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ARRT > Safety > Flashcards

Safety Flashcards

1
Q

4 requirements necessary for production of xrays

A
  • source of free electrons
  • acceleration of electrons
  • focusing of electrons
  • deceleration of electrons
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2
Q

Thermionic emission

A

Heating of the filament to the point that electrons boil off its surface

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3
Q

What determines the amount of current that will be sent to the filament

A

mA settings

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4
Q

Where does current come from

A

From the step down transformer to produce thermionic emission

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5
Q

Acceleration of electrons

A

High electrical potential (voltage) is applied to the cathode end of the xray tube

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6
Q

How is x-radiation produced

A

By high speed electrons bombarding target area or anode

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7
Q

What is target area made out of

A

Tungsten w/ rhenium

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8
Q

Focusing cup

A

Surrounds the filament and maintains a concentrated stream of electrons from filament to target area on anode

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9
Q

What is the focusing cup made out of

A

Molybdenum or nickel

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10
Q

What are two components of the cathode

A

Focusing cup and filament wire

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11
Q

What is the filament wire made up of

A

Tungsten w/ thorium

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12
Q

Deceleration of electrons

A
  • high speed electrons will strike tungsten target on anode and will get converted to xray
  • produce heat 99%
  • 1% converted to xray
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13
Q

Atom

A

Smallest subdivision of an element that maintains all the physical and chemical properties of an element

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14
Q

What is the atomic mass of protons and neutrons

A

1

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15
Q

Atomic number (Z)

A

of protons in nucleus

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16
Q

Atomic mass (A)

A

Sum of protons and neutrons in nucleus

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17
Q

Electrons

A

Negatively charged and have no mass

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18
Q

Electrons held in their orbital shells by what

A

Electron binding energy (K shell= 69.53/70)

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19
Q

Tungsten atom Z #

A

74

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20
Q

Valence number

A
  • Number of electrons in last orbital shell (outermost max shell=8)
  • 2n^2
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21
Q

Ionization

A
  • When an energy source contains sufficient energy to remove an electron from one of the orbital shells
  • previously uncharged atom will now have an electrical charge (positive)
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22
Q

What is the Brem photon energy equal to

A
  • The amount of energy lost by the projectile electron
  • greater the direction change, greater energy loss, and brem xray photon will have more energy
  • anything before 70 is all Brems
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23
Q

Characteristic (k-char.) radiation

A

High speed electrons interact with tungsten target atom by ejecting an inner shell electron and ionizing atom

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24
Q

Process of filling the k-shell vacancy results in what

A

The emission of a characteristic xray photon

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25
Q

In k-char, energy of the xray photon is equal to what

A

Difference between the EBE of the orbital shell that contained the vacancy (k shell) and the orbital shell that filler the vacancy (70 minus L, M, N..)

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26
Q

When producing K char rad, what must the tube potential be

A

70

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27
Q

As a tech, when selecting 60 kV, how much of kV will be Brem?

A

100?

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28
Q

X-radiation if one form of what

A

Electromagnetic energy on the electromagnetic spectrum

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29
Q

Photon

A

Smallest bit of electromagnetic energy

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30
Q

Particulate radiation

A

Beta and alpha radiation- travel in particles

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31
Q

Frequency

A

Rate of rise and fall (oscillation) of the electromagnetic photon and is measured in hertz (Hz)

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32
Q

Wavelength

A

Distance between two successive peaks of an electromagnetic photon

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33
Q

Frequent and wavelength

A

Inversely related

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34
Q

Xray moves at speed of light

A

3 x 10^8 meters/sec (186,000 miles/sec)

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35
Q

Quality of beam

A

kVp, energy, penetrability, wavelength

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36
Q

Quantity of beam

A
  • mAs, rate of exposure, intensity, pt dose
  • measured in roentgen, mR, or mGy
  • xray quantity directly proportional to mAs
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37
Q

xray quantity indirectly related to what

A

Filtration and distance

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38
Q

Technical factors that affect half value layer

A

kVp and filtration

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39
Q

What is the difference between xray and gamma

A

The source of radiation

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40
Q

Inverse square law

A

Used to calculate a change in beam intensity with changes in SID

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41
Q

Direct square law

A

Determine the change in mAs required if radiographic density is to remain constant and SID is changed

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42
Q

Image forming beam

A

Remnant xray beam

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43
Q

Attenuation

A

Progressive absorption of xray beam as it passes through matter

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44
Q

If distance gets doubled or cut in half, intensity will change how much

A

By factor of 4

(Double= 4 x less) ?

