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Radiographic Technique I > Midterm I > Flashcards

Midterm I Flashcards

0
Q

Roentgen noticed a glow from a barium platinocyanide plate while working with a __________ tube.

A

Crookes

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1
Q

Who discovered x-rays in 1895?

A

Wilhelm C. Roentgen

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2
Q

T or F: The barium plate continued to glow when surrounded by an opaque black paper

A

True

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3
Q

Roentgen “accidentally” discovered________effect.

A

Photographic

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4
Q

Roentgen noticed that the Crookes tube emitted an energy that is not________ but instead is _________.

A

Light; X-Rays

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5
Q

T or F: Roentgen ID’d all characteristics of x-rays including biological effect.

A

False, all but the biological effects

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6
Q

Thomas Edison discovered ________ and experimented with over 1800 flourescent matierals for use in x-ray imaging.

A

Flouroscope

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7
Q

George Eastman developed photographic plates and invented _______ for photography and radiography.

A

Film

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8
Q

Who developed the x-ray grid?

A

Bucky

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9
Q

Law of Conservation of Energy -Newton is:

A

Energy can be neither created nor destroyed, but it can change form.

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10
Q

What kind of wave radiation are energies that change the field they pass through?

A

Electromagnetic (EM) Wave Radiation

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11
Q

Name of the form of a repeating wave pattern that field changes occur?

A

Sine Wave (sinusoidal form)

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12
Q

Visible light and X-rays are what kind of energy?

A

Electromagnetic Energy

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13
Q

_________Radiation can remove an electron from it’s orbit, has a wavelength < or = 1nm, and x-rays are a form.

A

Ionizing

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14
Q

What is a particle model used to depict the nature of EM energy?

A

Quantum Theory

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15
Q

What is the smallest unit of EM energy?

A

Photon

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16
Q

What is Quanta?

A

groups or “bundles” of photons (singular is quantum)

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17
Q

What’s the smallest unit (“particle”) of a quantum?

A

Photon

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18
Q

How is an x-ray photon visualized?

A
  • 2 perpendicular sine waves

- traveling in a straight line & at speed of light

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19
Q

What is a form of energy associated with many naturally occurring phenomena, such as EM radiation, and has a recurring wave form?

A

Sine waves

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20
Q

Sine wave characteristics?

A

Amplitude, Wavelength, Frequency, Velocity

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21
Q

Distance from crest to valley is?

A

Amplitude

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22
Q

Crest to crest distance of a sine wave?

A

Wavelength

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23
Q

Number of crests (or valleys) that pass a fixed point per unit time?

A

Frequency

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24
Q

Wavelength x Frequency = ?

A

Velocity (EM velocity = 3x10^10 cm/sec)

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25
Q

Do sine wave with shorter wavelengths have more or less energy?

A

More energy (shorter wavelengths = higher frequency)

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26
Q

Do x-rays increase penetration with a shorter or longer wavelength?

A

Shorter

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27
Q

Characteristics of x-rays:

A

*travel in straight line at speed of light
*diverge into space until absorbed
*cause types of crystals to flouresce
*photographic effect
*human senses can’t detect
*mass and density of matter create differential penetration of x-rays
*lens cannot refract
*produce biological effects
*

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28
Q

Primary Radiation

A

x-ray beam that leaves the tube and is unattenuated (except by air); direction and location are predictable and controllable

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29
Q

Secondary/Scatter Radiation

A

Radiation created/scattered by interaction with matter and primary x-ray beam, travels in all directions, difficult to control, Primary beam energy > secondary beam energy.

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30
Q

Radiation that creates a pattern of differential absorption remaining from primary beam after it’s been attenuated by matter and creates a film image?

A

Remnant Radiation

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31
Q

Electricity: Direct current?

A

Constant power source and the current from from neg (-) to pos (+).

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32
Q

Electricity: alternating current?

A

power source alternates between positive and negative at regular intervals.

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33
Q

What is the difference in electrical potential (polarity) between 2 locations in a circuit that is measured in Volts (V), Kilovolts (kV), Kiolovolts peak (kVp)?

