Ch4 Cell Kill and Survival Flashcards
Tumor growth occurs when
not all neoplastic stem cells are killed
Survival curves
- Raltionship between
- What is random?
- ___ function of dose
- Rad dose and amount of cells that survive
- Location of deposited energy
- Exponential
Cells are killed by ___
Chance
What is “saturation”
Accumulation of damage per each cell
Cell kill
- Is not a ___ phenomena
- Reffered to as
- 1 to 1
- Exponential
Cell survival curve is a ___ graph
Semi-logarithmic
On a cell survival cuve
- x-axis stands for
- y-axis stands for
- Dose
- Surviving fraction of cells plotted
A cell survival curve is showing the
relation of survival/death and dose used to kill
Depicted by a shoulder followed by a curve that identifies at
what does there is zero cell survival
Indicates cell sensitivity!!
Target theory (killing mechanism)
- states that
There are “N” targets in a cell which must be hit to kill it. But If one target is missed the cell will survive.
Target theory
- N stands for
- N-1 stands for
- number of targets or DNA in a cell needed to be hit in order to produce cell kill
- Population has only one target in each cell that must be hit to be killed (All but one target have been killed, “Threshold dose”
N number in humans range from
2-10
Dq or quasi stands for ___ dose
Threshold dose
Do stands for ___ dose
Terminal slope dose
Do
- The dose that kill ___% of population
- Represents
- 37%
- Cell survival
Do
- Shallow curve represents
- Steep curve represents
- Radioresistant
- Radiosensitive
Dq
- defines on a graph
- represents
- Width of the shoulder region
- cells ability to accumulate and reapir sublethal damage
Do in mammalian cells is ___
1-2 Gy
Sublethal damage (SLD) occurs when
two doses are seperated by time
SLD
- One more dose is given to DNA
- No more doses are given DNA
- It Dies
- Is Repaired
Sublethal damage relates with a cells
Ability to repair
SLD fractionation promotes
repair
If full dose is delivered at once what would not be possible
Repair
Potentially Lethal Damage (PLD) occurs when
post irradiated conditions are modified
Cell death most likely to occur in which condition
optimal nutritional conditions, because the cell can divide
Cell death is less likely in sub optimal conditions because
Cells are in hibernation and have to repair the damage and wont divide
cell death is seen as the
decrease in the number of cells that can reproduce