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45
Q

Properties of xrays

A

1) travel in wave form
2) highly penetrating visible rays that are a form of electromagnetic radiation
3) heterogeneous (0-60) and polyenergetic
4) travel in straight lines
5) can ionize matter and release small amounts of energy upon passing through matter
6) can produce chemical and biological changes in matter through ionization and excitation of atoms and molecules
7) produce secondary and scattered radiation
8) travel at speed of light
9) no mass or electrical charge
10) high frequency and short wavelength- interact with matter on atomic and molecular level

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46
Q

Compton scatter

A
  • Partial absorption of the incident xray photon

- incident xray photon interacts with an outer shell electron of a target atom and removes the electron

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47
Q

Compton interaction can be

A
  • forward scattering: degradation of image contrast
  • side scatter: result in occupational exposure
  • backscatter: resulting in pt exposure
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48
Q

Biggest source of scatter

A

Patient

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49
Q

During fluoro, what is a techs largest source of occupational exposure

A

Compton scatter

50
Q

What is the maximum number of times an xray photon can be scattered before it loses all of its energy

A

2 times

51
Q

During fluoro, 90 degree angle, right angle, perpendicular

A

Least amount of radiation (or close to 90)

52
Q

During fluoro, 180 degree, head of foot

A

Most scatter

53
Q

Photoelectric absorption

A
  • total absorption of xray photon
  • incident xray photon interacts with an inner K shell electron and remove electron
  • all of remaining energy of incident photon is transferred to the ejected electron (photoelectron)
54
Q

What is the primary source of patient radiation exposure

A

Photoelectric interaction

55
Q

Every time an xray photon gets scattered, it will leave with how much of its original intensity

A

1/1000- 0.001

Or 0.1%

56
Q

Coherent (classical) scatter

A
  • incident xray photon interacts with a target atom and excited the atom
  • no orbital electrons and ejected, no ionization takes place
  • no energy is exchanged b/w incident photon and target atom
  • incident xray photon undergoes a change in direction with no energy loss
57
Q

Contribute to patient skin exposure or degeneration of image quality

A

Classical coherent scattering

58
Q

Absorbed dose

A

Gray (Gy) 0.01 multiplication factor
1 Gy= 100 rads
1 cGy= 1 rad

59
Q

Dose equivalent

A

Sievert (Sv) 0.01 multiplication factor

1 Sv= 100 rems or 1 cSv= 1 rem

60
Q

Quality factor of xrays, gamma rays, and beta particles

A

1

61
Q

Quality factor of protons

A

5

62
Q

Quality factor of fast neutrons

A

10

63
Q

Quality factor of alpha particles

A

20

64
Q

Exposure

A

Coulombs per kilogram of air (C/kg)

2.58 x 10^ -4

65
Q

Effective dose

A

Sv

66
Q

Air kerma

A

Gy

67
Q

Curie (Ci)

A

Measurement of radioactivity
Standard equivalent: Becquerel (Bq)
3.7 x 10^10

68
Q

Which trimester is the least resistant?

A

First

69
Q

Non-threshold dose effect relationship

A
  • any given dose of rad will yield some measurable effects

- no amount of radiation, regardless of dose, is safe

70
Q

Threshold dose effect relationship

A

Some amount of radiation is required before a measurable effect can be detected

71
Q

Law of Bergonié and tribondeau

A

Cell radio sensitivity is affected by
Mitotic activity: radio sensitivity increases with increased maturity
Maturity
Degree of specificity

72
Q

Linear energy transfer: LET

A
  • the rate of energy deposited per unit track length through an absorber
  • amount of radiation that is transferred to the body as the xray beam travels through the body
  • diagnostic xrays are considered low LET radiation
73
Q

What happens to the quality factor for a given form of radiation as LET increases

A

It will increase

74
Q

Oxygen effect

A

The ability of aerobic conditions to enhance the effectiveness of radiation

75
Q

Increasing the oxygenation of a cell does what to the cell’s sensitivity to radiation?

A

Increases it

76
Q

Oxygen enhancement ratio (OER)

A
  • numeric description of the oxygen effect

- the effectiveness of radiation in an aerobic environment is 3x greater than an anoxic environment

77
Q

Relative biologic effectiveness (RBE)

A

-ability to produce biologic damage

78
Q

Increasing the LET of radiation will result in what effect to biologic damage?

A
  • Increase in biologic damage

- LET and RBE and directly related

79
Q

What is the most radiosensitive cell in the body?

