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C1 > ELECTROMAGNETISM & XRAY IMAGING SYSTEM > Flashcards

ELECTROMAGNETISM & XRAY IMAGING SYSTEM Flashcards

1
Q

What is the primary function of an x-ray imaging system?

A

To convert electric energy into electromagnetic energy.

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2
Q

The study of stationary electric charges.

A

electrostatics

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3
Q

What are the smallest units of electric charge?

A

Electrons and protons.

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4
Q

What is the SI unit of electric charge?

A

Coulomb (C).

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5
Q

How many electron charges are in 1 Coulomb?

A

6x10^18

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6
Q

What does it mean for an object to be electrified?

A

It has too few or too many electrons.

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7
Q

How can electrification be created?

A

By contact, friction, or induction.

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8
Q

What is electric ground?

A

An object that serves as a reservoir for stray electric charges.

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9
Q

What is Coulomb’s Law?

A

Electrostatic force is directly proportional to the product of charges and inversely proportional to the square of the distance between them.

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10
Q

What is the SI unit of electric potential?

A

Volt (V).

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11
Q

What is 1 Volt equivalent to?

A

1 Joule/Coulomb.

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12
Q

What is electrodynamics?

A

The study of electric charges in motion.

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13
Q

What is a conductor?

A

A material through which electrons flow easily.

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14
Q

What is an insulator?

A

A material that does not allow electron flow.

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15
Q

What is a semiconductor?

A

A material that behaves as both a conductor and insulator under different conditions.

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16
Q

What is a superconductor?

A

A material that allows electron flow without resistance.

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17
Q

What does Ohm’s Law state?

A

Voltage across a circuit is equal to current times resistance:
V=IR.

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18
Q

What is the SI unit of resistance?

A

Ohm (Ω).

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19
Q

What are the two types of electric circuits?

A

Series and parallel circuits.

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20
Q

How is total resistance calculated in a series circuit?

A

RT = R1+R2+R3

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21
Q

How is total resistance calculated in a parallel circuit?

A

1/RT = 1/R1+1/R2+1/R3

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22
Q

Inhibits electron flow.

A

RESTRCITOR

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23
Q

What does a battery do in a circuit?

A

Provides electric potential.

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24
Q

Momentarily stores electric charge

A

Capacitor

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25
Q

What is direct current (DC)?

A

Electrons flowing in one direction.

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26
Q

What is alternating current (AC)?

A

Electrons flowing alternately in opposite directions.

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27
Q

What is magnetite?

A

An oxide of iron, also called lodestone.

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28
Q

What creates a magnetic field?

A

Any charged particle in motion.

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29
Q

A magnet with two poles (north and south).

A

dipolar magnet

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30
Q

An accumulation of aligned atomic magnets.

A

magnetic domain

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31
Q

What are the four magnetic states of matter?

A

Nonmagnetic, diamagnetic, paramagnetic, and ferromagnetic.

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32
Q

What is magnetic permeability?

A

The ability of a material to attract magnetic field lines.

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33
Q

What is magnetic susceptibility?

A

The degree to which a material can be magnetized.

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34
Q

What is the SI unit of magnetic field strength?

A

tesla

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35
Q

Developed the voltaic pile, a precursor to the modern battery.

A

alessandro volta

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36
Q

A coil of wire that creates a magnetic field when carrying current.

A

solenoid

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37
Q

What is Faraday’s Law?

A

The magnitude of an induced current depends on magnetic field strength, velocity, angle, and conductor turns.

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38
Q

Converts electric energy into mechanical motion.

A

electric motor

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39
Q

Converts mechanical motion into electric energy.

A

electric generator

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40
Q

What is a transformer?

A

A device that changes the intensity of alternating voltage and current.

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41
Q

What is a step-up transformer?

A

Increases voltage while decreasing current.

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42
Q

What is a step-down transformer?

A

Decreases voltage while increasing current.

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43
Q

What is a high-voltage generator?

A

Increases output voltage for x-ray production.

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44
Q

What does a rectifier do?

A

Converts AC to DC.

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45
Q

Voltage flows in only one direction, using half the AC cycle.

A

half-wave rectification

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46
Q

Converts the entire AC cycle into usable current.

A

full-wave rectification

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47
Q

What is the advantage of a high-frequency generator?

A

Produces a nearly constant voltage, improving image quality and reducing patient dose.

