Weekly quiz questions Flashcards
Are low (<0.01Gy/min) or higher dose rates (>1Gy/min) more effective at cell kill?
Higher dose rates are more effective at cell kill
DNA damage is the biological effect of radiation for which level of study?
Molecular Level
The inhibition of cell division is the biological effect of radiation for which level of study?
Cellular Level
Death is the biological effect of radiation for which level of study?
Whole animal
Genetic is the biological effect of radiation for which level of study?
Population
What are the possible outcomes of cell damage due to radiation?
- the cell might incorrectly repair itself (mutate/ modified cell)
- Injured or damaged cells may repair themselves through the body’s defence mechanisms, resulting in no residual damage
- The cell may die
Lesions in the DNA occur at which phase?
chemical phase
What are possible DNA damages that results from radiation?
base damage
intercalation
cross links
point lesions
What are possible cell damages that result from radiation?
interruption of the cell’s food supply
membrane rupture
damage to lysosomes
damage to the nucleus and DNA
What type of strand break occurs most often?
single
“the greatest amount of strand breaks in DNA is ____ strand breaks”
Which form of oxygen are involved in the oxygen enhancement effect?
elemental oxygen within the cell
Tumours which have areas of hypoxic cells and therefore more difficult to control with low LET ionising radiation are called?
radio resistant
Which effect (indirect or direct) is the most important mechanism in causing damage from low LET radiation?
the indirect effect is the most important as it causes about 2/3 of the total damage
Graphs of cell sensitivity versus phase of the cell cycle are called?
Age response curves
The cell survival curve has several mathematical models which provide possible descriptions. One models assumes that each cell needs to be hit once only to cause reproductive death. This model is called?
single-sarge, single-hit model
Three possible mathematical descriptions of the cell survival curve are?
single-target, single-hit model
Multitarget, single-hit model
the linear-quadratic model
What is the effect that: when a free radical is formed within a cell and goes on to damage the DNA?
this is called the indirect effect
Which deterministic effects following whole body irradiation is most likely to be successfully treated with antibiotics and/or bone marrow transplants?
Hematopoietic syndrome resulting from 3-8 Gy may be treated with antiobiotics and/or bone marrow transplants. Without such treatment death will occur in 3-8 weeks.
What are the known causes for the reduction of the number of circulating blood cells in relation to the Haemotopoietic syndrome?
loss by haemorrhage
direct destruction of circulating white blood cells
With the cerebrovascular syndrome, much higher doses are required to produce death when just the head is irradiation as opposed to a whole boy irradiation. True or False?
True
Do deterministic effects have a threshold (i.e. are they observed with even the smallest of doses?)
There is a dose threshold for deterministic effects, below which no effect is observed.
The phenomenon that radiation effects are less pronounced in some cells that have received a prior radiation dose is called?
Adaptive response
According to ICRP60, which dose rates are most likely to cause permanent sterility in women?
a single dose of 2.5Gy
a prolonged dose of 0.2 Gy per year
A group of cells is irradiated by shows no effect. Several generations later, effects do start to show up. This phenomenon is called?
Genomic instability
What are the two known possible effects of the Gastrointestinal syndrome?
electrolyte imbalance
problems with absorption of metabolites
Which doses are most likely to cause permanent sterility in men according to ICRP60?
single dose of 3.5 Gy
prolonged dose of @ Gy per year
You have a dish full of cels and irradiation on half of the dish. You then observe that some of the cells in the unirradiated half behave as if they have been irradiated. This phenomenon is called?
The bystander effect
How can you treat Hematopoietic syndrome?
hematopoietic syndrom resulting from 3-8 Gy may be treated with antibiotics and/or bone marrow transplants
What is the adaptive response?
radiation effects are less pronounced in some cells that have received a prior radiation dose
What is genomic instability?
a group of cells is irradiated but shows no effect, until several generations later
What is the bystander effect?
half the non-irradiated cells behave as if they have been irradiated.
Regarding Watch Dial Painters, or Radium Girls, which three symptoms did they initially percent with?
teeth falling out
tumours and fractures of the jaw
anaemia
In the study of Japanese atomic bomb survivors, what were three reported early symptoms of radiation exposure?
vomiting
hard loss
bleeding from the gums
Why are doses from the Hiroshima atomic bomb more difficult to determine than the Nagasaki atomic bomb?
The bomb dropped on Hiroshima was a cannon type of bomb so the explosion was not symmetrical, whereas the Nagasaki bomb was an implosion device with a spherical explosion.
What were three means of exposure for early uranium miners?
external exposure by gamma rays
exposure to short live radon gas and it’s radioactive daughters
inhalation of dust and it’s long lived radionuclides
List two features of stochastic effects.
