RadBio

what does the shoulder of the cell survival curve represent?

• where cells can repair and are capable of surviving

• reduction in efficacy of cell-killing at low doses

what is the Dq of the cell survival curve?

• the side/width of the shoulder (quasi-threshold)

• sublethal dose: dose at which survival becomes exponential

what is the Do of the cell survival curve?

• the dose that reduces surviving fraction to 37%

What is the Law of Bergonie and Tribondeau?

• states that cells are most sensitive when they are actively mitotic, undifferentiated, and have a long mitotic future

When in the cell cycle are cells most sensitive and most radioresistant?

• most sensitive:

• M → G2 → G1 → S

what are the 4 Rs of radbio?

• repair: of DNA damage

• redistribution: of cells in cell cycle

• repopulation

• reoxygenation: of hypoxic tumor area

What is the oxygen enhancement ratio?

• a well-oxygenated tumor is more radiosensitive than a poorly oxygenated tumor

When are radiation effects more severe for a fetus?

• 3-12 weeks post fertilization

• think organ formation

what is the biologically effective dose (BEDs)?

• measure of the biological effect of radiation to tissue, accounting for changes in dose per fraction, total dose, and overall time

• its how fractionation works

• always need to be considered in retreatment

what is biological equivalent dose?

• reports equivalent dose needed in 2Gy/fx to achieve BED