RAD BIO test 2 Flashcards
what does LD x/y stand for?
LD= lethal dose
x= percentage of population
y== number of days it is measured
(how much lethal dose and how many days it will take to kill the population, LD 50/30)
what are the orders for cell phases?
prophase
metaphase
anaphase
telophase
what is dose response?
linear non-threshold assumes that any dose of radiation can cause damage
most late effects follow this dose response
what is the most radiosensitive phase of a cell?
mitosis (division)
what is Dose rate?
what happens to effect if dose rate goes up?
how quickly a dose is delivered
dose rate goes up, effect increases
what is the law of Bergonie & Tribondeau?
Like?
cells are more sensitive if they are more primitive & prolific (lymphocytes)
what is protraction?
if protraction goes up, what happens to effect?
how slowly a dose is delivered
protraction increases, effect decreases
what is the most radioresistant cell phase?
mid to late S phase (DNA replication)
what is interphase cell death?
several hundred Gray can kill a cell before it can divide
what are somatic effects?
what two ways can this be measured in?
systemic effects of radiation to an individual
deterministic & stochastic
what is deterministic?
biological effects that can be directly related to the dose received
threshold dose
occurs after a large dose of radiation
can occur in fluroscopy
what is fractionation?
what happens to effect if fractionation increases?
delivering dose in discrete portions with a recovery period in between
fractionation increases effect deceases (90% repairable)
what are deterministic early effects?
later effects?
Erythema (2Gy), epilation, infertility
(hours/days/weeks 90% repairable)
cataracts, temporary sterility (100 mSv)
what are stochastic effects?
what type of effects?
randomly occurring biological effects of radiation
non-threshold
can happen in radiology (unlikely) probability increases with dose
late effect (cancer/ genetic abnormalities)
what are teratogenic effects?
What are the by products of this?
occurs en-utero to a developing embryo or fetus
Congenital abnormalities, skeletal defects, & leukemia
skeletal defects result during exposure at:
3rd week of gestation
A ___ ____ embryo is ____ ____more sensitive to radiation than an adult
10-day
10 times
how much of the skin exposure of the mother does the fetus recieve?
1/3 (for abdomen)
Leukemia results from exposure during:
mid-to late fetal growth
Congenital abnormalities are likely caused by:
radiation (exposure) at 2-8 weeks
Leukemia results from exposure during ___
mid-to late fetal growth
skeletal defects result during exposure at:
3rd week of gestation
how much of the mothers skin dose does a fetus receive on an abdomen x-ray?
1/3
A ____ day embryo is ___ times more sensitive to radiation than an adult
10
10
Genetic code consists of what?
a sequence of nitrogenous bases found in the DNA
how many pairs of chromosomes are there?
23 pairs
Transfer RNA (tRNA) is attached to a specific ___
amino acid
what is target theory?
certain molecules are critical to the survival of a cell
what is direct effects?
Example?
x-ray photon deactivates a target molecule
(x-ray photon directly damages a key gene of a chromosome)
(deactivation of a target molecule from an x-ray photon)
what is indirect effect?
What is most affected?
radiation ionizes water which in turn deactivates a target molecule
most damage caused by this effect (cytoplasm of the cell)
what is a free radical?
any uncharged atom with a single unpaired electron in its outermost shell
what can be the end result of hydrolysis (radiation) of water?
hydrogen peroxide
what is the oxygen effect?
What kind of hits?
tissue is more sensitive to radiation when irradiated in an oxygen rich environment
(indirect hits)
what is acute radiation syndrome?
“radiation sickness”
occurs after large doses of radiation over a short period of time
What are the 4 stages of acute radiation syndrome?
prodromal
latent
manifest illness
death
Prodromal:
side effects?
ARS within hours
nausea, vomiting, diarrhea, & fatigue
Latent:
symptoms?
1 week
no symptoms, false sense of recovery
manifest illness:
less than 1 week
syndrome effects
death:
instant or in some cases recovery with long-term effects/damage
what are the 3 main symptoms/syndromes?
hematopoietic
gastrointestinal
cerebrovascular
Hematopoietic syndrome:
range?
death?
effects?
who suffered early on?
1-10Gy
death in 6-8 weeks
decreased blood cells in bone marrow & body is susceptible to organ failure/infection
early radiologists suffered from leukemia
what are the gastrointestinal sydromes:
6-10 Gy
death in 4-10 days
damage to epithelial cells that line the GI tract (inability to absorb nutrients)
dehydration & severe diarrhea
what is the cerebrovascular syndrome?
range?
death?
effects?
50Gy+
death in hours to 3 days
fluid leaks into brain and intracranial pressure + central nervous system failure
what does LET stand for?
what is it?
linear energy transfer
the amount of energy deposited by radiation into a material per unit path or length
what is high LET?
high LET=
Example?
is low penetration (alpha particles) & high RBE
Alpha particles
what kind of LET has high penetration?
low LET
(Gamma & x-ray’s)
low LET is associated with:
single strand DNA breaks
linear energy transfer of x-ray is low due to ___ ____
high penetration
High LET=
Low LET=
low penetration (alpha particles)
high penetration (gamma & x-ray)
