Rad Bio Flashcards
2 purines are ?
adenine & guanine
2 pyrimidines are?
thymine & cytosine
adenine binds with
thymine
guanine binds with
cytosine
mitosis phases (4)
- prophase
- metaphase
- anaphase
- telephase
what happens in prophase
- spindle forms
- membrane begins to disappear
what happens in metaphase
chrom line up @ equator
what happens in anaphase
migrate to opp poles
telophase main process
division (cytokenesis)
what happens during G1?
rapid growth & active metabolism
S phase fxn & sensitivity?
- DNA synthesis
- least sensitive
G2 fxn & sensitivity?
- prepare for cell division
- highly sensitive
M fxn & sensitivity?
- cell divides
- most sensitive
what happens during G0?
resting phase
linear quadrant model surviving fx = ?
alpha (a)dose + beta (B) dose squared
alpha (a) proportional to:
dose
beta (B) proportional to:
dose squared
tumor display for a/B ratio?
tumors tend to display higher a/B ratio than normal tissue due to lack of repair fxn
tumor typical value of a/B
10Gy
norm tissue typical value of a/B -late effects
3 Gy
LET definition
rate @ which E is deposited as charged particle travels thru matter
EMR mass?
no mass
quantum theory of EMR
E is photon traveling in straight but diverging lines
RBE stands for
relative biologic effect
RBE definition
ability to produce specific biologic response w/diff LET
what happens in chromosome with damaged base?
- change/loss in base
- mutation or abberation
what happens with double strand break chromosome damage?
both chains break
Mammalian cell survival curve shape
semi-log
reciprocal of slope & expression of radiosensitivity of cell population value is?
b/n 1-2 Gy
radiosensitivity = ? Do
low
radioresistant = ? Do
high
high dose curve shape
shallow curve
curve shape for low doses
steep curve
low LET shoulder on cell survival curve
broad shoulder
high LET shoulder on cell survival curve
no shoulder
division delay dependent on
dose
interphase death means
cells die before dividing
repair SLD radiation type
x-ray, gamma only
repair PLD occurs when
post irradiation conditions are modified
inherent sensitivity means
when & if cell divides
Bergonie & Tribondeau stated
cell division critical to selective cell killing
Ancel & Vitemberger stated
inherent susceptibility of any cell to damage by radiation is same but time of appearance of damage is different
appearance of rad damage influenced by ? stress
biological stress
greatest stress on cell- ? necessity
necessity for division
Rubin & Casarett 5 categories of cell populations
VIM, DIM, multipotential conn tissue, RPM, FPM
VIM definition
vegetative intermitotic delay
DIM stands for
differential intermitotic delay
RPM stands for
reverting post mitotic delay
FPM stands for ? & do cells divide?
- fixed post mitotic delay
- do NOT divide
stromal dept found in?
all organs & tissues
3 factors that affect cell/tissue after radiation
physical, chemical, biological
physical factors (3)
- LET
- RBE
- dose rate
large shoulders for neutrons exhibit ? RBE
high RBE than cells & tissues w/small shoulders
dose rate most dramatic at what dose rate?
most dramatic b/n 1-100 cGy/min
high LET exhibits ? dose rate effect
high LET does NOT show dose rate effect
nitroimidazoles mimic
O2
halogenated pyrimidines substitute ?
substitute for base thymidine in DNA
radiation protectors reduce dose by factor of
1.5-2
biological factors (2)
- cell cycle (G, S, G2, M)
- intracellular repair (SLD, PLD)
acute effects have ? a/B ratio
high
late effects have ? a/B ratio
low
structural tissue tolerance
parallel organiz, serial organiz
parallel organization shows pronounced
volume effect (lung)
serial organization shows little
volume effect (spinal cord)
as dose rate decreases cell killing ?
increases= b/c cells continue to progress thru cell cycle & become arrested in G2 phase
acute effect causes depletion of ? cells
parenchymal cells
healing is fxn of ?
dose & organ irradiation
repair
- replacement by diff cells
- only after high doses so regen not poss
hemopoietic system made up of
bone marrow, circulating blood, lymphoid organs
liver rad hepatitis dose
35-45Gy
dose lungs respond to
> 10Gy
radiation nephritis due to
loss of tubules
which part of spine most sensitive
c & t spine more sensitive than L
LD 50/30 rad syndrome whole body irrad dose
450 rad (cGy)
hemopoietic syndrome dose
1-10 Gy
GI system syndrome dose
10-100Gy
CNS system syndrome dose
> 100Gy
russell & russell developed what
stages of fetal development
greatest variety of congenital abnormalities happen when?
23-37 day
fetus most sensitive at what time?
1st 6 wks
linear model assumes
risk per rad same @ low doses as high
committed dose is
exposure is from radionuclide
spontaneous abortion dose/time frame
10rad (0.10Gy) during 1st 6 wks
cell loss carcinoma vs sarcoma
carcinoma shows > cell loss than sarcoma
tumor growth balance of 3 factors
1=cell cycle time
2= growth fx
3= cell loss
hyperthermia best in what cell phase
S phase sensitive to heat
mean latent time for appearance of all rad-induced CA
25 yrs
mean survival time meaning
avg time b/n lethality & death
spontaneous abortion dose & time during pregnancy
exposure 50-200 cGy to fetus in 1st trimester
dose response relationship y axis is ?
response
TER stands for
thermal enhancement ratio
RBE stands for
relative biological effectiveness
early effects dependency total dose is ?
total dose = high
late effects dependency total dose is ?
