Optimum overall times II: Extended modelling for head and neck radiotherapy
Optimum overall times II: Extended modelling for head and neck radiotherapy
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DOI：
10.1016/j.clon.2007.11.003
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发表时间：
2008-03-01
影响因子：
3.4
通讯作者：
Fowler, J. F.
中科院分区：
文献类型：
--
作者：
Fowler, J. F.
目的：该杂志上的一篇论文（第1部分）得出结论，没有明显的最佳总时间，至少有70个1的分数。15戈伊，每日2次，共50天。最大耐受肿瘤剂量从21或23天的最佳短时间表增加到50天仅2%。在第一部分中只模拟了这个范围，因为它涵盖了最少和最多的分数，以及可能在实践中使用的最长的总时间。大多数英国时间表，通常每周使用五次，产生的肿瘤有效剂量比其他发达国家的最佳时间表低约10%。本文涵盖了更广泛的分数范围从1到115，从1到80天。本附录还更正了第一部分各表中的一些数字错误。材料和方法：使用标准线性二次模型，假设在第一个α/β = 10戈伊，α = 0.35 ln/戈伊，Tk = 21天，Tp = 3天的肿瘤，但与Tk = 7天，Tp = 2.5戈伊的急性粘膜反应，如前所述。晚期并发症限制为70戈伊，急性限制为51戈伊（均为2戈伊分割）。结果：最佳值为22-32天（每周5次，每次1次）和42-49天（每周10次，每次2次）。再增殖造成肿瘤剂量快速下降后30天，一个分数/天，但直到50天后，两个分数/天，所以没有看到在第一部分，其过于实际的结束时间。结论：生物建模可以外推计算的边界外公布的治疗计划，以澄清边界的情况。如果每天使用两次，放射治疗的最佳时间表可以可靠地提供更多的肿瘤控制。潜在增益相当于该模型给出的2戈伊的两个分数。然而，如果优化设计，晚期并发症将减少一些几乎等同于肿瘤的较短时间表。
Aims: A previous paper in this journal (part 1) concluded that there was no pronounced optimum overall time, at least up to 70 fractions of 1. 15 Gy at two fractions/day in 50 days. The maximum tolerable tumour doses increased only 2% from the best short schedules of 21 or 23 days to those of 50 days. Only this range was modelled in part I because it covered the fewest and the most fractions, and the longest overall times that will probably be used in practice. Most UK schedules, typically using five fractions a week, yield tumour effective doses about 10% less than the best schedules in other developed countries. The present paper covers a much wider range of fraction numbers from one to 115, and from 1 to 80 days. Some numerical errors in the Tables in part I are also corrected in the present appendix. These made no difference to the main conclusions just described.Materials and methods: Standard linear quadratic modelling was used, assuming at first alpha/beta = 10 Gy, alpha = 0.35 ln/Gy, Tk = 21 days, Tp = 3 days for tumours, but with Tk = 7 days, Tp = 2.5 Gy for acute mucosal reactions, as before. A late complications constraint of 70 Gy was accepted, and an acute constraint of 51 Gy (both at 2 Gy fractions). Alternative values of more rapid or slower repopulation were also explored (Tp = 2 days or Tp = 5 days, respectively).Results: Optimal values were shown at 22-32 days for one fraction/day five times a week, and at 42-49 days for two fractions/day at 10 fractions/week. Repopulation caused a rapid fall in tumour dose after 30 days with one fraction/day, but not until after 50 days with two fractions/day, and so was not seen in part I with its too-practical end time.Conclusions: Biological modelling can extrapolate calculations outside the borders of published treatment schedules to clarify borderline situations. Optimum schedules in radiotherapy can reliably give more tumour control if two fractions/day are used. The potential gains are equivalent to about two fractions of 2 Gy as given by this modelling. However, the late complications will be less with some nearly tumour equivalent shorter schedules if optimally designed.