radiation that reaches the IR and terminates the exposure when it receives the required radiation

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23
Q

*high-voltage generator has 3 primary parts:

A

high-voltage transformer, filament transformer & rectifiers

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24
Q

turns ratio is the:

A

number of secondary windings to the number of primary windings

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25
Q

voltage is ____ proportinal to the number of turns

A

directly

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26
Q

current is ____ proportional to the number of turns

A

indirectly

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27
Q

the turns ratio of high-voltage transformers are:

A

500:1 or 1,000:1

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28
Q

*transformers will only operate on ___

A

AC

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29
Q

the only difference between primary and secondary wavelengths is ____

A

amplitude

30
Q

primary voltage is ___
secondary voltage is ___

primary current is ___
secondary current is ____

A

V
kV

A
mA

31
Q

a common wall plug is ___ Hz and ___ changing direction ____

A

60 Hz and AC changing direction 120 times a second

32
Q

an x-ray tube is ____

A

DC

33
Q

*rectification is:

A

the process of converting AC to DC

34
Q

a rectifier is:

A

a electronic device that allows current flow in only one direction

35
Q

*voltage rectification is required:

A

to ensure that electrons flow from x-ray tube cathode to anode only

36
Q

rectification is accomplished with _____

A

diodes

37
Q

a diode contains:

A

two electrodes

38
Q

n-type semiconductors have:

A

loosely bound electrons that are relatively free to move

39
Q

p-type semiconductors have:

A

spaces or “holes” where there are no electrons

40
Q

half-wave rectification is ______; the result is ______; uses ___ diodes

A

the inverse voltage is removed from the supply of the x-ray tube by rectification; the result is a series of positive pulses separated by gaps; only half the AC waveform appears in the output; has 0, 1, or 2 diodes

41
Q

during the positive portion of AC waveform ______; during negative portion of AC waveform ______

A

the rectifier allows electric current to pass; the rectifier does not conduct (no current)

42
Q

full-wave rectification is ______; the output voltage is ____; exposure time is _____

A

the negative half of the AC waveform is reversed so the anode is always positive, current is shown during both the positive and negative phases; output voltage is positive with no gaps; exposure times halved

43
Q

single-phase power results in:

A

a pulsating beam

44
Q

three-phase power has:

A

multiple waveforms superimposed on each other resulting in a waveform that maintains nearly a constant high voltage

45
Q

three-phase power has __ pulses per ____ sec

A

6; 1/60

46
Q

*with 3 phase power the voltage applied across the x-ray tube is:

A

nearly constant, never dropping to 0 during exposure

47
Q

SCR’s:

A

silicon-controlled rectifiers

48
Q

*full wave rectification or high-frequency voltage generation is used in:

A

almost all stationary x-ray imaging systems

49
Q

*during capacitor discharge the voltage:

A

falls approximately 1kV/mAs

50
Q

single-phase power has ___ voltage ripple

A

100%, voltage varies from 0 to the maximum value

51
Q

3 phase 6 pulse power has ___ voltage ripple

A

14%, the voltage never falls below 86% of the maximum value

52
Q

3 phase 12 pulse power has ___ voltage ripple

A

4%, the voltage supplied never falls below 96% the maximum value

53
Q

high-frequency power generators have ___ voltage ripple

A

1%, they have greater radiation quality and quantity

54
Q

*less voltage ripple results in:

A

greater radiation quality and quantity

55
Q

x-rays are performed with:

A

3 phase power

56
Q

fluoroscopy is performed with:

A

single-phase power

57
Q

transformers and high-voltage generators power is measured in ___

A

kilo watts (kW)

58
Q

high-voltage generators provide power to the x-ray tube in 3 ways:

A

single-phase power, 3 phase power & high-frequency power

59
Q

X-ray systems usually operate on voltages of ______ and currents of ______

A

25-150kVp, 100-1200mA

60
Q

when using the fluoro table for fluoro not for x-ray:

A

move the bucky to the foot of the table

61
Q

3 phase generators are found:

A

on the wall

62
Q

photodiodes are:

A

below the IR, shuts off based on density

63
Q

ionization chambers are:

A

above the IR

64
Q

the back up timer is always:

A

1.5 times longer than the needed exposure time

65
Q

electrons travel from ____ to ____ in the tube

A

cathode to anode

66
Q

peak x ____ = average voltage

A

peak x .707 = average voltage (keV)

67
Q

average x ____ = peak voltage

A

average x 1.41 = peak voltage (kVp)

68
Q

the autotransformer is found:

A

in the control console

69
Q

the control console is aka:

A

primary circuit

70
Q

high-voltage section is aka:

A

secondary circuit

71
Q

going from the primary to the secondary circuit there is a ____ in voltage because there is a _____ in current

A

step down, step up

Physics (13 decks)

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