C. biological effects of radiation part 2 Flashcards

1
Q

Dose-response relationships are represented by a

A

graph

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2
Q

Dose- response graphs show information on the cells response to radiation and cell survival in the

A

presence of radiation

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3
Q

Dose- response graphs are either

A

linear or nonlinear

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3
Q

___ graphs represent a response that is not proportional to the dose recieved

A

non- linear

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4
Q

____ graphs represents a response that is directly proportional to the dose recieved

A

linear

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5
Q

________ on a Dose-response graph represents a dose after which only 37 percent of the cell population will survive

A

Do or D37

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6
Q

Cells that are _____ have a low Do because it takes a lower dose to kill all but 37 percent of cell the cell population

A

radiosensitive

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7
Q

Cells that are ______ have a high Do because it takes a higher dose to kill all but 37 percent of the cell population

A

radioresistant

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8
Q

_______ is the number of cells or the target on dose response graph

A

extrapolation number (n)

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9
Q

The extrapolation number (n) is usually about

A

2-10

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10
Q

___ is the quasi-threshold dose, which represents the cells capability to repair

A

Dq

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11
Q

Dq is also known as the

A

shoulder region

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12
Q

Graphs with multipl Dq/ shoulder regions represent

A

multiple factors

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13
Q

_____ is the most sensitive part of the cell

A

DNA

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14
Q

where is DNA located

A

nucleus

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15
Q

When radiation interacts with the target it is called a

A

direct hit

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16
Q

Law of _________: explains the effect of radiation is greater for cells that divide rapidly, cells that are immature with long mitotic future, and undifferentiated

A

Bergonie and Tribondeau

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17
Q

Stem cells are ______ than mature cells

A

more radiosensitive

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18
Q

Blood forming cells are _____ because of their rapid division rate

A

more radiosensitive

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19
Q

_______ = the extent of radiation damage can change depending on the cells external factor before, during, or after delivery of radiation

A

Ancel and Vitemberger

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20
Q

________ is the rate that energy is deposited through matter as it travels through it

A

Linear energy transfer (LET)

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21
Q

LET is another expression of

A

radiation quality

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22
Q

X rays and gamma rays have ___ LET

A

low - goes farther

23
Q

Protons and alpha particles have ___ LET

A

high - goes shorter distances

24
On a dose- response relationship graph, high LET is represented by a steeper curve and shoulder is either smaller than normal or nonexistent because more cells are
killed faster do not have a chance of repair
25
_________ = the ability for the type of radiation to produce biological damage
Relative biological effectiveness (RBE)
25
Higher LET= ___ RBE
higher
26
Lower LET = __ RBE
lower
27
let equations ??
28
Examples of radiation types with low RBE are
diagnostic x-rays, gamma rays, MV x-rays, electrons, etc.
29
Examples of radiation types with higher RBE are
heavy nuclei, alpha particles, fast neutron, etc.
30
Therapeutic ratio equation is
normally tissue tolerance dose / tumor lethal dose
31
On the linear accelerator, lower dose rates cause less damage than
higher dose rates
31
ideally, tumor lethal dose should be less than the normal tissue dose to avoid
damage to healthy tissue
32
High dose rates cause more
side effects more rapidly
33
TBI uses ___ dose rates
high
34
___ is the radiation dose than would cause 50% of population to die in 30 days
LD 50/30
35
LD 50/30= ___ SV
4-5
36
The presence of oxygen during a radiation treatment will greatly increase the
radiosensitivity of the cell
37
Tissues are more radiosensitive when in an
oxygenated, or aerobic, state
38
Typically, cells within a tumor are in an ___ state
Anoxic - no oxygen
39
_____ for xrays is 2.5-3.0 in human cells
Oxygen enhancement ratio (OER)
40
OER is higher for ___ LET radiation
Low - due to high LET radiation already being very damaging
41
OER is lower for ___ LET radiation
high
42
A ______ effect is when radiation hits the target (DNA)
direct
43
A ____ effect is when radiation first hits water within the cell, which then damages DNA
indirect
44
Indirect effect lead to
radiolysis and free radicals in the cell
45
WHat is a common free radical in the cell
hydrogen peroxide ( H2O2)
46
Free radicals can lead to damage of
DNA
47
Chromosome damage can be
single or double strand breaks
48
_______ breaks can lead to dicentric fragments, acentric fragments, translocation and/or ring formation
single strands
49
_____ breaks can lead to deletions and inversion
double - stand
50
A cell response to radiation is cell death, which is known as
aptosis
51
The most radiosensitive cell cycle is th
M phase (also end of G2)
52
The most radioresistant cell cycle is the
S phase