Radiation response of hypoxic and generally heterogeneous tissues
Radiation response of hypoxic and generally heterogeneous tissues
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DOI：
10.1080/09553000110113038
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发表时间：
2002-05-01
影响因子：
2.6
通讯作者：
Brahme, A
中科院分区：
文献类型：
--
作者：
Nilsson, J;Lind, BK;Brahme, A
目的：基于生物学的治疗优化可以基于克隆形成细胞数量和宏观组织体素上的细胞辐射反应的局部平均值。肿瘤中的氧气梯度很大，往往会在细胞水平上导致辐射抵抗的微观分布，远远超出当前诊断和放射治疗方法的几何分辨率。目前的工作集中于通过组织氧合模型来量化这种微观分布的放射生物学效应，并在微观和宏观尺度上计算相应的辐射响应。材料和方法：以微血管密度和异质性为主要参数，建立了一个简单的组织血管模型。给出了计算抗辐射能力和克隆密度一般不均匀的组织的有效辐射响应的新的解析表达式。结果：在不同参数设置下得到的氧分布与临床测量的肿瘤和正常组织的氧分布非常吻合。除了血管密度外，血管的异质性也是评估组织缺氧程度的一个重要因素。结果表明，由有效初始克隆数N-0，N-Ef和有效辐射阻力D-0，D-Ef可以准确地计算出具有异质辐射抗性的组织的局部和整体剂量-效应关系。例如，根据测量的氧气分布推导出新的公式来计算这些量。结论：通过这里提出的新方法，现有的使用标准的肿瘤类型或患者特定的氧合数据来测量微观和宏观氧气分布的技术可以用于基于生物的治疗计划的优化。
Purpose: Biologically based treatment optimisation can be based on the local mean values of the number of clonogenic cells and the cellular radiation response taken over macroscopic tissue voxels. Steep oxygen gradients in tumours may often lead to microscopic distributions of radiation resistance at the cellular level, far beyond the geometrical resolution of current diagnostic and radiotherapeutic methods. The present work focuses on quantifying the radiobiological effect of such microscopic distributions through tissue-oxygenation modelling and on calculating the corresponding radiation response on both micro- and macroscopic scales.Materials and methods: A simple model of tissue vasculature was developed with microvascular density and heterogeneity as its main parameters. New analytical expressions are presented for calculating the effective radiation response of tissues with generally heterogeneous radiation resistance and clonogen density.Results : The oxygen distributions derived for different parameter sets agree very well with clinically measured oxygen distributions for both tumours and normal tissues. In addition to the vascular density, vascular heterogeneity is an important factor while estimating the hypoxic fraction in tissue. It is shown that both the local and global dose-response relation for tissues with heterogeneous radiation resistance can be accurately calculated from the effective initial clonogen number N-0,N-eff and the effective radiation resistance D-0,D-eff. New equations are derived for calculating these quantities, for instance, from measured oxygen distributions.Conclusions : With the new methods presented here, existing techniques to measure the micro- and macroscopic oxygen distribution either using standard tumour-type or patient-specific oxygenation data can be used for biologically based treatment plan optimisation.