Chapter 3 Flashcards
1
Q
true or false: in the law of bergonie and tribondeau, stem/immature cells are more radiosensitive than mature cells
A
- true
2
Q
true or false: younger tissues are more radiosensitive than older tissues
A
true
3
Q
true or false: the higher the metabolic rate (the energy the cells use), the more radiosensitive it is
A
true
4
Q
true or false: the greater the proliferation (rate of cell division) and growth rate for tissues, the greater the radiosensitivity is
A
true
5
Q
why are our bodies not created equal?
A
because our cells are not created equally
6
Q
what does the law of bergonie and tribondeau conclude?
A
that compared to a child or mature adult, the fetus is the most radiosensitive
7
Q
define radiosensitivity
A
- the effects that our cells undergo and the probability of damage or recovery when irradiated
8
Q
define radioresistance
A
- how resistant the cell is to radiation
9
Q
what is one main factor of determining radiosensitivity?
A
- the proliferation (rate of cell division) rate of that cell and the rate of cell division (mitosis) rate
10
Q
true or false: the faster the cell divides, the less time it must repair itself from damage before dividing into another damaged cell
A
true
11
Q
define proliferation
A
- the rate of cell division is
12
Q
what cells have the highest sensitivity?
A
- cells that are immature, undifferentiated, precursor or stem cells
13
Q
define direct effect
A
- ionization occurs directly with a molecule
14
Q
define indirect effect
A
- ionization occurs with water and transfers ionization to target molecules
15
Q
define fraction theory
A
- radiation dose broken into smaller doses spread out over a period rather than given all at once
16
Q
what are the highly radiosensitive cells?
A
- lymphocytes
- spermatogonia
- erythroblasts
- intestinal crypt cells
- DNA
17
Q
what are intermediate radiosensitive cells?
A
- endothelial cells
- osteoblasts
- spermatids
- fibroblasts
- RNA
18
Q
what are low radiosensitive cells?
A
- muscle/nerve cells
- chondrocytes
19
Q
true or false: cell radiosensitivity depends on what part of the cell cycle they’re in
A
true
20
Q
define irradiated
A
- exposed to radiation
21
Q
what occurs when a cell is irradiated in the cell cycle?
A
- mitosis is slowed down
- interphase death = cell death occurs before entering mitosis
- cell death occurs
22
Q
what part of the cell cycle is most radiosensitive?
A
- M phase/mitotic phase (prophase, metaphase, anaphase, and interphase)
- G1 phase (1st growth phase)
- early S phase (where DNA replication occurs)
23
Q
When looking at a graph that deals with age factors consisting of the fetus in the uterus, childhood, adult, and age, which portion has the highest radiosensitivity?
A
- fetus in the uterus (womb)
- this is due to the fetus having immature cells, which makes them vulnerable to radiation
24
Q
define LET
A
- linear energy transfer
- a measure of the rate at which energy is deposited as a charged particle travels through matter
- units of measurement: keV/mm (micrometer)
- is the function of the physical characteristics of radiation (mass and charge)
25
explain low LET
- contains electromagnetic x-rays (x-rays and gamma rays)
- they produce few and thinly dispersed interactions due to their fast moving electrons
- lose their energy at a low rate when passing through tissues
26
explain high LET
- consists of alpha particles and neutrons
- highly ionizing
- more likely to interact with tissues
- lose their energy quickly
- produce several ionizations with a short distance
27
true or false: a diagnostic x-ray with an LET of 3kev/mm are considered to be low when compared to other radiations
true
28
how much RBE (relative biologic effectiveness) does a diagnostic x-ray have?
- approximately 1
29
define division delay
- slowing down of cell mitosis
- low radiation dose = delay cell mitosis
30
define RBE
- relative biologic effectiveness
- a comparison of a dose of test radiation to a dose of 250 keV x-ray that produces the same biologic response
- measures the biologic effectiveness of radiations having different LET's
- comparing dose of test radiation to a dose of 250keV x-ray, which produces the same biologic response
31
what's the formula for RBE?
RBE = dose in rads from 250 keV x-rays necessary to produce a given effect / dose in rads of test radiation necessary to produce the same effect
RBE = dose in rads from 250KeV x-rays / dose in rads of test radiation
32
what factors influence RBE?
