The linear-quadratic model and most other common radiobiological models result in similar predictions of time-dose relationships
The linear-quadratic model and most other common radiobiological models result in similar predictions of time-dose relationships
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DOI：
10.2307/3579648
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发表时间：
1998-07-01
影响因子：
3.4
通讯作者：
Sachs, RK
中科院分区：
文献类型：
--
作者：
Brenner, DJ;Hlatky, LR;Sachs, RK
辐射生物学中的基本工具之一是描述时间-剂量关系的形式主义。例如，当时间照射模式改变时，需要可靠地预测辐射等效剂量。目前最常用的工具是线性二次（LQ）形式主义，它通过一个特殊的函数形式，广义Lea-Catcheside时间因子G，描述了分馏和剂量延长效应。我们调查的LQ形式主义的关系，以描述其他常见的讨论放射生物学模型在其预测的时间-剂量关系。我们表明，广泛的放射生物学模型所描述的形式主义，其中微扰计算产生的标准LQ关系的剂量分割/延长，包括相同的广义时间因子，G。这种近似的等价性不仅适用于描述二进制误修复模型的形式主义，这在概念上类似于LQ，而且适用于描述模型的形式主义，该模型体现了对时间-剂量效应的非常不同的解释，即修复能力的饱和。在放射治疗的应用方面，我们表明，一个典型的饱和修复形式主义预测几乎相同的依赖性，为延长效应的LQ形式主义，在临床相关剂量每部分。对于低剂量率暴露，预测之间的等效性对于早期反应终点（如肿瘤控制）也是相同的，但对于晚期反应终点则不太一样。总体而言，使用LQ形式主义来预测剂量-时间关系是一种非常稳健的方法，其依赖于详细的生物物理机制知识的程度低于先前的想法，因为各种概念上不同的生物物理模型在合理的近似下导致LQ关系，包括辐射研究学会的广义时间因子G（C）1998的标准形式。
One of the fundamental tools in radiation biology is a formalism describing time-dose relationships. For example, there is a need for reliable predictions of radiotherapeutic isoeffect doses when the temporal exposure pattern is changed. The most commonly used tool is now the linear-quadratic (LQ) formalism, which describes fractionation and dose-protraction effects through a particular functional form, the generalized Lea-Catcheside time factor, G. We investigate the relationship of the LQ formalism to those describing other commonly discussed radiobiological models in terms of their predicted time-dose relationships. We show that a broad range of radiobiological models are described by formalisms in which a perturbation calculation produces the standard LQ relationship for dose fractionation/protraction, including the same generalized time factor, G. This approximate equivalence holds not only for the formalisms describing binary misrepair models, which are conceptually similar to LQ, but also for formalisms describing models embodying a very different explanation for time-dose effects, namely saturation of repair capacity. In terms of applications to radiotherapy, we show that a typical saturable repair formalism predicts practically the same dependences for protraction effects as does the LQ formalism, at clinically relevant doses per fraction. For low-dose-rate exposure, the same equivalence between predictions holds for early-responding end points such as tumor control, but less so for late-responding end points. Overall, use of the LQ formalism to predict dose-time relationships is a notably robust procedure, depending less than previously thought on knowledge of detailed biophysical mechanisms, since various conceptually different biophysical models lead, in a reasonable approximation, to the LQ relationship including the standard form of the generalized time factor, G, (C) 1998 by Radiation Research Society.