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Rad Imaging/Protection Ch. 3 & 4 > Ch. 3-4 > Flashcards

Ch. 3-4 Flashcards

1
Q

What does kVp control

A

QUALITY, or penetrating power

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2
Q

Name 3 ways X-Rays interact with human tissue

A
  1. Interact with the atoms of the patient and become ABSORBED
  2. Intersect with the atoms of the patient and become SCATTERED
  3. Pass through the patient WITHOUT interaction
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3
Q

More Absorption =

A

Greater possibility of biological damage

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4
Q

Primary Radiation

A

What exits the tube

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5
Q

Anode

A

Target

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6
Q

Reasons tungsten/rhenium are used as target materials

A

High melting points
High atomic numbers

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7
Q

Inherent Filtration

A

Built-In

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8
Q

Added Filtration

A

A certain thickness of added ALUMINUM to “harden” the beam within the collimator

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9
Q

Combo of X-Ray tube glass wall and added aluminum placed within the collimator may be called

A

Permanent Inherent Filtration

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10
Q

Primary Radiation happens (before/after) it has gone through filtration

A

AFTER

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11
Q

SINGLE PHASE

A

100% voltage ripple

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12
Q

3 phase (6 pulse)

A

13% voltage ripple

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13
Q

3 phase (12 pulse)

A

4% voltage ripple

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14
Q

High Frequency

A

1% voltage ripple

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15
Q

Do all photons in a X-Ray beam have the same energy

A

No

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16
Q

The energy of the average photon is about 1/3 of the energy of the most energetic photon

A

Example:
100 kVp beam contains photons having energies of 100 KeV or less, with an average energy of approximately 33 KeV
100 divided by 1/3=33

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17
Q

Can the most energetic X-Ray photon have more energy than the set kVp

A

No, the photons can have no more energy than the set kVp

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18
Q

Photons that travel through the patient without interacting & reach the image receptor

A

Direct Transmission

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19
Q

(Possible/Impossible) to predict with certainty what will happen to a single photon when it enters human tissue

A

IMPOSSIBLE

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20
Q

(Possible/Impossible) to predict what will happen on the average when a large number of photons enter the human body

A

POSSIBLE

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21
Q

Absorbed Dose

A

D

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22
Q

Coherent Scattering

A

Occurs with low-energy photons, less than 10 KeV (kVp’s 1-50)
Wavelengths of incident and scattered are the same, so no new energy is absorbed by the atom, because no kinetic energy is lost
Small angle scatter
May result in small amounts of fog

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23
Q

Photoelectric Absorption

A

Interaction of a X-Ray PHOTON and an INNER SHELL ELECTRON
Involves ejection of an inner shell electron
Vacancy of inner shell is filled by an outer orbital shell electron
A difference in binding energies between the two electron shells forms a second photon
Photoelectron created ^
IMPORTANT MODE OF INTERACTION FOR PRODUCING USEFUL IMAGES

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24
Q

PHOTOELECTRIC ABSORPTION/Auger Effect

A

When an inner electron is removed (inner-shell vacancy) the energy given off by another electron filling his void can go on to eject another electron in the same atom
Instead of filling the “hole” , it ejects another electron

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25
Q

Probability of photoelectric absorption depends on

A

Energy (E) of the incident photons
Atomic number (Z) of the atoms comprising the body part

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26
Q

Energy of the incident photon decreases as

A

kVp decreases

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27
Q

Bone Atomic #

A

13.8

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28
Q

Soft Tissue Atomic #

A

7.4

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29
Q

Air Atomic #

A

7.6

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30
Q

Absorption vs kVp
As kVp decreases

A

Absorption increases

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31
Q

The whiter areas on radiographs

A

The higher the absorption
(Bone, Lead, Medal, Barium, ETC)

