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Imaging Maintenance and Equipment > M Part I > Flashcards

M Part I Flashcards

1
Q

Three Principles of X-ray Imaging System

A
  1. X-ray Tube
  2. Operating Console
  3. High Voltage Generator
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2
Q

It is attached to an overhead
Movable assembly
Location: examination room

A

Radiographic X-ray Tube

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3
Q

Localized under examination table

A

Fluoroscopic X-ray Tube

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4
Q

It must be transparent to x-rays as much as possible

A

Examination Table

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5
Q

Composition of examination table
Strong and absorbs a little bit of radiation

A

Carbon fiber

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6
Q

Fluoroscopic table degree of tilt
[..] to the foot side
[..] to the head side

A

90 degrees
30 degrees

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7
Q

It is housed in an equipment cabinet positioned against the wall
It is always close to the x-ray tube

A

High voltage generator

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8
Q

Material familiar to the radiographic table
Used to control the X-ray tube current and voltage applied to x-ray tube
Provides control of line compensation
KVp, mA, exposure time

A

Operating Console

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9
Q

Number of x-ray
Intensity of the x-ray beams
Units: mR/mAs

A

Radiation quantity

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10
Q

Penetrability of the x-ray beam
Expressed in kilovolt peak (kvp)

A

Radiation quality

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11
Q

Inside operating console
Measures the voltage provided to the x-ray imaging system
Ph - 120 V
US - 110 V

A

Line Compensator

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12
Q

Consists of only one winding of wire

A

Autotransformer

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13
Q

[function, location] Autotransformer

A

Supplies the precise voltage circuit controls the kVp
Inside operating console

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14
Q

Autotransformer require [..] to approximately increase twice the input voltage value

A

Step up voltage

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15
Q

It conducts the input power to the autotransformer

A

Primary connection

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16
Q

State the AUTOTRANSFORMER LAW/ formula

A

It states that the voltage receive & provide by the transformer is directly proportional to the no of turns
Vs/Vp = Ns/Np

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17
Q

Adjustment of Kilovoltage Peak (kVp) [adjustment controls]
represent two separate series of connections on the autotransformer.

A

Major and minor kVp

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18
Q

It determines the quality of the x-ray beam

A

-kVp

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19
Q

[part, location] It reads voltage (not kVp)

A

-kVp meter
-location: output terminals of the autotransformer

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20
Q

It allows the voltage to be monitored before an exposure

A

Prereading kVp Meter

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21
Q

It is measured in milliamperes (mA)

A

X-ray tube current

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22
Q

It determines the number of electrons emitted by the filament

A

Filament Temperature

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23
Q

It controls the filament temperature
It is measured in amperes (A)

A

Filament Current

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24
Q

Filament Current [Range]

A

3-6 A

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25
Q

It controls x-ray tube current

A

Filament Circuit

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26
Q

Explain SPACE CHARGE EFFECT

A

A phenomenon of the space charge that makes it difficult for subsequent electrons to be emitted by the filament because of electrostatic repulsion

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27
Q

Electron cloud near the filament

A

Space Charge

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28
Q

The release of electrons from a heated filament

A

Thermionic Emission

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29
Q

It is used to reduce the voltage to a value that corresponds to the selected milliampere

A

Precision Resistor

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30
Q

Design in which exposure factors are adjusted automatically to the highest mA at the shortest exposure time allowed by the high-voltage generator
Exposure behind at maximum mA and it drops as the anode heats

A

Falling Load Generator

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31
Q

Result of falling load generator

A

Minimum exposure time

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32
Q

The product of X-ray tube current (mA) and exposure time (s)
A measure of electrostatic charge

A

-mAs

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33
Q

It monitors the X-ray tube current

A

-mA Meter

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34
Q

[location, rationale] mA Meter

A

It is connected at the center of the secondary winding of the high voltage step up transformer
rationale: ensures electrical safety

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35
Q

Filament Transformer [full name]

A

Filament Heating Isolation Step-down Transformer

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36
Q

Received the voltage from the mA selector switch
Provides the current to heat the filament

A

Filament Transformer

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37
Q

Filament transformer step down the voltage to approximately [..]