A

Lymphocytes

80
Q

Least sensitive to greatest sensitive

A

1) nerve
2) muscle
3) stem/intestinal crypt
4) lymphocytes

81
Q

Cell survival and recovery (LD 50)

A

Lethal dose to 50% of pop. over ___ number of days

82
Q

Factors influencing survival

A

LET and oxygen

83
Q

Fractionation

A
  • Equal doses of radiation that are delivered with time interval separations
  • offers cell the greatest ability to survive and recover from radiation exposure
84
Q

Protraction

A

Radiation dose that is delivered continuously but at a lower dose rate

85
Q

Radiolysis

A
  • Radiation interaction with water
  • photon-water interaction results in ionization of water (HOH+ & e-)
  • positive water molecule can split into a free radical (highly reactive and unstable substance)
86
Q

Free radicals can combine to form toxic substances such as

A

hydrogen peroxide (H2O2)

87
Q

Radiation in directly or indirectly the cause of biologic damage?

A

Indirectly
-majority of rad damage of body is caused by the indirect action of radiation interacting with water due to large amount of water in cell

88
Q

Interphase death

A
  • Apoptosis
  • cell dies without attempting to divide
  • Amount of rad to cause interphase death depends on radio sensitivity of cell
89
Q

Metaphase

A

Cell most sensitive

90
Q

Mitosis

A

Cell division

91
Q

Meiosis

A

Germ (sex) cell division

92
Q

Mitotic delay

A

Mitotic activity resumes after a short delay

Usually 10 mGy or 0.01 Gy

93
Q

Reproductive failure

A

Cell does not die as a result of radiation exposure but loses the ability to procreate
1000 to 10,000 mGy

94
Q

Somatic effects

A

Those limited to the exposed population (individual cell of body)

95
Q

Short term somatic effects

A
  • occur soon after exposure seconds, minutes, hrs, days, weeks
  • epilation, nausea, vomiting, erythema, fatigue, epistaxis
96
Q

Long term somatic effects

A
  • occur years after exposure
  • development of disease or the causes of mortality of an exposed pop are the same as unexposed pop
  • cancer (leukemia) cataractogenesis, life span shortening
97
Q

Acute (short term) exposure

A
  • large dose over short time

- more life span shortening than chronic rad exposure

98
Q

Chronic (long term) exposure

A
  • rad in small increments over long period of time (ex. occupational)
  • 1 rad (0.01 Gy or 10 mGy)= 10 days of life span shortening
99
Q

What is the most radiosensitive part of eye

A

Lens

100
Q

What are the results of opacity in the lens of the eye due to radiation exposure?

A

Cataracts

101
Q

Eye

A

Nonlinear, threshold dose (non-stochastic)

102
Q

Thyroid

A

Linear, non threshold dose (stochastic)

103
Q

Breast

A

Linear, non threshold dose (stochastic)

104
Q

Bone marrow

A

Linear, threshold dose response

105
Q

Skin

A

Threshold (non-stochastic)

106
Q

Female gonad

A
  • immature ova very radiosensitive

- mature ova not radiosensitive and can carry damaged chromosomes

107
Q

Male gonad

A
  • doses from 500-600 rads (5-6 Gy) can cause permanent sterility
  • doses of 10 rads (100 mGy) can result in genetic mutations
108
Q

Carcinogenesis

A
  • long term somatic effect of radiation
  • cancer formation long after exposure to radiation
  • where cancer may occur depends on rad dose and organ sensitivity
109
Q

Local somatic effects

A

Effects that are limited to the exposed individual and the specific area of exposure only

110
Q

General somatic effects

A

Effects that are limited to the exposed individual but the response to the radiation effects the entire body, not just the site of exposure

111
Q

Stochastic (probabilistic) effects

A
  • all or nothing effects (non threshold)
  • probability of effects increase in frequency with increasing doses of radiation
  • magnitude of response does not increase with increasing dose
112
Q

Non stochastic (deterministic) effects

A
  • existence of threshold
  • occurs at higher radiation doses
  • biologic effects increase in frequency and magnitude with increases in rad dose
  • ex: cataracts, erythema, fibrosis, and hematopoietic damage
113
Q

Ten day rule

A

Rad exposure to female in child bearing age should be limited to 10 days following the onset of menstruation

114
Q

Why are pediatric pts more radiosensitive?

A

Cells reproduce frequently

115
Q

Components of electromagnetic spectrum

A
  • visible light
  • ultraviolet light
  • gamma radiation
  • radio waves
116
Q

Becquerel (unit of radioactivity) describes what

A

Disintegrations per second

117
Q

Air kerma (unit of exposure) measures what

A

Quantity of ionization in air

118
Q

Gray measures what

A

Energy deposited in any material

119
Q

Sievert measures what

A

Dose to biologic material

120
Q

Effective dose formula

A 
EfD= equivalent dose (EqD) x Wt (tissue weighing factor)
EfD= radiation weighting factor x tissue weighting factor x absorbed dose
121
Q

Effective dose refers to what

A

Whole body dose

122
Q

What produces a potential difference within the xray tube during an exposure?

A

kVp

ARRT (9 decks)

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