The Time Factor for Late Reactions in Radiotherapy: Repopulation or Intracellular Repair?
When doses in radiotherapy are protracted over increasing periods of time, it is generally considered that very little extra dose is required (the time factor) to reach tolerance for late reactions. This is in contrast to repopulation in early-reacting tissues and in tumors (e.g., Withers et al. 1988). Nevertheless, time factors have been reported for late-reacting tissues, and even small values could sometimes be more important than in the cases of early-reacting normal tissues and tumors because of the greater steepness of dose-incidence curves for injury in late-reacting organs (e.g., Thames et al. 1989; Hendry 1989).
KeywordsLinear Energy Transfer Late Reaction Relative Biological Effectiveness Premature Chromosome Condensation Dose Reduction Factor
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