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RadioBiology > Ch 2: Sources Of Radiation And Chromsome Damage > Flashcards

Ch 2: Sources Of Radiation And Chromsome Damage Flashcards

1
Q

Most of the damage produced by xray is the result of _____ damage/action

A

Indirect

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2
Q

Coherent scattering occurs with the ______ energy photons with no energy transfer

A

Lowest

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3
Q

Which effect most commonly occur within diagnostic X-rays?

A

Photoelectric effect

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4
Q

Which interaction is most useful with PET Scan?

A

Pair production

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5
Q

Which effect is the major interaction that occurs in radiation therapy?

A

Compton effect

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6
Q

________ is not always a lethal chromosomal aberration

A

Translocation

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7
Q

Production of ________ radiation an the ________ process/effect are very similar processes.

A

Characteristic: photoelectric

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8
Q

________ radiation is the key for the generation of therapeutic X-rays

A

Bremmsstrahlung

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9
Q

The target material in linacs is?

A

Tungsten

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10
Q

T/F

All photons that are produced have the same energy

A

False

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11
Q

In general, what type of DNA damage is most likely to result in cell death?

A

Double strand breaks

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12
Q

Linacs are cooled by?

A

Cold water

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13
Q

Most chromosomal damage results in?

A

Healing by restitution

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14
Q

_______ damage can only occur through the use of high LET particles

A

Direct damage

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15
Q

Indirect action is effective by creating ?

A

Creating free radicals that damage DNA

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16
Q

T/F

Different energies are generated when electron hit tungsten target and is generated in different direction.

A

True

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17
Q

For the target, in general, we want high Z (atomic number) materials. Why?

A

Heavy metals that has a high z number emits higher intensity bremsstrahlung radiation. We normally uses Tungsten

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18
Q

Explain why we use Tungsten as our target

A

High z number
Conducts heat very well, therefore it will dissipate heat generated by the bombardment of electrons.
High melting point (3695K)

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19
Q

What are the 2 types of energy produced when high energy electron hit the target?

A

Heat (99 percent)

Photon (1 percent)

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20
Q

Bremsstrahlung radiation is the ________ (high/low) energy radiation.

A

High

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21
Q

_________ radiation is the key radiation for generation of therapeutic radiation.

A

Bremsstrahlung

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22
Q

Bremsstrahlung radiation occurs when an electron __________________________.

A

Passes close to the nucleus

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23
Q

What is the Coulomb force and in which radiation form is it found in?

A

Coulomb force is found in Bremsstrahlung radiation. It is the force that control the electron and positron interaction. It interacts and slow the electron.

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24
Q

T/F

Bremsstrahlung radiation may have 1 or more reactions.

A

True

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25
Q

__________ is the force that interact and slow the electron.

A

Coulomb force

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26
Q

Characteristic is the _________(higher/lower) energy radiation.

A

Lower

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27
Q

___________ controls the electron ad positron interaction within the Bremsstrahlung radiation

A

Coulomb force

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28
Q

What are the 2 radiation processes that occurs in the Tube?

A

Bremsstrahlung and Characteristic radiation

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29
Q

Why does the electron “curve” as it gets closer to the nucleus during Bremsstrahlung radiation?

A

Because the electron has a negative charge and the nucleus has a positive charge, the positive nucleus causes it to curve and that curve slows down the electron, causing the production of photons.

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30
Q

Unlike Bremsstrahlung, Characteristic radiation interacts with _______.

A

Another electron

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31
Q

Describe characteristic radiation.

A

The incoming electron hits a shell electron (K,L,M,N), causing that electron to be excited and ejected. Another electron from the outer shell falls in to fill the gap and the difference in energy from higher to lower shell produces photons.

32
Q

How do you calculate the energy of the ejected electron in the characteristics radiation.

A

Primary incoming electron energy subtract the energy of the electron shell that got hit/ejected.

33
Q

The energy of the photon produced in characteristic interaction is the _______(same/diff) energy as the original shell energy that fell in to fill up the gap.

A

Same energy

34
Q

As the electron ride the waves of the accelerator tube of a Linac, the electron ___________ energy and continues to _________.

A

Picks up more energy; increase

35
Q

Why do we use bending magnet in Linacs?

A

The bending magnet bends the beam to hit the target.

36
Q

As you increase energy of the photon, you also ________(increase/decrease) their penetrability. That’s why Linacs are use in the MV range for penetration.

A

Increase

37
Q

1MV = _____kV

A

1000kV

38
Q

At the range of ______ to ______, we must switch to Linacs because Linacs will allow us to produce electron as such high levels.

A

500kV to MV

39
Q

The ________ process dominates in the use of Linacs .

