L 6: O2 effect and RE-O2 Flashcards
1
Q
Rapidly growing cells in vitro
A
smaller OER
2.5 at lower doses
2
Q
Variation of OER with cell cycle
A
G1 Phase: Lower OER than S
As G1 phase cells are more radiosensitive.
3
Q
OER
O2 enhancement ratio
A
The ratio of doses under hypoxic to aerated conditions necessary to produce the same level of killing.
Normal value is close to 3.5
4
Q
How does O2 work?
A
Damage produced by free radicals in DNA can be repaired under hypoxia but the damage is made permanent or irreparable in presence of O2.
5
Q
RT sensitivity in presence of O2
A
3 times more sensitive
6
Q
Acute Hypoxia
A
7
Q
Chronic Hypoxia
A
This is due to teh distance of tumor cells from the blood vessels