A

12 V

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38
Q

Primary Windings
[material]
Current: [..]
Voltage: [..]

A

Thin copper
0.5-1 A
150 V

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39
Q

Secondary Windings
[material]
Current: [..]
Voltage: [..]

A

Thick
5-8 A
12 V

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40
Q

It terminates an exposure after a prescribed time (6s)

A

Guard Timer

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41
Q

It consists of an electronic device
-make and breaks the high voltage across the x-ray tube
-always done on the primary side

A

Time Circuit

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42
Q

Time circuit [rationale]

A

Lower voltage

43
Q

Four types of Timing Circuits

A
  1. Synchronous Timer
  2. Electronic Timer
  3. MAs Timer
  4. Automatic Exposure Control
44
Q

A precision device assigned to friends a shaft at precisely 60 revolution per second

A

Synchronous Timer

45
Q

Disadv of synchronous timer

A

It cannot be used for serial exposures

46
Q

Most sophisticated, most complicated and most accurate (as small as 1 ms)

A

Electronic Timer

47
Q

[adv] Electronic Timer

A

Allows a wide range of time intervals to be selected
Used for rapid serial exposures

48
Q

Most exposure timers are [..] and are controlled by a [..]

A

Electronic
Microprocessor

49
Q

[function] mAs timer

A
  1. Monitors the product of mA and exposure time
  2. Terminates exposure when desired mAs value is attained
  3. Provides the highest safe tube current for the shortest exposure for any mAs selected
50
Q

[location] mAs timer

A

Secondary side of the high-voltage transformer

51
Q

[applications] mAs timer

A

Falling-load
Capacitor discharge imaging system

52
Q

A device that measures the quantity of radiation that reaches the image receptor
It automatically terminates the exposure when the image receptor has received the required radiation intensity

A

Automatic Exposure Control (AEC)

53
Q

It is used to check timer accurately (as short as 1 ms)

A

Solid-State Detectors

54
Q

It increases the output voltage from the autotransformer to the kVp necessary for x-ray production

A

High Voltage Generator

55
Q

Three Primary Parts of a High Voltage Generator

A
  1. High Voltage Transformer
  2. Filament
  3. Rectifiers
56
Q

Explain relationship of primary and secondary: voltage, current, windings [high voltage transformer - step-up transformer]

A

Secondary Voltage (kVp) > primary Voltage (V)
Secondary Current (mA) < primary Current (A)
Secondary Windings > primary Windings

57
Q

Voltage waveform: [..]

A

Sinusoidal

58
Q

[..] only difference in the primary and secondary waveform

A

Amplitude

59
Q

The ratio of the no of secondary windings to the no of primary windings

A

Turns Ratio

60
Q

Turns Ratio relationship with voltage and current

A

Directly proportional to the voltage
Inversely proportional to the current

61
Q

It ensures that electrons flow from cathode to anode only

A

Voltage Rectifiation

62
Q

The process of converting alternating current flow in only one direction

A

Rectification

63
Q

An electronic device that contains two electrodes

A

Diode

64
Q

A vacuum tube (original rectifiers)
Replaced by solid-state rectifier

A

Valve tube

65
Q

Composition of valve tube

A

Silicon

66
Q

Lies between insulators and conductors

A

Semiconductor

67
Q

Two types of semiconductor

A

P-type and n-type

68
Q

Have loosely bound electrons (free to move)

A

P-type Semiconductor

69
Q

[p-type] Spaces with no electrons
As mobile as electrons

A

Holes

70
Q

N-type material placed in contact with p-type crystal
It conducts electricity in only one direction

