MEDRADSC 3U03 Lecture Notes - Lecture 5: Doubling Time, European Organisation For Research And Treatment Of Cancer, Cytotoxicity
4 Jan 2017
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Lecture 5 factors influencing tissue and organ radiosensitivity part 1 (1) The multifraction regimens commonly used in conventional radiation therapy are largely based on experiments performed in the 1920s and 1930s. Rams could not be sterilized with a single large dose of radiation without severe damage to the skin of the scrotum. Spreading out the dose over weeks resulted in sterilization without the unacceptable skin damage. Fractionation of the radiation dose generally produces better tumour control for a given level of normal-tissue toxicity than a single large dose. To deliver as much radiation as we can. The efficacy of fractionation can be based on 4 factors. Spares normal tissue because time between doses allows for repair. Increases damage to the tumour because it allows tumour to be reoxygenated. Redistribution of tumour cells into radiosensitive phases of the cell cycle increase cell killing.
