Final exam select topics-radiotoxicity Flashcards
what is ionizing radiation
radiation with sufficient energy to displace electrons from molecules
what are 2 types of ionizing radiation
particles and electromagnetic waves (photons)
what are 4 examples of particle radiation
alpha beta protons neutrons
what are 2 examples of electromagnetic waves
x and gamma
order alpha gamma neutron x rays and b particles for least to most penetration
alpha
which of alpha beta gamma x are charged
alpha beta
which of alpha beta gamma x are uncharged
x gamma
which of alpha beta gamma x are zero mass
x gamma
how do photons (x gamma) cause ionization
transfer energy to electrons which become energetic and are released (indirectly)
how do charged particles ( b a ) cause ionization
directly collide with electrons of atoms
what is the berequel
basic unit of radiation activity, 1nuclear disintegration/second
what is gray
basic unit of dose, J released/ kg tissue
what is LET
average energy lost from a charged particle per unit length of trajectory
which of alpha beta gamma x are low LET
gamma x b
which of alpha beta gamma x are high LET
alpha and neutrons
what is created when ionizing radiation passes through matter
ion pais (electron and +ve atom residue)
what can ionizing radiation do to DNA
ds and ss breaks
what are the 3 kinds of doses ( in order )
absorbed, equivalent, effective
what is absorbed dose (units + definition)
gray (J/kg), energy absorbed by target
what is equivalent dose (units + definition)
sievert (J/kg), biological effect that depends on radiation type
what is effective dose (units + definition)
sievert (J/kg), biological effect on tissue type
how do you go from absorbed dose to equivalent dose
Wr (radiation weighing factor)
how do you go from equivalent dose to effective dose
Wt (tissue weighing factor)
what is the formula for equivalent dose
summation of : Wr (radiation weighing factor) x absorbed dose for each radiation type (DT)
what is the formula for effective dose
summation of : Wt (tissue weighing factor) x equivalent dose for each radiation type (HT)
what does low LET mean for amount of ionization
only few will be made
what does high LET mean for amount of ionization
thousands
what does low LET mean for location of ionization
in isolated places/ spread out
what does high LET mean for location of ionization
all in once cluster
what are the 3 components of the DNA damage response
sensors, transducers and effectors
what do the sensors do
alert and amplify damage signal to transducers
what do transducers do
signal damage further to downstream effector proteins
what do effectors do
lead to cell cycle arrest, apoptosis or repair
how can we measure DNA damage using assays
use antibodies to gammaH2AX which is a sensor protein for dsDNA breaks
what is gammaH2AX
sensor protein for dsDNA breaks
what can happen to chromosomes with radiation
translocation (fusions)
how can chromosomal translocations happen with radiation
decrease in telomere repair mechanism or loss of telomeres from ds break (uncappted chromosomes more likely to go through rearrangements)
what is hormesis
low doses of radiation can push subsequent DNA damage to below background levels
what is the main model of risk (graph) that is accepted (like radiation dose vs risk)
LNT - linear non threshold, straight line (constantly exposed to radiation so its hard to know if theres a threshold)
what were the main isotops from chernobyl
131 I, 137 and 134 cesium
what was the main type of issue chernobyl survivors faced
thyroid cancer
what are 4 stages of radiation sickness
- prodormal (nausea vomit)
- latent (better)
- illness ( weeks later, CNS disorders, CV and pump issues, bone marrow destruction, cutaneous syndrome-blisters hair loss ulcers)
- recovery or death
what may be the antidote to radiation maybe
DTPA - zinc or calcium conjugates
how does DTPA work
exchanges its calcium or zine for radionucleotides