A

Compton process

40
Q

What are the 5 typical interaction of xray with matter ?

A 
Photoelectric
Pair production 
Photo disintegration
Compton 
Coherent scattering
41
Q

____________ occur at very low energy and no energy is transferred.

A

Coherent scattering

42
Q

_____________ is very similar to characteristic radiation.

A

Photoelectric process

43
Q

T/F

Photoelectric occurs in the tube

A

False.

Photoelectric occurs inside the patient.

44
Q

_______ produces low energy X-rays.

A

Photoelectric

45
Q

_______ is more common in diagnostic X-rays

A

Photoelectric

46
Q

____________ requires very high energy incoming photon to produce both an electron and positron.

A

Pair production

47
Q

_________ can only occur when incoming photon is greater than 1.02 MeV

A

Pair production

48
Q

What is the major effect (not radiation)that we see occur in therapeutic oncology?

A

Compton effect

49
Q

The scatter photon that is produced during the Compton effect will eventually _____ it’s energy and will start to cause the photoelectric effect or a characteristic effect or interact with another electron to cause another Compton effect

A

Loose its energy

50
Q

What are the 2 type of xray damage

A

Direct (20 percent)

Indirect (80 percent)

51
Q

______ damage (direct/indirect) will deposit its energy directly into the target (aka DNA) and with high enough energy, will cause the DNA to break.

A

Direct damage

52
Q

What process do we use to model/generate the dose field and to figure out the isodose line

A

Compton process

53
Q

Direct damage requires high let such as ______ and _______

A

Neutrons and alpha particles.

54
Q

During indirect damage, Compton process will occur, and the Compton electron (the electron that got kicked out of its shell) will interact with water and produce _________ .

A

Free radicals

55
Q

_________ are highly unstable and reactive and will damage DNA

A

Free radicals

56
Q

Indirect damage interacts with ______ and produces _______.

Direct action damage _______ directly.

A 
Indirect= water and produces free radicals 
Direct = DNA
57
Q

Alpha particles and neutron has high LET and will/interact with ________ and cause ______ damage

A

DNA; direct damage

58
Q

Direct damage usually ends up as a ________ ________ break

A

Double strand

59
Q

T/F

Double strand break (DBS) is easier to repair and the effect to the DNA is not permanent

A

False.

DSB is harder to break and will cause more permanent DNA damage

60
Q

Radiation damage to DNA can be divided into 4 categories.

A 
4 categories are: 
Base damage 
Single strand break (ssb)
Double strand break (dsb)
Crosslinking
61
Q

Change or loss of a base is __________ damage

A

Base damage

62
Q

_______ is the break in the backbone of one chain of the DNA molecule

A

Single strand break

63
Q

_______ is the break in both chains of the DNA molecule. Occurs in direct damage.

A

Double strand break

64
Q

_________ occurs either within the DNA molecule (intrastrand) or from one molecule to another (DNA intrastrand or DNA protein)

A

Cross linking

65
Q

Spallation products are produced when…..

A

When neutron interacts with oxygen or carbon

66
Q

T/F

Regardless of severity of the consequences, loss or change of a base is considered a type of mutation

A

True

67
Q

T/F

Single strand break are most likely efficiently repaired, wit little, if any, long term consequences to the cell.

A

True

Because it have been found that SBS are relatively inconsequential in terms of cell killing.

68
Q

T/F

For a break to be considered a “double strand break”, the breaks must be adjacent to each other.

A

True

They are essentially single strand break when it’s not adjacent to each other

69
Q

This type of damage to the DNA molecule is significant and is more likely to be more difficult for the cell to repair accurately.

A

Double strand break (DSB)

70
Q

Unlike single strand break, ___________ do show a reasonable correlation with cell killing. If repair does not take place, the DNA chains can separate , with greater consequences to the life of the cell.

A

Double strand break (DSB)

71
Q

How can interstrand crosslink can be produce?

A

Between the 2 complementary DNA strand or between completely different DNA molecules.

72
Q

T/F
We are concerned most about SSB. When SSB are close by on opposing strands, it is like a DSB which is hard to repair because the strand or chromosome breaks.

A

True

73
Q

T/F

SSB cause cellular death

A

False.

DSB may cause cellular death

74
Q

What are the 3 lethal chromosome aberrations

A

Dicentric
Bridge
Loop/ring

75
Q

T/f

Acentric aberration is lethal. Di-centric aberration is NON-lethal

A

False

Acentric= non-lethal
Di-centric= lethal due to major lose of genetic info when the dicentric piece gets pulled apart due to having 2 centromeres
76
Q

T/F

Translocation is not lethal.

A

True

RadioBiology (5 decks)

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