AN ALGORITHM FOR MAXIMIZING THE PROBABILITY OF COMPLICATION-FREE TUMOR-CONTROL IN RADIATION-THERAPY
AN ALGORITHM FOR MAXIMIZING THE PROBABILITY OF COMPLICATION-FREE TUMOR-CONTROL IN RADIATION-THERAPY
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DOI：
10.1088/0031-9155/37/4/004
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发表时间：
1992-04-01
影响因子：
3.5
通讯作者：
BRAHME, A
中科院分区：
文献类型：
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作者：
KALLMAN, P;LIND, BK;BRAHME, A
新的放射生物学模型被用来描述肿瘤和正常组织的反应，并考虑到它们对照射量和所提供的剂量分布和细胞灵敏度的不均匀性的依赖。实现无并发症肿瘤控制的概率通过迭代算法最大化。该算法是通过将其应用到一维（1D）肿瘤模型，但也到一个更临床相关的2D情况下证明。新算法是n维的，因此它可以同时优化3D体积中的剂量输送，并且原则上还选择理想的射束方向、射束模态（光子、电子、中子等）和相应模态的最佳光谱分布。为了使计算时间合理，2D-3D问题是最实用的，并且通过选择照射核来预选合适的射束取向。因此，应选择能量沉积内核，以避免通过处于危险中的器官进行辐照。临床上建立的感兴趣组织的剂量反应参数用于使优化尽可能与手头的临床问题相关。该算法甚至可以用于选择不佳的内核，因为它总是尽可能地避免辐射有风险的器官。所产生的剂量分布将是最佳的空间分布和假设的放射生物学性质的肿瘤和正常组织的风险为内核选择。更具体地说，在正常组织中实现肿瘤控制而没有致命并发症的可能性被最大化。在临床实例中，在处于风险的敏感器官的边界处观察到降低的肿瘤剂量，但恰恰在肿瘤边界内产生增加的剂量。增加的肿瘤剂量具有这样的效果，即在危险器官的边界处剂量下降尽可能陡峭。
New radiobiological models are used to describe tumour and normal tissue reactions and to account for their dependence on the irradiated volume and inhomogeneities of the delivered dose distribution and cell sensitivity. The probability of accomplishing complication-free tumour control is maximized by an iterative algorithm. The algorithm is demonstrated by applying it to a one-dimensional (1D) tumour model but also to a more clinically relevant 2D case. The new algorithm is n-dimensional so it could simultaneously optimize the dose delivery in a 3D volume and in principle also select the ideal beam orientations, beam modalities (photons, electrons, neutrons, etc) and optimal spectral distributions of the corresponding modalities. To make calculation time reasonable, 2D-3D problems are most practical, and suitable beam orientations are preselected by the choice of irradiation kernel. The energy deposition kernel should therefore be selected in order to avoid irradiation through organs at risk. Clinically established dose response parameters for the tissues of interest are used to make the optimization as relevant as possible to the clinical problems at hand. The algorithm can be used even with a poorly selected kernel because it will always, as far as possible, avoid irradiating organs at risk. The generated dose distribution will be optimal with respect to the spatial distribution and assumed radiobiological properties of the tumour and normal tissues at risk for the kernel chosen. More specifically the probability of achieving tumour control without fatal complications in normal tissues is maximized. In the clinical examples a reduced tumour dose is seen at the border to sensitive organs at risk, but instead an increased dose just inside the tumour border is generated. The increased tumour dose has the effect that the dose fall-off is as steep as possible at the border to organs at risk.