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Rad 520 Physics > Review Questions > Flashcards

Review Questions Flashcards

1
Q

Acronym for older KV machines

A

GCSOS

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2
Q

Energy for Grenz - Ray Therapy

A

20 KV

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3
Q

Energy for Contact Therapy

A

40-50 KV

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4
Q

Energy for Superficial Therapy

A

50-150 KV

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5
Q

Orthovoltage

A

150-500Kv

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6
Q

Supervoltage

A

500-1000kV

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7
Q

What is difference between kVp and KeV

A

kVp is manmade and polyenergetic
KeV is monoenergetic

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8
Q

Van De Graff generator, linear accelerator, betatron, microtron, and gamma ray like Co-60

A

Megavoltage Therapy

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9
Q

Which megavoltage machine has a donut?

A

Betatron (circular accelerator)

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10
Q

Betatron Energy

A

6-40MeV

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11
Q

Which megavoltage machine has the downside of low dose photon rate due to the high need for electrons

A

Betatron

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12
Q

Which megavoltage machine has the downside of 1000x the need for photons compared to electron alone

A

Betatron

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13
Q

For microtron the more energy of electrons =

A

Increase radius traveled

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14
Q

Megavoltage machine with oscillating electric field of a microwave accelerates electrons

A

Microtron

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15
Q

Van de Graff Generator

A

2Mv-25MV

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16
Q

Tomotherapy SAD

A

85cm

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17
Q

Tomotherapy energy for tx and imaging

A

6MV for fx; 3.5 for imaging

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18
Q

Why does tomo not have a flattening filter

A

Blurs itself out with 360 degree circulation

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19
Q

Cyclotrons main clincial use

A

Protons

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20
Q

Cyclotrons: Increase energy means_____

A

increased depth of Bragg Peak

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21
Q

How many cyclotron can support how many gantry heads?

A

3-4

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22
Q

What is the main source of protons

A

Hydrogen gas

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23
Q

Cyclotron can also be used to

A

make radionuclides

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24
Q

Cyclotron shape is?

A

double D’s

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25
Q

Typical energy of proton therapy

A

70-250 MV

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26
Q

Spread out bragg peak (SOBP)

A

Variety of energies which are used to cover variety of energies

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27
Q

What has the highest binding energy?

A

Inner electron shell

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28
Q

how to calc the characteristic xray energy

A

it is M-K shell; M-L
(difference in binding energies)

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29
Q

Why is atomic mass not a round number?

A

Weighted average due to abundance in isotopes

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30
Q

Resting mass for electrons and positrons

A

9.11 x 10^-31

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31
Q

Resting mass is in

A

kg

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32
Q

Resting mass for protons

A

1.672 x 10 ^-27

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33
Q

Resting mass for Neutrons

A

1.675 x 10 ^-27

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34
Q

Rest energy for proton

A

938.3 MeV

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35
Q

Rest energy for Neutrons

A

939.6 MeV

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36
Q

Mean life

A

1.44(T1/2)

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37
Q

Decay constant is

A

ln2/(half life)

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38
Q

Electron capture is similar to and why

A

B+ since proton is becoming neutron

39
Q

MODES of DECAY

40
Q

Electron capture is more likely with

A
  • Higher Z # or nucleus with lots of protons
41
Q

Electron capture is when

A

an orbital e- gets captured by the nucleus, combines with proton and become a neutron

42
Q

Compton effect; 90 degree scatter results in

43
Q

Compton effect; 180 degree backscatter results in

44
Q

Increased energy does what to forward peak

A

increases forward peak

45
Q

Pair Production threshold

46
Q

Neutron contamination is more likely with

A

10MV or higher

47
Q

Total kinetic energy of all particles is the same before and after collison

A

Elastic collision

48
Q

Kinetic energy is lost (lost energy goes to excitation, ionization or bremsstrahlung)

A

Inelastic collision

49
Q

Electron stopping power

50
Q

atoms of the target become ionized or excited and lead to events resulting in biologic change

A

Direct action

51
Q

Measure of the rate at which energy is transferred from ionizing radiation to soft tissue

A

LET (Linear Energy Transfer)

52
Q

Best absorbers of neutrons

A

hydrogenous materials

53
Q

Where is a beam defined at for flatness

A

10cm depth in water
80% (cant do edges due to penumbra)

54
Q

How does flatness change with a depth shallower than 10cm and a depth deeper than 10cm

A

Shallow has lateral horns
Deeper has a middle hump

55
Q

Lateral horns are quantity or quality

A

quantity ( number of photons)

56
Q

Flatness is quantity or quality

A

quantity ( number of photons)

57
Q

flattening filter affect on output

58
Q

Flattening filter affects quality or quantity

A

quantity ( number of photons)
Can be quality as it hardens the beam

59
Q

can you use same flattening filter for multiple energies

60
Q

A flattening filter__________ The average energy and____________ the total radiation quantity

A

Increases , decreases

61
Q

Which of the following decay modes is most prominent in the heavier elements

62
Q

An increase in KVP has a________ effect on electron output - while MAs has A___________ effect

A

Squared / direct

63
Q

Which of the following photon interactions results in a scattered photos w/ less energy & an ejected orbital electron

64
Q

Which of the following radiation measurement devices utilize a p-type and n type junction

A

Silicon diode

65
Q

Which of the following organizations would be utilized to calibrate an ion chamber for a clinical site

66
Q

How would an increase in SSD affect geometric penumbra width

67
Q

What factor has a indirect relationship w/ penumbra

68
Q

Compared to photon mode electron mode uses a________ machine current and the___________ on the carousel

A

Lower / scattering foil

69
Q

Half life of iodine 131

70
Q

Half life of cesium 131

71
Q

Half life of palladium 103

72
Q

Half life of iodine 125

73
Q

Half life of cobalt 60

A

5.26 years

74
Q

Half life of indium 192

75
Q

Half life of cesium 137

76
Q

Half life of radon 222

77
Q

Half life of radium 226

78
Q

A phenomenon in which one orbital electron taken by the nucleus and transforms a proton in to a neutron

A

Electron capture

79
Q

Electron capture is shown in a nuclear decay on what side of the formula

80
Q

Electron capture is competeing conversion with?

A

Positron decay

81
Q

Another name for characteristic xrays produced by interactions of photons with the atom is

A

fluorescent xrays

82
Q

Auger electrons ar more probable with

A

low z numbers

83
Q

Decay mode atom with a deficit number of neutrons and their n/p ratios are lower

A

Positron emission

84
Q

Mass energy difference between the parent and daughter atoms for B+ must be

A

1.02 MeV (positron emission)

85
Q

Decay mode atom with excessive number of neutrons and their n/p ratios are high

A

Negatron emission/ B-

86
Q

Mode of decay more common with high atomic number radiunuclides

87
Q

a negatively charged electron emitted from a nucleus.

A

β− particle (negatron)

88
Q

a positively charged electron emitted from a nucleus.

A

β+ particle (positron)

89
Q

Mode of decay that is likened into “internal photoelectric effect”

A

Electron capture

90
Q

Fusion of _______ into _______is the source of our sun’s energy.

A

hydrogen nuclei; helium nuclei

91
Q

Example of Nuclear reactions

A

Fission/ fusion

92
Q

Linac treatment head is shielded by

A

lead, tungsten, or lead–tungsten alloy

Rad 520 Physics (5 decks)

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