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48
Q

What is the purpose of a capacitor discharge generator?

A

Maintains x-ray tube voltage during exposure.

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49
Q

Acts as a rapid switch to stop x-ray emission.

A

grid-controlled x-ray tube

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50
Q

A measure of variation in voltage during x-ray production.

A

voltage ripple

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51
Q

What is the voltage ripple percentage for a single-phase system?

A

100%

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52
Q

What is the voltage ripple percentage for a high-frequency system?

A

Less than 1%.

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53
Q

What are the three main sections of the x-ray imaging system?

A

X-ray tube, operating console, and high-voltage generator.

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54
Q

What is the composition of the examination table?

A

Carbon fiber, for strength and minimal x-ray absorption.

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55
Q

What does the operating console control?

A

X-ray tube current, voltage, line compensation, and exposure time.

56
Q

What is radiation quantity?

A

The number or intensity of x-rays in the beam, measured in mR or mR/mAs.

57
Q

What is radiation quality?

A

The penetrability of the x-ray beam, expressed in kVp or HVL.

58
Q

What is the purpose of the autotransformer?

A

Supplies a precise voltage to the filament and high-voltage circuits.

59
Q

Vp meter measure?

A

Voltage, not directly kVp.

60
Q

Controlling x-ray tube current by heating the filament.

A

filament circuit

61
Q

What is thermionic emission?

A

The release of electrons from a heated filament.

62
Q

What is space charge?

A

A cloud of electrons near the filament.

63
Q

Difficulty in emitting additional electrons due to electrostatic repulsion.

A

space charge effect

64
Q

Automatically adjusts to the highest mA for the shortest exposure time.

A

falling load generator

65
Q

Steps down voltage and provides current to heat the filament.

A

filament transformer

66
Q

What is the purpose of the guard timer?

A

Terminates an exposure after 6 seconds.

67
Q

What is the role of the timer circuit?

A

Makes and breaks the high voltage across the x-ray tube.

68
Q

What are the four types of timing circuits?

A

Synchronous timer, electronic timer, mAs timer, and automatic exposure control (AEC).

69
Q

A device that drives a shaft at precisely 60 revolutions per second.

A

synchronous timer

70
Q

What is an electronic timer?

A

The most accurate and sophisticated timer, allowing intervals as small as 1 ms.

71
Q

Monitors mA and exposure time, terminating exposure when the desired mAs is reached.

A

mAs timer

72
Q

Automatically terminates exposure when the image receptor receives sufficient radiation.

A

automatic exposure control (AEC)

73
Q

What does a solid-state detector measure?

A

Timer accuracy as short as 1 ms.

74
Q

What is the turns ratio in a high-voltage transformer?

A

Ratio of secondary windings to primary windings, e.g., 500:1.

75
Q

Ensures current flows in one direction, converting AC to DC.

A

rectification

76
Q

What is a solid-state rectifier made of?

A

silicon

77
Q

Contact point between p-type and n-type semiconductors, allowing current to flow in one direction.

A

p-n junction

78
Q

What is the purpose of inverter circuits in high-frequency generators?

A

Converts DC into square pulses.

79
Q

What is the typical frequency range of high-frequency generators?

A

10–100 kHz.

80
Q

What is a single-phase power disadvantage?

A

Produces x-rays with low energy due to high voltage ripple.

81
Q

What is the advantage of three-phase power?

A

Produces nearly constant voltage across the x-ray tube.

82
Q

What is a shell-type transformer?

A

A transformer with primary and secondary windings wrapped around a central core for greater efficiency.

83
Q

A transformer with one winding used to control kVp.

A

autotransformer

84
Q

What is line compensation?

A

Adjustment of incoming voltage to a consistent level.

85
Q

Increases voltage from the autotransformer to kVp levels needed for x-ray production.

A

high-voltage generator

86
Q

What is the role of a capacitor in the x-ray imaging system?

A

Stores electric charge temporarily.

87
Q

What are the components of a high-voltage generator?

A

High-voltage transformer, filament transformer, and rectifiers.

88
Q

Acts as a variable resistor to control current.

A

rheostat

89
Q

What is the voltage range for diagnostic x-rays?

A

25–150 kVp.

90
Q

What is the purpose of a diode?

A

Allows current to flow in only one direction.

91
Q

What are the three main parts of the x-ray imaging system?

A

X-ray tube, operating console, and high-voltage generator.