They show up as mutations
They are random in nature
Which three statements contribute to the debate about whether the Linear No Threshold model is correct?
- The LNT model is based on doses in the range of about 0.2Sv to 5Sv
- Th doses received in medical imaging and by workers is much less than the actually measured so these workers can’t be used in the estimates
- To estimate risks for low doses (<100mSv), the information has to be extrapolated from higher doses, and the extrapolation has many uncertainties.
What is the total risk of death from exposure to ionising radiation (low dose/ low dose rate) for the general population (per million exposed to 10mSv)
The total risk for the general population is 500 per million exposed to 10mSv
Based on studies of Bohemian Uranium miners from the early 1900s, what is the risk estimate from lung cancer (per million people exposed to 10mSv)?
the risk is 85 per million exposed to 10mSv
Regarding stochastic effects, if you increase the radiation dose this will?
increase the probability that an effect will occur
What are the two objectives of radiant protection, in regards to deterministic and stochastic effects?
reduction of the probability of occurrence of stochastic effects
prevention of determinist effects
Based on studies of atomic bomb survivors, Marshall Island nuclear testing survivors and radiotherapy patients, which are two known risk estimates for induction of thyroid cancer?
50-150 cases induced per million people exposed to 10mSv
8 feathers per million exposed to 10mSv
What is the total risk of death from exposure to ionising radiation (low dose/ low dose rate) for radiation workers (per million people exposed to 10mSv)?
Fro radiation workers the risk is 400 per million exposed to 10mSv
Are radiation induced cancer indistinguishable from any other type of cancer?
yes, you can’t distinguish between radiation and non-radiation induced cancers
Which studies contributes to our knowledge of stochastic effects?
studies of radiotherapy patients
the lifespan study of atomic bomb survivors
workers in uranium mining
Data measuring children of atomic bomb survivors show definite increases in the risk of congenital abnormalities, cancer, and chromosome aberrations. (true or false)
false
There are simply not the statistics to show that any of the named conditions in children of atomic bomb survivors
In the Megamouse experiment, the rate of induction of mutations varies by up to a factor of _______ between the 7 loci studied
here is a variation in mutation rates by a factor of 35 between the 7 loci studied, indicating that different gene loci have different radiosensitivy
What are three possible effects of radiation exposure during the organogenesis stage (10 days to 6 weeks)?
malformation of organs
small head
intrauterine growth retardation
In humans, what is the assumed safety period for the time between irradiation and conception (in months)
6 months
During the organogenesis stage of pregnancey (10 days to 6 weeks), what is the LD50/30 in Gy?
LD50/30 is 1.5Gy during organogenesis
What is the risk estimate for childhood cancer (under 10 years) for those exposed to radiation in-utero?
the risk is 200-250 per million exposed to 10mSv
What are two known possible effects of radiation exposure during the development of an embryo?
pre and neo-natal death
growth retardation
For protracted exposure, radiological life shortening is?
<1% per Sv
True or False?
The Megamous experiment has shown that at low dose rates, males are more sensitive to genetic damage than females..
True
What is the annual radiation dose (in mSv) you receive from internal radiation sources (i.e. the radioactive atoms inside your body)?
0.4mSv
According to the lecture slides, which value falls within the average range of annual occupational dose in Australia for radiotherapists (RT)?
0.7mSv
range of 0.5mSv to 1mSv
Which three industries have a higher fatality rate per million workers per year than radiation workers?
deep sea fishing
construction
coal mining
How many minutes canoeing gives the same (one in a million) risk of fatality as 20 uSv of radiation?
6 minutes
What is the average annual dose (in mSv) you receive from cosmic rays?
0.3
According to the lecture slides, what is the risk of contracting a fatal condition due to radiation exposure for the general public? (number per million per 10 mSV).
500
According to the lecture slides, which of the following is within the average range for the average annual occupational exposure for radiographers (MITs)?
0.15mSv
True or false? The magnitude of theoxygen enhancement effect is much less for high LET radiation such as alpha particles, than it is for low LET radiation such as x-rays.
True
The cell survival curve has several mathematical models which provide possible descriptions. One model assumes that there are two components to cell killing, one due to single event killing and one due to two event killing. This model is called:
linear quadratic model
In a group of cells, if 68 % are killed by a radiation dose in the presence of oxygen, and 36 % are killed by the same radiation dose but in a hypoxic environment, what is the oxygen enhancement ratio? (1 decimal place).
1.9
(68/36)
(oxygen/hypoxic)
Which of the following processes are not a part of the biological phase?
apoptosis
formation of radicals
mitotic death
carcinogenisis
“The number of _______ strand breaks in DNA correlates best with cell kill”
double
A whole body irradiation of 1000Gy, 100Gy, 10-100Gy and 2-10Gy, results in death after how many days?