A

Solid-State p-n junction

71
Q

Rectifier of solid-state p-n junction

A

Solid-state diode

72
Q

[..] used when medical imaging systems are described

A

Electron Flow

73
Q

The voltage is not allowed to swing negatively during the negative half of its cycle

A

Half-wave Rectification

74
Q

Half-Wave Rectifification [Diodes, Pulses]

A

0, 1 or 2
60 pulses/second

75
Q

Half-Wave Rectification [disadv]

A

It wastes half of the supply of power
It requires twice the exposure time

76
Q

The negative half-cycle corresponding to the inverse voltage is reverse

A

Full-wave Rectification

77
Q

Full-wave rectification [diodes, pulses]

A

4
120 pulses/sec

78
Q

Full-wave rectification [adv]

A

Exposure time reduced

79
Q

It results in a pulsating x-ray beam

A

Single-phase power

80
Q

Single-Phase Power [disadv]

A

X-ray produced has a value near zero

81
Q

The voltage impressed across the X-ray tube is nearly constant

A

Three-Phase Power

82
Q

Three-Phase Power [pulses]

A

6 pulses/ 1 /60 sec

83
Q

Three-Phase Power [adv, disadv]

A

Adv. voltage never drops to zero during exposure
Disadv. It’s size and cost

84
Q

Starting an exposure time

A

Initiation Time

85
Q

Ending an exposure

A

Extinction Time

86
Q

It produces a nearly constant potential voltage waveform
It uses inverter circuits

A

High Frequency Generator

87
Q

High Frequency Generator [adv]

A
  1. Much smaller & less costly & more efficient
  2. Improves image quality at lower patient radiation dose
88
Q

A high speed switchers or choppers that convert DC into a series of square pulses

A

Inverter Circuit

89
Q

T/F FULL-WAVE RECTIFICATION OR HIGH FREQUENCY VOLTAGE GENERATOR IS USED IN ALMOST ALL STATIONARY X-RAY

A

TRUE

90
Q

Tube voltage falls during exposure
Approx. 1 kV/mAs

A

Capacitor Discharge Voltage

91
Q

An automatic lead beam stopper
It stops continuous x-ray emission of capacitor bank
It is designed to be turned on and off very rapidly

A

Grid-Controlled X-ray Tube

92
Q

Grid-Controlled X-ray Tube [applications]

A

Portable capacitor discharge imaging systems
Digital subtraction angiography
Digital radiography
Cineradiography

93
Q

Refers to an element in the tube that acts as a switch

A

Grid

94
Q

Less voltage ripple means

A
  1. Greater radiation quantity
  2. High efficiency f x-ray production
  3. Greater radiation quality because of fewer electrons that pass from cathode to anode
95
Q

Characteristics of High Frequency
Frequency range : <1 kHz
[inverter features]

A

Thyristors

96
Q

Characteristics of High Frequency
Frequency range : 1-10 kHz
[inverter features]

A

Large silicon-controlled rectifier

97
Q

Characteristics of High Frequency
Frequency range : 10-100 kHz
[inverter features]

A

Power field effect transistors

98
Q

Means of characterizing voltage waveforms

A

Voltage Ripple

99
Q

Waveform
Single Phase
Half-Wave [ripple, voltage]
Full-Wave [ripple, voltage]

A

Ripple: 100%
Voltage: Varies from zero to maximum

100
Q

Waveform
Three Phase
6-pulse [ripple, voltage]
12-pulse [ripple, voltage]

A

Ripple: 14%
4%
Voltage: never falls below 86% max value
Never falls below 96% max value

101
Q

Waveform
High frequency
[ripple, voltage]

A

<1%
Never falls below 99% of max value

102
Q

Incentivizes the transformers and high-voltage generators

A

Power Rating (kW)

103
Q

Power Rating
Three-phase & high frequency [formula]

A

(MA x kVp)/1000

104
Q

Power Rating
For single-phase [formula]

A

(O.7)(mA x kVp/1000)

Imaging Maintenance and Equipment (6 decks)

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