92
Q

side of the x-ray tube where x-rays are produced.

A

anode

93
Q

side of the x-ray tube that emits electrons.

A

cathode

94
Q

What is the principle of electromagnetic induction?

A

A changing magnetic field induces an electric current.

95
Q

Retention of magnetization in materials even after the magnetic field is removed.

A

hysteresis

96
Q

A region in a material where magnetic dipoles align.

A

magnetic domain

97
Q

A material’s ability to support magnetic field formation.

A

magnetic permeability

98
Q

What are ferromagnetic materials?

A

Strongly magnetized materials like iron and cobalt.

99
Q

What are paramagnetic materials?

A

Weakly attracted materials like gadolinium.

100
Q

What are diamagnetic materials?

A

Materials weakly repelled by a magnetic field, e.g., water.

101
Q

What does a magnetic dipole create?

A

A small magnet.

102
Q

What does an electromagnet consist of?

A

A current-carrying coil of wire around an iron core.

103
Q

Powers the rotating anode of the x-ray tube.

A

induction motor

104
Q

Reduces energy loss and increases efficiency.

A

transformer core

105
Q

What is eddy current loss in transformers?

A

Energy loss due to induced currents in the core.

106
Q

A semiconductor device used in high-frequency generators.

A

thyristor

107
Q

What is the energy range for x-ray photons in diagnostic imaging?

A

30–150 keV.

108
Q

What are the two types of x-ray tubes?

A

Radiographic and fluoroscopic.

109
Q

Supports the patient and allows tilting for fluoroscopic procedures.

A

fluoroscopic table

110
Q

Switches current direction in an electric motor.

A

commutator ring

111
Q

What are the three primary regions of the x-ray spectrum?

A

Bremsstrahlung radiation, characteristic radiation, and continuous spectrum.

112
Q

What is the main purpose of the x-ray tube housing?

A

Protects against leakage radiation and supports the tube.

113
Q

What material is commonly used for x-ray tube housing?

A

Lead-lined material to reduce leakage radiation.

114
Q

What is the function of the filament in the x-ray tube?

A

Emits electrons through thermionic emission.

115
Q

What is the typical range of filament current?

A

3–6 amperes.

116
Q

Focuses the electron beam onto the target area of the anode.

A

focusing cup

117
Q

What material is commonly used as the anode target?

A

Tungsten, due to its high melting point and atomic number.

118
Q

What is the maximum tilt angle of a fluoroscopic table?

A

90 degrees to the foot side and 30 degrees to the head side.

119
Q

What is the typical rotation speed of a standard anode?

A

3,000–10,000 revolutions per minute (rpm).

120
Q

What is the purpose of oil in the x-ray tube housing?

A

Provides insulation and cooling.

121
Q

Transmits electrical energy from the generator to the x-ray tube.

A

high-voltage cable

122
Q

The x-ray beam that exits the x-ray tube and is directed at the patient.

A

primary beam

123
Q

What is the purpose of a grid in radiology?

A

Reduces scatter radiation reaching the image receptor, improving image contrast.

124
Q

What is the common grid ratio in diagnostic imaging?

A

8:1 or 12:1.

125
Q

Holds the grid and image receptor in place.

A

a bucky system

126
Q

What is the function of an image intensifier in fluoroscopy?

A

Converts x-rays into a visible light image, enhancing brightness.

127
Q

What is the output phosphor in an image intensifier?

A

Converts electrons into a visible light image.

128
Q

What is automatic brightness control (ABC) in fluoroscopy?

A

Maintains consistent image brightness by adjusting exposure factors.

129
Q

What is a photomultiplier tube used for in imaging?

A

Amplifies light signals for processing.

130
Q

What is the role of a flat-panel detector in digital imaging?

A

Captures x-ray photons and converts them into electrical signals.

131
Q

used for storing and managing digital images.

A

PACS

132
Q

a standard for storing and transmitting medical images.

A

DICOM

133
Q

What is the difference between CR and DR systems?

A

CR uses cassettes with photostimulable plates, while DR uses flat-panel detectors.

134
Q

What is beam filtration?

A

The removal of low-energy x-rays from the beam to reduce patient dose.

135
Q

What is the minimum total filtration required for diagnostic x-ray tubes?

A

2.5 mm aluminum equivalent for x-ray tubes operating above 70 kVp

C1 (9 decks)

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