A

Electromotive Force (EMF), causing electric charges to flow thru the circuit

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34
Q

Describe Kilovolts

A

Voltage measured at the peak of the electrical cycle in an X-ray tube cirucuit

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35
Q

Current is the flow of electrical charges in the circuit. What units is used to measure the current?

A
  • Coulombs
  • Amperes (A or amp)
  • Milliamperes (mA): 1mA = 0.001A
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36
Q

What represents the total quantity of electrical charges

A

Coulombs

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37
Q

What represents the rate of flow of electrical charges?

A

Amperes (coulombs/second)

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38
Q

What is the Electrical supply to:

  • Household
  • X-ray tube circuit
A

Household: 120V or 30 amps

X-ray tube circuit: 120,000V or 0.3 amps; 120 kVp or 300 mA

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39
Q

4 requirements for the production of X-rays:

A
  1. Vacuum
  2. Source of electrons
  3. Target for the electrons
  4. High potential difference b/t source and target
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40
Q

Electron source for x-ray production is:

A

Tungsten filament, heated by electric current

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41
Q

Thermionic Emission is:

A

Heated tungsten -> electrons in tungsten atom orbits spin faster -> electrons move farther from nucleus -> electrons are flung out of atom -> electrons form “electron cloud” or space charge -> charge creates electron source for X-Ray

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42
Q

Tungsten filament’s space charge move to the ________ target, forming an __________.

A

Tungsten; “electron stream”

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43
Q

How is the Tungsten target positioned?

A

Slanted and located at the opposite end of the tube from the tungsten filament.

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44
Q

The positive end of the tube is called the _________ and the negative end of the tube is the _________.

A

Anode; Cathode

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45
Q

The anode is associated with the ________ and the cathode is associated with the __________.

A

Target; Filament

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46
Q

When the electrons strike the Tungsten target how much energy is converted to heat vs. x-rays?

A

99 +% into heat AND a tiny amount into X-rays.

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47
Q

The fast-moving electrons heading at the target has ________ energy from that convert to heat and x-ray when stopped by target.

A

Kinetic

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48
Q

The majority of x-ray beam consists of _________ ; which is a result of the sudden halt of electron stream at target, as kinetic energy converts to other forms of energy.

A

Bremsstrahlung (braking rays)

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49
Q

Characteristic Radiation is formed where?

A

Within the Target Atom as a result of interaction with electron stream.

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50
Q

When an orbital electron moves from 1 energy level (shell) to another, the difference in binding energy of the 2 shells is emitted as an x-ray photon called _________.

A

Characteristic Radiation

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51
Q

Why is radiation coined Characteristic Radiation?

A

Because the x-ray photon always has the same wavelength and is “characteristic” of the target element.
The difference in binding energy b/t the 2 shells is always the same

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52
Q

Purpose of X-ray Tube Housing?

A
  • protects tube
  • absorbs radiation
  • provides mounting for tube attachments (ie. collimator)
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53
Q

Requirements of x-ray production

A
  1. Vaccuum
  2. Free electrons
  3. Target
  4. High voltage (high potential diff b/t source and target)
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54
Q

2 types of interactions form the primary beam:

A
  • Bremsstrahlung (heterogenous)

* Characteristic (unique wavelength specific to target material)

55
Q

What would happen without a Focusing Cup at the Cathode?

A

Electron stream would spread beyond the target area.

56
Q

Negatively charged focusing cup _______ electrons, focusing them on small ________ ______.

A

Repels; target area (“focal spot”)

57
Q

Most modern general purpose tubes are “_____ ______.”

A

Dual Focus

58
Q

Dual Focus tubes have 6 important components?

A
  • 2 x filaments
  • 2 x focusing cups
  • 2 x concentric focal spots
59
Q

Filaments and focal spots are selected in association with mA settings and mA circuits. What is an example?

A

25-150 mA use small filament and small focal spot.
vs.
200 mA and above use large filament and large focal spot.

