*** 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