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32
Q

(Darker/Whiter) Less attenuation by the body part

A

Darker

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33
Q

(Darker/Whiter) More attenuation by the body part

A

Whiter
Ex: Knee replacements show up really bright because they absorb more

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34
Q

Increase window level =

A

Brighter, white, increased brightness

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35
Q

Decreased window level =

A

Darker, black, decreased brightness

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36
Q

Use of positive contrast medium- Iodine/Barium

A

Appears lighter because it increases photoelectric effect

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37
Q

Use of negative contrast medium-Air

A

Appears darker

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38
Q

Compton Scattering

A

Interaction with a loosely bound outer shell electron
X-Ray photon dislodges the electron from its outer shell, ionizing the atom
The freed electron is able to ionize other atoms and bounces around unit it finds an atom in need of another electron
The incident X-Ray photon that kicked out the electron continues on its way but in a new direction
Very Bad- Degrades image ‼️

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39
Q

Compton scattering scatter type

A

All-Directional scatter

40
Q

Pair Production

A

Occurs when a high-energy photon interacts with the NUCLEUS of an atom
The photon disappears and the energy is converted into a NEGATRON (ordinary electron) and a POSITRON (positively charged electron)
Positron and electron will annihilate each other

41
Q

Examples of unstable nucleus in PET

A

Fluorine-18
Carbon-11
Nitrogen-13

42
Q

WHAT DOES PET SCANNING DO
Ibuprofen

A

Reveals how tissues and organs are functioning
Utilizes a radioactive drug
Used a radioactive drug- may be injected, swallowed, inhaled depending on study
Collects in areas of body that have higher levels of chemical activity , showing up as “bright spots”

43
Q

Photodisintegration

A

Interaction that occurs at more than 10 MeV (3,000 kVp)
High energy photon is absorbed by a nucleus; completely destroying nucleus

44
Q

Higher mA=

A

Higher number of electrons being produced

45
Q

<5 rad

A

No immediate observable effects

46
Q

~5 to 50 rad

A

Slight blood changes

47
Q

~50 to 150 rad

A

Slight blood changes
Symptoms of nausea, fatigue, vomiting, etc..

48
Q

~150 to 1,110 rad

A

Severe blood changes
Could die within two weeks
Infection likely
May need a bone marrow transplant

49
Q

~1,100 to 2,000 rad

A

The probability of death increases 100% within one to two weeks
Symptoms are immediate
Gastrointestinal system is destroyed
Once GI System ceases to function, nothing can be done, care for comfort only

50
Q

> 2,000 rad

A

Death
Central Nervous System can no longer control anything including breathing and blood circulation
Nothing can be done, care for comfort only

51
Q

When were X-Rays discovered

A

November 8, 1895

52
Q

Somatic Damage

A

Result of excessive occupational radiation exposure for early pioneers and excessive exposure of patients

Cancer
Blood Disorders

53
Q

Unit used from 1900 to 1930 to measure radiation exposure

A

Skin Erythema Dose

54
Q

Was the Skin Erythema Dose accurate?

A

No
Tammy; “It’s like being out in the sun until you get a sunburn and then determining that you shouldn’t be in the sun that long or you will burn”
Everybody’s different

55
Q

SECOND INTERNATIONAL CONGRESS OF RADIOLOGY 1928
(The first was unable to make any decisions about the measuring effects of radiation) 1925

A

Acceptance of Roentgen (R)

56
Q

Early Tissue Radiation Reactions

A

Nausea
Fatigue
Loss of hair
Fever
Blood disorders

57
Q

Late Tissue Radiation Reactions

A

Cataracts
Reduced fertility
Sterility
Organ Atrophy (decrease in size due to cell shrinkage)

58
Q

Stochastic-Probabilistic

A

Mutational or randomly occurring biological changes, INDEPENDENT OF DOSE

59
Q

Stochastic effects

A

Cancer
Genetic effects

60
Q

When does ROENTGEN become internationally accepted

A

1937

61
Q

1934- committee recommendations of what daily limit dose

A

.2 roentgen
83x higher than what it is today‼️

62
Q

1936-committee recommendations of what daily limit dose

A

.1 roentgen
40x higher than what it is today

63
Q

Max permissible dose (MPD) replaces tolerance dose for radiation protection purposes
When?