60
Q

Composition of Anode:

A
  • Tungsten target imbedded in molybdenum disc

* Mass of copper (conducts heat from target)

61
Q

2 characteristics of Anode?

A
  • Angulation: target face is beveled at 10-20 degree slant

* 2 concentric focal spots: 1 large & 1 small

62
Q

Actual focal spot vs. Effective focal spot

A

Actual = measurement of focal spot ON target surface

Effective = measurement of vertical projection

63
Q

Tubes that have 2 concentric focal spots, 1 large and 1 small, are called?

A

Dual Focus tubes

64
Q

Actual Focal spot size affects tube _____ ______ and ______ size is Better.

A

Heat Capacity; BIGGER

65
Q

Effective Focal Spot size affects ______ ______ and ______ size is better.

A

Image sharpness; Smaller

66
Q

Line Focus Principle:

A
  • size of Effective focal spot determines image sharpness
  • target Angle determine relative size of effective focal spot
  • Steeper angle of target creates a greater difference b/t actual and effective focal spot sizes.
67
Q

Anode Angulation determines maximum ______ ______ and the steeper the angle results in a ________ effective focal spot.

A

Field Size; Smaller

68
Q

Steeper the Target Angle ________ differential between Actual and Effective focal spots AND results in a ________ Effective Focal Spot.

A

Increases; Smaller

69
Q

What anode angulation (degree) is needed to cover a 14” x17” distance from the source?

A

12 degrees

70
Q

Where are x-rays formed?

a. within Target Material
b. within Cathode Filament
c. Between a and b

A

a. Target Material

71
Q

T or F: Anode Heel Effect is caused by an uneven absorption of the primary beam at the sloping target.

A

True - and results in variation in radiation intensity

72
Q

The “heel” of the sloping target absorbs the most of the primary beam causing the radiation at the “heel” to be _________ intense.

A

Less

73
Q

Radiation intensity is _________ toward the cathode end of the Targets slope.

A

Greater

74
Q

The Anode Heel Effect is important in AP Thoracic spine. Why?

A

The greatest X-ray intensity needs to go through the thickest part of the body, which we know is at the cathode end of the field.

75
Q

Anode Heel Effect: The thinner part (head) is placed at ______ side (“cathode facing”) and the thicker (chest) is placed at _______ side.

A

Anode; Cathode

76
Q

To control rate of flow of electrons across the tube the ______units are set to heat up the filament, therefore controlling rate of ________production.

A

mA; X-Ray (Radiation exposure is proportional to mA)

77
Q

Exposure Time is controlled by a _______ in x-ray circuit, therefore controlling duration of exposure and _______of x-rays produced.

A

Timer; Quantity (Radiation exposure is proportional to exposure time)

78
Q

mA x ? = mAs (total quantity of electricity involved in exposure)

A

time

79
Q

What is controlled to increase speed of electrons and kinetic energy and shorter wavelength?

A

Kilovoltage (kVp); control power source

80
Q

What does 99+% of x-ray tube energy convert into?

A

Heat

81
Q

What are 4 effects of overheating the tube?

A
  1. Anode degradation -> unsharp image
  2. Extra gas from hot components -> erratic exposures
  3. Heavy exposure -> crack anode
  4. Break tubes, compromises tube/oil seal -> destroys tube
82
Q

What features of the tube design are helping to minimize overheating tube?

A
  1. Rotating anode on circumferential focal spot
  2. Material used (tungsten, molybdenum, & graphite)
  3. Copper conducts heat away from Tungsten
  4. Control Circuits (mA, kVp, time)
83
Q

Common Sense when taking x-ray, pertaining to the tube?

A
  1. Tube needs 10-30 seconds to cool after each exposure
  2. If tube is hot to touch then don’t use until tube has cooled
  3. Allow cold tube to warm-up
  4. Safe large exposures: use tube rating chart to determine
  5. Don’t hold Rotor Switch down for long time
  6. Don’t use tube when rotor bearings are heard
84
Q

What are 4 points unique about Tube Rating Charts?