1000Gy: immediate
100Gy: 1-2 days
10-100Gy: 3-10 days
2-10Gy: 10-60 days
“In relation to the Haematopoietic syndrome, recovery is possible for doses less than ____ Gy and with no medical support.”
4Gy
With the Cerebrovascular syndrome, death appears to be a result of an elevated fluid content of the brain. (true or false)?
true
One aspect of studies of atomic bomb survivors is the study of those who were in-utero at the time of the exposure. In this study, mental retardation is most pronounced for what timeframe of exposure?
8-15 weeks after conception
What is the risk estimate fordeaths due to bone cancer(the number per million peopleexposed to 10 mSv).
The risk estimate for fatal bone cancer is 5 per million people exposed to 10 mSv.
What are possiblealternativesto the Linear No Threshold model for stochastic radiation effects?
threshold and hormetic relationship
downwardly curving
upwardly curving
What is the estimate of risk offatal leukaemiafrom exposure to thebone marrow(give the number, per million people exposed to 10 mSv).
The best risk estimate for fatal leukaemia after exposure of the bone marrow is 50 per million people exposed to 10 mSv.
According to thelinear no threshold model, at 0 Gy there is what chance that a person would develop a radiation induced cancer?
0
Based on studies of Bohemian Uranium miners from the early 1900s, what is the risk estimate for lung cancer (per million people exposed to 10 mSv).
85 per million exposed to 10 mSv.
What is the risk estimate for breast cancer casesper million people exposed to 10 mSv?
The risk estimate is 20 cases per million people exposed to 10 mSv.
What is the total risk of death from exposure to ionizing radiation (low dose/low dose rate) forradiation workers(per million people exposed to 10 mSv)?
400
What arethreeresults of animal studies of the genetic effects of ionizing radiation?
Results of animal studies show that there is:
no threshold
there is a dose/effect relationship
and there is no effect of fractionation
What is thedoubling dosein man (in Gy)?
The doubling dose in man is 3 Gy
What is the risk estimate for childhood cancer (under 10 years) for those exposed to radiation in-utero?
The risk is 200-250 per million exposed to 10 mSv.
What is the likely threshold (in Gy) for mental retardation due to in-utero radiation exposure?
The likely threshold for mental retardation is about 0.2 Gy for in-utero radiation expousre (it is a deterministic effect).
During thepre-implantationstage of pregnancy (0-9 days after conception), the most significant risk from radiation exposure is:
Neo-natal death is the most significant risk during the pre-implantation stage of pregnancy.
Foracuteexposure, radiological life shortening is: (%??)
Radiological life shortening is of the order of 1-5% per Sv for acute exposure
According to the lecture slide, what is the average risk for contracting a fatal cancer due tooccupational radiation exposure(the number per million per 10 mSV)?
The annual risk is 400/million.
A CT scan of the head is equivalent to how manyyearsof normal background radiation?
It’s equivalent to 1.4 years of normal background radiation.
Eating how many tablespoons of peanut butter gives you a one in a million chance of fatality?
40
How manydaysof normal background radiation gives the same radiationdose as a Chest PA x-ray?
3
What is the annual radiation dose (in mSv)you receive from internal radiation sources (i.e. the radioactive atoms inside your body)?
0.4mSv
For an occupation to be considered as having an acceptable level of risk (or high level of safety), what is the annual mortality risk? (number per million).
A safe occupation has an annual mortality risk of about 100 per million.
The D37 Dose is the dose for which survival (S) is 37% and is used to indicate the ______ of the cell line.
radiosensitivity
Double strand breaks require a break in both strands of the DNA, about ____nm apart.
2nm
What are four effects that relate to the gastrointestinal syndrome?
infection
fluid loss
electrolyte imbalance
problems with absorption of metabolites
Based on studies of atomic bomb survivors, marshall island nuclear testing survivors and radiotherapy patient, what are two known risk estimates for induction of thyroid cancer?
8 deaths per million people exposed to 10mSv
50-150 cases induced per million people exposed to 10mSv
What are three statements that contribute to the debate about whether the linear no threshold model is correct?
to estimate risks for low doses, in information has to be extrapolated from higher doses, and the extrapolation has many uncertainties
the doses received in medical imaging and by workers is much less than the ranges actually measured so these workers can’t be used in the estimates
the LNT modle is based on doses in the range of about 0.2Sv to 5Sv
What is the risk estimate for deaths due to bone cancer (the number per million people exposed to 10mSv)
5
What is the risk estimate for fatal leukaemia from exposure to the bone marrow (the number per million people exposed to 10mSv)
50