total dose= high
therapeutic ratio
normal tissue tolerance dose/tumor lethal dose
deterministic effect aka ?
non-stochastic effect
stochastic effect limited to what effects?
ca & genetic effects
abnormal cell proliferation occurs when
differentiation is disrupted
protoplasm is made mostly of
70-85% H2O
nucleus houses
DNA & RNA
alpha (a) killing
single hit killing
alpha (a) repair?
no repair
alpha (a) curve shape
steep curve
beta (B) events
2 separate events
beta (B) repair?
chance of repair
beta (B) curve shape
shallow curve
norm tissue typical value/dose of a/B - early effects
10Gy
radiation interaction occurs
rapidly
radiation interaction selective?
nonselective
radiation interaction damage looks like?
no different than if produced by trauma
radiation interaction damage occurs after
latent period
direct interaction probability occurs more with ? LET
high LET
direct interaction probability %
25
Puck & Marcus curve type
1st mammalian cell curve
Mammalian cell survival curve x-axis
linear
Mammalian cell survival curve y-axis
log
Mammalian cell survival curve relationship
b/n radiation dose & cell survival
Mammalian cell survival curve fxn
cell kill exponential fxn of dose
N of cell survival curve #
b/n 2-10 = target #
Dq intercepts ? on cell survival curve
Do @ 100% survival
Dq dose
quasi-threshold dose
Do % die on cell survival curve
63% die
high dose curve sensitivity
less sensitive
low LET on cell survival-repair?
yes- will repair
high LET on cell survival curve- repair?
no
fate of rad cells during division
interphase death
fate of radiated cells during division
reproductive failure
indirect interaction produces
free radicals with H2O
indirect interaction occurs ?%
75
free radicals produce
ion pair OH & H
free radical rxn toxic
join other free rad to make H2O2
free radical rxn combine with norm compound
form new free rad
LET unit
keV/micrometer
EMR charge
no charge
EMR speed
- speed of light
- 3 x 10^8 m/s
- 3 X 10^10 cm/s
RBE formula
dose of std radiation (250 keV)/dose another radiation
does single strand break on chromosome repair?
yes, usually repairs
division delay happens in
G2 & S phase
interphase death undiff cells
occurs at lower doses
interphase death dependent on
dose
reproductive failure occurs at what dose
> 10Gy
reproductive failure is dependent on
dose
SLD repair occurs
when 2 doses separated by time
SLD repair happens unless
another dose given
SLD repair larger when
2 separate doses than with 1 large dose
PLD repair type of radiation
only low LET radiation
PLD repair demonstrated after
1 dose radiation
Bergonie & Tribondeau dividing cell
actively dividing
Bergonie & Tribondeau cell diff
undiff
Bergonie & Tribondeau dividing future
long dividing future
appearance radiation damage influenced by ? conditions
conditions to which cells exposed pre & post irrad
stem cell examples
- basal
- bone marrow
- crypts of Lieberkuhn
- spermatogonia
static cell differentiation
fully differentiated
static cell examples (2)
- adult nerve cell
- adult muscle
VIM cell characteristics
rapidly dividing, undiff, short life
VIM sensitivity
MOST sensitive
VIM cell examples
- skin basal
- crypt cell
- type A spermatogonia
- erythroblasts
RBE incr as dose per fx ?
decr
OER value
2.5
OER less after ? doses
low
OER more pronounced with ? radiation
low LET
nitroimidazoles examples
- miso
- SR2058
- R003 8799
halogenated pyrimidines sensitize cell by factor of
2
sulfhydryl group is a radiation ?
protector
W2721 is a radiation ?
protector
radiation protectors used in ? treatments
intra-op & TBI
hemorrhage is ? change
acute
sebaceous & sweat glands sensitivity
radioresistant
eye dose cataracts single dose
4Gy
telegiectasia
small dilated blood vessels
sclerosis
hardening of tissue
both kidneys shielded to total dose of
26 Gy
fatal nephritis dose
28Gy in 5 wks to both kidneys
exclusion of ?/3 greatly minimizes kidney failure
1/3
preimplantation time frame
conception to 10 days
organogenesis time frame
10 days to 6 weeks
fetal time frame
6 weeks to growth
committed dose equivalent time frame
50 yrs following intake of radionuclide (working life of individual)
hyperfractionation increases ? over same time
total dose
hyperfractionation fraction size is
doubled
hyperfractionation total dose incr/decr
incr
hyperfractionation spares what kind of tissue
late responding by decreasing size of dose per fx
hyperfractionation associated with ? effects
acute
accelerated fx dose pattern
- reduces overall duration w/o significant chg in size of dose/fx or total dose
- 2 times a day
accelerated is associated with
increased acute effects
hyperthermia kills at low ?
pH
hyperthermia inhibits repair of
DNA (SLD/PLD)
hyperthermia temp/duration
41-45C (106-113F) for 30-60 min
hyperthermia formula
w/o heat divided by w/heat
dose response relationship x- axis is ?
dose in Gy
TER formula
ratio of dose w/o heat divided by w/heat for given effect
RBE formula
ratio of standard 250 keV divided by given dose of other quality radiation
early effects dependency time is ?
high
early effects dependency dose per fx is ?
low
late effects dependency time is ?
low
late effects dependency dose per fx is?
high
deterministic effects is defined as
somatic effect that increases in severity as a rad dose increases above dose threshold
stochastic effect is ? induced injury
radiation
stochastic effect is ? effect
all or nothing
OER for photon/electron therapy is
2.5-3