A
  1. Indicate maximum safe settings
  2. Specific chart to each tube design
  3. Use when creating a technique chart
  4. Check when using Large Exposure
85
Q

Estimate the tube load with the info below:

exposure = 400 mA, 1/10 sec, 85 kVp
Max. safe exposure = 400 mA, 3/10 sec, 85 kVp

A

mA x time = mAs
Exposure: mAs = 40
Max. safe exp: mAs = 120

Therefore Tube Load: 40/120 = 33 1/3%

86
Q

Why is this equation used:

mA x Time x kVp x 1.45 = HU

A

To make a cooling chart when evaluating a series of exposures with little time in between

87
Q

The process of causing alternating current flow in 1 direction only?

A

Rectification (“To Make Right”)

88
Q

When the nature of the X-ray tube prevents current from flowing from anode to cathode during 1/2 the electrical cycle it’s called?

A

Self-Rectification

89
Q

When diodes placed within the circuit to “back-up” self-rectification this is called?

A

Half-wave Rectification (same prevention of back-flow of current)

90
Q

When 4 diodes in a circuit are used to redirect current during the whole cycle allowing x-ray production during the entire electrical cycle it’s called?

A

Full-Wave Rectification

91
Q

Full-Wave Rectification decreases exposure time to ________ that required by self- or half-rectified x-ray machine.

A

Half

92
Q

What are some benefits to a Three-phase and High Frequency Generation?

A
  1. more constant power supply and efficient voltage source
  2. the rectified current is a ripple with no real low points
  3. produces near-constant voltage waveform
93
Q

What accessory on the tube controls the Radiation Field?

A

Collimator

94
Q

What are 3 types of Collimators?

A
  1. Manual - adjust to each field dimension
  2. Automatic - Sensors in film tray determine film size and adjust collimator.
  3. Semi-automatic - manually adjusted, but exposure is locked out unless field size is smaller than film size
95
Q

Legal Requirements for Collimators?

A
  1. Rectangular collimator with independent adjustment of each dimension
  2. Must indicate field dimensions
  3. Must have light that delineates field accurately within 2% of SID & indicates center of field
  4. Field cannot be larger than film (only collimate clinical interest)
96
Q

What wavelength gets filtered out of the primary beam and why?

A
  • Long wavelength (attenuates low energy photons)

* It doesn’t have sufficient energy to penetrate the patient, lowers radiation does significantly

97
Q

Units filtration is measured?

A

millimeters of aluminum (mm. Al equiv.)

98
Q

Types of accumulated Filtration of the primary beam(p. 13)?

A
  • Inherent - by glass of the tube envelope; 0.5 mm. Al equiv.
  • Added - Aluminum plates (1.0 mm. Al) & Collimator parts (mirror, face plate; 1.0 mm. Al)
99
Q

All machines capable of operating above 70 kVp are required to have at least ____ mm Al equiv. total filtration permanently installed.

A

2.5

100
Q

Filtration changes:

a. dose of radiation
b. exposure requirements
c. image quality

A

a. - decreases dose to ~1/4 the unfiltered dose

101
Q

Which of the following will make the radiograph darker:

a. Increased mA
b. Increased exposure time
c. Both a & b
d. neither

A

c.

102
Q

Exposure is directly proportional to milliamperage (mA) and Quantity of exposure is directly proportional to __________.

A

Time

103
Q

Higher mA increases heat load of tube – greater total load is possible with _______mA settings.

A

Lower

104
Q

Unit used to indicate the total quantity of x-rays in an exposure?

A

Milliampere-seconds (mAs)

105
Q

What is the primary controller of radiographic density:

a. mA
b. time
c. mAs

A

c. mAs

106
Q

What units of voltage is the primary controller of the speed of electrons from cathode to target?

A

Kilovoltage (kVp)

107
Q

kVp is not directly proportional to exposure, but kVp does directly affect radiographic _________.

A

Contrast

108
Q

High kVp produces a _______contrast image and Low kVp produces a ________contrast image.