- radiation type
- cell or tissue type
- physiology condition
- biologic result being examined
- radiation dose rate
33
what's the relationship between LET and RBE?
- direct relationship
- when LET increases, RBE increases
34
define OER
- oxygen enhancement ratio
- dose of radiation that produces a given biologic response under anoxic (no oxygen) conditions divided by the dose of radiation that produces the same biological response under aerobic (with oxygen) conditions
35
define anoxic
- no oxygen
36
define hypoxic
- lacking oxygen
37
what's the formula for OER?
OER = dose that produces a given biologic response under anoxic conditions / dose that produces the same biologic response under anaerobic conditions
38
true or false: OER is most effective with low LET radiation
true
39
true or false: OER is less effective with high LET radiation
true
40
true or false: an increase in OER increases LET
true
41
what happens when cell mature?
- radiosensitivity declines
- as we mature, we become radioresistant
- once we hit old age, we become radiosensitive again
42
define direct interaction
- takes place when an original ionization incident happens on that macromolecule
- Ex.) DNA, RNA, protein, enzymes
- if a macromolecule is ionized, it's considered abnormal and is damaged
43
define indirect interaction
- ionization incident that takes place on a distant non critical molecule, which then transfers that energy to another molecule
44
true or false: radiation interactions with humans are mostly indirect
- true
- this is due to the human body being 75% of water
45
define radiolysis
- when water is irradiated, it gets ionized, producing a free radical
- human body containing 75% of water
46
what's the principal cause of effects from radiation?
- the irradiation of water that causes indirect effects
47
define free radical
- an uncharged molecule containing a single unpaired electron (ion) in the outermost shell/valence shell
- chemically unstable
- highly reactive
- can quickly interact with other molecules and interfere with their bonds
48
what are the results of radiolysis?
- H+ and OH- (ion pair)
- H* and OH* (free radicals)
- the free radicals can either create a water molecule or damage other macromolecules
49
true or false: if OH* and H2O2 (hydrogen peroxide) causes 2/3rds radiation damage
true
50
define vitro
- outside of the body or cell
- irradiating macromolecules requires a significant dose of radiation to create a measurable effect
51
define vivo
- inside the cell
- irradiating macromolecules show cells in their natural state
- more radiosensitive
52
define main-chain scission
- occurs when the thread or backbone of a long chain molecule is broken
- reduced to smaller molecules
- viscosity (thickness) is reduced
53
define cross-linking
- causes the macromolecules to connect to another macromolecule, or to another section of the same molecule
- viscosity is increased
54
define point lesion
- may cause slight molecular changes, which in turn cause the cell to function incorrectly
- occur in low doses of radiation
- responsible for the late radiation dose
55
define dose -response relationships
- graphical relationship between observed effects (response) from radiation and dose of radiation received
1. they're either linear or nonlinear
2. they're either threshold or non-threshold
56
define linear
- an observed response is directly proportional to dose
- doubling the dose of radiation will double the response
57
define nonlinear
- an observed response is not directly proportional to the dose
- doubling the dose of radiation does not double the dose of the response
58
define threshold
- a point where biologic response occur
- implies there is a "safe" amount of dose delivered
- curves can be linear, sigmoid, or curvilinear
- doesn't start at zero
59
define nonthreshold
- any radiation exposure is harmful/causes a response in the body
- no safe level
- curves can be linear, curvilinear
- all start at zero
60
define linear quadratic dose-response curves
- low doses of low LET radiation follow a linear quadratic dose-response
- low dose = linear curve
- high dose = curvilinear curve
- curve is nonthreshold
61
define nonlinear dose-response relationships
- sigmoid
- contains threshold with no observable effects occuring
- with sigmoid dose-response, there a nonlinear relationship between dose and effect
- not directly proportioned
62
define target theory
- effect of radiations by direct hits on sensitive cellular targets
- DNA is considered a critical molecule (because it's not abundant)
- target interactions occur randomly
63
define hit
- when chromosomes (or target) is/are irradiated
- interactions can either be direct or indirect
- represent critical damage to DNA
64
define how target theory depends on LET
- with an aerobic condition, the indirect effect is intensified due to more free radicals formed
- this increases the likelihood of a hit
65
define bystander effect
Treatment of cells with low doses of radiation results in the release of specific factors outside the cell that seem to be responsible for biological changes in cells not directly exposed to radiation.
