Irradiation hits occur through:
Direct and Indirect effects
According to target theory, the target molecule of a cell is:
the DNA in the nucleus
A target molecule that is what will always cause cell death?
inactivated
A hit to a cell target can occur from what effect?
Direct or Indirect
The probability of a hit increases the greatest with _______ oxygen and ________ LET radiation.
High, Low
The lethal effects of cell irradiation are measured by cell:
Survival
The _____-target, _______-hit model of radiation induced cell death applies to simple cells only.
Single, Single
The DO represents the _______ dose for human cells.
mean lethal
Human cells are most radiosensitive during the ________phase of the cell cycle.
Mitosis
The DQ is the _______ dose for irradiation of human cells.
Threshold
What type of radioactive particle has the highest LET?
Alpha Particles
The mean lethal dose for high LET radiation is ________than after low LET radiation.
Lower
If oxygen is present during low LET radiation, the effect of radiation is?
Maximal
If oxygen is present during high LET radiation, the effect of radiation is?
The Same
The x-intercept of a low LET cell-survival curve is _____than a similar high LET cell-survival curve.
Larger
With low LET, anoxic conditions _______ probability of a hit
decrease
With low LET, aerobic conditions _______ probability of a hit
increase
With high LET, OER is ________
negligible
With high LET, the probability of a direct hit is _________
increased
Indirect hit
hits water or other molecule that is not DNA and transfers the energy to DNA
Direct hit
the hit happens directly to the target molecule (DNA)
The cell must be _______ to cause cell death
inactivated
The lethal effects of radiation are determined by observing cell ________, not cell death
survival
How many days does it take to repopulate colonies?
10-14 days
_______ dose decreases the number of colonies of cells repopulating
increasing
The single target, single hit model applies to _________ organisms
single-celled
What is the Poisson distribution?
the statistical law that governs the probability of a cell being hit. It states that when the # of photons = the # of cells, 63% of the cells will be hit and 37% will not
According to the Poisson distribution, as the # of photons ________, the more cells will be hit
increases
D37
the radiation dose reaches a level sufficient to kill 67% of the cells or there is 37% cell survival
A low D37 = highly ___________ cell
radiosensitive
A high D37 = ________ cell
radioresistant
For the multi-target, single-hit model, both sides of the cell must be hit before it is _________
inactivated
As the radiation dose ________, fewer cells survive because more sustain a hit in both target molecules
increases
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