A

Low; High

109
Q

kVp is the primary controller of radiographic __________.

A

Contrast

110
Q

Two functions of kVp are?

A
  • Penetration of beam

* Radiographic scale of contrast

111
Q

The distance between the tube target and imaging receptor?

A

Source-Image Distance (SID)

112
Q

The Inverse Square Law says the intensity of the radiation is ______ proportional to the square of the _______. Therefore, when SID 80 inches (vs. 40 inches) the field size is 4X as large, and the x-ray intensity is 4X less.

A

inversely; distance

113
Q

I1 D2^2
— = —
I2 D1^2
What’s I2 at 80” if the intensity is 1 at 40”

A

Intensity of I2 = 1/4

114
Q

Since distance (SID) affects radiation intensity and mAs affects radiation intensity, then an increase in SID may need to _______ mAs to compensate for distance.

A

increase

115
Q

mAs Distance rule = constant exposure is maintained when changing the distance by varying the mAs in direct proportion to the _______ of the distance.

A

SQUARE
mAs1 D1^2
—— = ——
mAs2 D2^2

116
Q

mAs1 D1^2
—— = ——
mAs2 D2^2

D2^2 =72” ; D1^2=40 ; mAs1=10 ; mAs2 = ?

A

mAs2 = 32.4

117
Q

Radiographic Density is affects the visibility (over-all blackness/density) of detail of exposure, which is directly controlled by________ and indirectly controlled by _______ & _______.

A

mAs; kVp & SID

118
Q

What is the difference in radiographic density between adjacent portions of the image?

A

Contrast

119
Q

What is the Contrast primarily controlled by?

A

kilovoltage (kVp)

120
Q

High kVp creates a _________contrast and Low kVp creates _______contrast.

A

low (many shades of gray) ; high (few shades of gray more black/white)

121
Q

Films looking for bone problems try to use ________contrast, films looking at soft tissues (lung fields) try to use ________contrast.

A

High; Low

122
Q

What is the name of a step-wedge made of aluminum that estimates the # of shades of gray in film?

A

Penetrometer

123
Q

The desired scale of contrast is influenced by the range of differences in the intensity of the x-ray beam exiting the body, which is known as the _______ ________.

A

Subject contrast

124
Q

The Abdomen has a _______subject contrast due to the similar tissue densities of the tissue, and needs a _____kVp. The Chest has________subject contrast due to the wide varying tissue densities, and needs a _______kVp.

A

low and high; high and low

125
Q

General, unwanted exposure to the film is referred to as_________ and ________contrast (hint: longer scale of contrast).

A

Fog; decrease

126
Q

What is the difference between the actual subject and it the radiographic image?

A

Distortion

127
Q

Magnification caused by any combo of short SID &/or large OID is?

A

Size distortion

128
Q

What is the unequal magnification of image due to the part being imaged not being parallel to the image or the beam not being perpendicular to the image (or both)?

A

Shape distortion (i.e. scaphoid image)

129
Q

When OID is larger therefore ________Magnification and Distortion.

A

Increases

130
Q

Decrease the SID _______Magnification and Distortion. To correct for a large OID _________SID.

A

Increase; Decrease

131
Q

2 things that cause shape distortion?

A
  1. object not parallel/aligned to image receptor (IR)

2. X-ray tube and IR are not aligned

132
Q

When trying to maximize the detail/sharpness of the radiograph what are 3 important factors?

A
  1. Focal Spot Size (FSS)
  2. Object-image distance (OID)
  3. Source-image distance (SID)
133
Q

When the FSS is reduced to the size of a point does it increase or decrease penumbra? Why?

A

Decreases, because the x-ray beam is produced in less areas of the anode target decreasing the divergence of photons.

134
Q

What changes (increase or decrease) in OID and SID will decrease the penumbra?

A

decrease OID and increase SID

135
Q

What does P.A.C.S. stand for?

A

Picture Archiving and Communication System

136
Q

What is hardware and software for managing digital images with computed and/or digital radiography?

A

PACS

Radiographic Technique I (2 decks)

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