66
define repopulation
- allow cells to replenish and repopulate following injury or interaction to ionizing radiation to lessen the likelihood of damage
67
define protraction
- the time during which a course of radiation is given (spread out dosage)
68
when were x-rays discovered?
- November 8, 1895
69
who found x-rays?
- Wilhem
70
what year was radium discovered?
- 1898
71
who discovered radium?
- Pierre and Marie Curie
72
who invented the fluoroscope?
- Thomas Edison
73
what year was the fluoroscope invented?
- 1898
74
who was Thomas Edison's assitant?
Clarence Dally
75
How did Clarence Dally die?
- due to cumulative exposure to radiation
76
who discovered mutations through experiments with fruit flies?
- Herman Muller
77
what did Herman Muller discover?
- mutations through experimenting with fruit flies
78
define rad
- Radiation absorbed dose
- also known as Gray
- patient dose
79
define rem
- radiation equivalent man
- also known as sievert
- occupational dose
80
define roentgen
- exposure in air
- also known as Coulumb/kilogram
- x-ray in air
81
define curie
- radioactivity
- also known as becquerel
- x0ray quantity
82
define NCRP
- national council of radiation and protection
- sets the standard for dose limitations for occupational workers and the public exposure
83
what's the formula for occupational dose and patient dose
1 RAD = 1 REM
100 RADS = 1Gy (Gray)
84
define epilation
- hair loss
85
define erythema
- skin reddening
86
define desquamation
- skin peeling
87
define inflammation
- skin swelling and reddening
88
define tissues
- collection of cells
89
define organs
- collection of tissue
90
define systems
- collection of organs that work together
91
define organisms
- all systems working together
- Ex.) human
92
what are the functions of cells?
- metabolism
- growth
- irritability
- adaptability
- repair
- reproduction
93
what's the normal number of chromosomes in a human?
- 46
- diploid or 2n
94
define haploid number?
- the number of chromosomes in germ cells
95
define germ cells
- reproductive cells
- also known as somatic or gamete cells
96
what's the name of a male germ cell?
- spermatozoa
97
what's the name of a female germ cell?
- oocytes
98
When are cells most radiosensitive?
- during division
- cells are immature
99
when are cells radioresistant?
- after division is complete
- when the cell is mature
100
define interphase
- subdivided into G1, S, and G2 phase
101
define G1 phase
- "resting phase"
- 1st growth phase
- normal metabolic roles
102
define S phase
- cell cycle is completed and "mature" (radioresistant)
- DNA replication
103
define G2 phase
- gap or growth phase
- the process of mitosis
- 2nd growth phase
104
what happens after G2 phase?
- the cell DNA replicates itself and begins a cell cycle M phase
- mitotic phase
105
define prophase
- first stage
- chromosomes migrate towards opposite poles of the cell
- produce spindle fibers that extend across the equator
106
define metaphase
- 2nd stage
- the cells are lined up at the equator
- lined up in the middle of the
107
define anaphase
- 3rd stage
- the centromeres divide and the sister chromatids detach as they are pulled to opposite poles
108
define telophase
- 4th final stage
- the sets of chromosomes become longer, thinner and indistinct as they reach the poles of the cell
- cell division is complete
109
define mitosis
- the process of cell division in which nucleus and the cytoplasm divide
110
define meiosis
- the process of cell division in which the nucleus and the cytoplasm divide to form 2 identical cells
- cells divide twice
- chromosomes duplicate once
111
What happened in 1896
- antoine and henri becquerel observance being given off by uranium containing substances
112
As LET ____________, the RBE ______________
increase; increase
113
Tissue is _______ radiosensitive under high oxygen conditions and _________ radiosensitive under hypoxic conditions.
more; less
114
A _________ response to radiation is directly proportional to the dose received.
linear
115
If a response to radiation is expected, no matter how small the dose, then that dose-response is ________________
nonthreshold
116
Radiation induced genetic damage follows a ___________________ dose-response relationship
linear nonthreshold