A

Early 1950s

64
Q

When is (R) redefined to increase accuracy and acceptability

A

1962

65
Q

Is tolerance dose still accepted

A

No
NO DOSE IS SAFE‼️

66
Q

INTERNATIONAL COMMISSION ON RADIATION UNITS AND MEASURES (ICRU)
What did they adopt and when?

A

Adopted SI units for use with ionizing radiation in 1980

67
Q

National Council on Radiation Protection (NCRP)
What did they adopt and when?

A

Adopted SI units for use in 1985

68
Q

International Commission on Radiological Protection
What did they adopt and when?

A

Adopted the term EFFECTIVE DOSE in 1991
✅

69
Q

Exposure

A

Radiation quantity that expresses the concentration of radiation delivered to a specific area, such as the surface of the human body

70
Q

Precise Measurements of Radiation Exposure

A

Total amount of ionization a X-Ray beam produces in a known mass of air
Accomplished in a lab by using an ionization chamber

71
Q

Ampere

A

SI unit of electrical charge

72
Q

Air Kerma

A

SI quantity used to express how energy is transferred from a beam of radiation to a material (patient’s skin)
Can be used to express X-Ray tube output and inputs to image receptors

❗️K❗️inetic
❗️E❗️nergy
❗️R❗️eleased
PER
UNIT
❗️MA❗️ss

73
Q

Unit used to measure the quantity of air kerma

A

Gray (Gy)

74
Q

Air Kerma

A

Metric units of JOULE (energy) per kilogram
(J/kg)
May be stated in Gy

75
Q

When Gy is used to indication kinetic radiation energy absorbed in a MASS OF AIR, it is written as

(X-Ray Tube Output)

A

GYa
AIR-a

76
Q

When the Gy is used to indicate kinetic radiation energy absorbed in a MASS OF TISSUE, it is written as

(Transmitted X-Rays absorbed)

A

GYt
Tissue-t

77
Q

Dose Area Product (DAP)

A

Sum total of air kerma over the exposed area of the patients surface or, a measure of the amount of radiant energy that has been thrust into a portion of the patients body surface
Specified in units of nagy-cm2
Example:
Air kerma dose of 20mGy
Surface area exposed is 100cm2

DAP; 20mGy X 100cm2=2,000mGy/cm2

78
Q

What’s Absorbed Dose responsible for

A

Any biological damage resulting from exposure of the tissues to radiation

79
Q

X-Ray Photon, Beta, Gamma quality factor

A

1

80
Q

Thermal Neutron Quality Factor

A

5

81
Q

Fast neutron quality factor

A

20

82
Q

Low energy internal protons, Alpha particles, Multiple charged particles of unknown energy quality factor

A

20

83
Q

High energy external protons quality factor

A

1

84
Q

EqD

A

Product of the average absorbed dose in a tissue or organ in the body and it’s associated with awe chosen for the type and energy of the radiation in question

85
Q

Biological effects may be determined and expressed in..

A

Sv

86
Q

EqD=

A

D X Wr

87
Q

Sv=

A

Gy X Wr

88
Q

Radiation Weighting Factor (Wr)

A

Must be used when determining EqD
Used for radiation protection purposes to account for differences in biological impact among various types of ionizing radiation
Places risks associated with biological effects on a common scale

89
Q

Annual Whole Dose Limits
General Public

A

1mSv

90
Q

EfD

A

Measure of the overall risk of exposure to humans from ionizing radiation
Both the effect of type of radiation and the variability in radio-sensitivity of the part

91
Q

EfD=

A

D X Wr X Wt

92
Q

mSv to mrem

A

X100

93
Q

Collective EfD

A

Used in radiation protection to describe internal and external dose measurements
Quantity used to describe exposure of a POPULATION OR GROUP
Person-Sievert

94
Q

Total Effective Dose Equivalent (TEDE)

A

Radiation dosimetry quantity that was defined by the NRC to monitor and control human exposure to ionizing radiation

95
Q

TEDE

A

Designed to take in account ALL possible sources of radiation exposure

Rad Imaging/Protection Ch. 3 & 4 (1 decks)

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