Flashcards on The R's of Radiotherapy: Radiobiological Principles
The R's of Radiotherapy: Radiobiological Principles Explained
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Radiobiology
58 cards
Card 1
Question: What are the classic 4 R's of radiotherapy?
Answer: Recovery from sublethal damage; Redistribution within the cell cycle; Reoxygenation of the tumor; Repopulation of cells.
Card 2
Question: What additional R is included to make the 5 R's of radiotherapy?
Answer: Radiosensitivity.
Card 3
Question: What two extra R's are listed in the 6 R's of radiotherapy in the content?
Answer: Radiosensitivity and Reactivation of the immune response.
Card 4
Question: What does 'recovery from potentially lethal damage' refer to in radiobiology experiments?
Answer: Enhanced cell survival when irradiated cells or tumors are left a period of time before plating or removal, allowing repair of potentially lethal dama
Card 5
Question: How was recovery from potentially lethal damage demonstrated experimentally in the provided figures?
Answer: X‑ray survival curves showed increased survival if cells were left in stationary phase 6–12 hours after irradiation; tumor cells removed later after i
Card 6
Question: What is 'recovery from sublethal damage' as shown in split‑dose experiments?
Answer: When cells receive a first radiation dose and a second after a delay, survivors can repair damage so that their response resembles that of unirradiate
Card 7
Question: What does a split‑dose recovery experiment compare to show repair of sublethal damage?
Answer: It compares survival after two doses separated by a delay to survival after a single equivalent combined dose; increased survival with delay indicates
Card 8
Question: How did tumor oxygenation status affect repair of sublethal damage in the in vivo experiments described?
Answer: One‑day‑old tumors (predominantly oxygenated) and six‑day‑old tumors (hypoxic) showed differing recovery factors in split‑dose experiments, indicating
Card 9
Question: What happens to a multifraction survival curve when equal fractions are separated by enough time for complete repair of sublethal damage between fract
Answer: The shoulder of the single-dose survival curve is repeated for each fraction, yielding an effective survival curve that is exponential (a straight lin
Card 10
Question: How is D10 (dose for one decade of cell killing) related to D0?
Answer: D10 = 2.3 × D0.