Dose And Damage PPT Flashcards
What is TD 5/5?
TD 5/5 is the dose that results in minimum (5%) of severe complications within 5 years post treatment.
What is TD 50/5?
TD 50/5 is the dose that results in maximum (50%) of severe complications within 5 years post treatment.
What factors does TD 5/5 depend on?
TD 5/5 depends on the volume of the organ irradiated, the nature of the organ, and the dose tissue is receiving.
What happens when you increase the volume of the organ irradiated?
When you increase the volume of the organ irradiated, the total dose must be lowered to avoid unacceptable complications.
What is the common practice among oncologists regarding TD 5/5?
Most oncologists will not exceed TD 5/5 for normal structures or TD 50/5 for the targeted tumor tissues.
What is a possible outcome of cell irradiation with no effect?
No effect.
What happens during division delay in irradiated cells?
Cell is delayed in going through division.
What is apoptosis in the context of cell irradiation?
Cell dies before it can divide.
What is reproductive failure (mitotic death)?
Cell dies when attempting mitosis.
What does genomic instability refer to?
There is a delay in reproductive failure.
What is a mutation in irradiated cells?
Cell survives but contains a mutation.
What is transformation in the context of mutations?
Mutation leads to a transformed phenotype and possibly carcinogenesis.
What are bystander effects?
Irradiated cell may send signals to neighboring unirradiated cells and induce genetic damage in them.
What are adaptive responses in irradiated cells?
Irradiated cell becomes more radio-resistant.
What does a survival curve describe?
A survival curve describes the relationship between radiation dose and proportion of cells that survive.
How is the radiation dose distributed to the cells?
The radiation dose is distributed to the cells randomly.
What are the possible outcomes for cells when exposed to radiation?
Some cells will receive one hit, some cells will receive more than one hit, and some cells will not be hit at all.
What is the shape of the survival curve for mammalian cells exposed to X and Y rays?
The shape of the curve has a shoulder, followed by a steep, straight portion.
What is a Cell Survival Curve?
A graphical representation of the fraction of surviving cells as a function of dose.
What does the Extrapolation Number or Hit Number measure? (n)
It measures the shoulder width of the survival curve.
What does a large n indicate in a Cell Survival Curve?
A broad shoulder.
What does a small n indicate in a Cell Survival Curve?
A narrow shoulder.
What is the Quasi-Threshold dose? (Dq)
It is a dose below which there is no effect.
What does a large Dq represent?
A broad shoulder in the survival curve.
