ISOTOXIC DOSE ESCALATION IN THE TREATMENT OF LUNG CANCER BY MEANS OF HETEROGENEOUS DOSE DISTRIBUTIONS IN THE PRESENCE OF RESPIRATORY MOTION
ISOTOXIC DOSE ESCALATION IN THE TREATMENT OF LUNG CANCER BY MEANS OF HETEROGENEOUS DOSE DISTRIBUTIONS IN THE PRESENCE OF RESPIRATORY MOTION
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DOI：
10.1016/j.ijrobp.2010.12.001
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发表时间：
2011-11-01
影响因子：
7
通讯作者：
Brink, Carsten
中科院分区：
文献类型：
--
作者：
Baker, Mariwan;Nielsen, Morten;Brink, Carsten
目的：在存在分次呼吸运动的情况下，测试对均匀和适形剂量分布有效的边缘处方，并测试在考虑呼吸运动时，使用较小的边缘与不均匀剂量分布相结合是否允许等毒剂量递增。方法和材料：23例II-III期非小细胞肺癌患者接受了四维计算机断层扫描。在通气中期勾画大体肿瘤体积和临床靶体积（CTV）。通过使用标准边缘处方和患者特定呼吸模式计算CTV至计划靶体积（PTV）边缘。生成标准三维治疗计划，并在剩余呼吸阶段重新计算。重复计划，使CTV至PTV边缘在所有方向上相对于初始边缘减少2.5 mm和5 mm。计算时间平均剂量体积直方图（四维剂量体积直方图）以评估CTV至PTV边缘。最后，剂量逐步增加的计划，减少PTV，这样的平均肺剂量（辐射引起的肺炎的预测）等于平均肺剂量的计划，通过使用最初计算的margin.Results：减少标准利润率2.5毫米相比，食谱导致在太低的最低剂量为一些患者。一个组合的剂量递增和使用的异质性剂量分布能够增加约10%和20%的CTV到PTV边缘减少2.5 mm和5.0 mm，分别为目标的最小剂量。结论：边缘配方是有效的intrafractional呼吸诱导的肿瘤运动。在不均匀剂量分布的情况下，可以增加靶点剂量，而不会增加平均肺剂量。(C)2011 Elsevier Inc.
Purpose: To test, in the presence of intrafractional respiration movement, a margin recipe valid for a homogeneous and conformal dose distribution and to test whether the use of smaller margins combined with heterogeneous dose distributions allows an isotoxic dose escalation when respiratory motion is considered.Methods and Materials: Twenty-three Stage II-III non small-cell lung cancer patients underwent four-dimensional computed tomography scanning. The gross tumor volume and clinical target volume (CTV) were outlined in the mid-ventilation phase. The CTV-to-planning target volume (PTV) margin was calculated by use of a standard margin recipe and the patient-specific respiration pattern. Standard three-dimensional treatment plans were generated and recalculated on the remaining respiration phases. The planning was repeated for a CTV-to-PTV margin decreased by 2.5 and 5 mm relative to the initial margin in all directions. Time-averaged dose-volume histograms (four-dimensional dose-volume histograms) were calculated to evaluate the CTV-to-PTV margin. Finally, the dose was escalated in the plans with decreased PTV such that the mean lung dose (predictor of radiation-induced pneumonitis) was equal to mean lung dose in the plan by use of the initially calculated margin.Results: A reduction of the standard margin by 2.5 mm compared with the recipe resulted in too low of a minimum dose for some patients. A combination of dose escalation and use of heterogeneous dose distribution was able to increase the minimum dose to the target by approximately 10% and 20% for a CTV-to-PTV margin reduction of 2.5 mm and 5.0 mm, respectively.Conclusion: The margin recipe is valid for intrafractional respiration-induced tumor motions. It is possible to increase the dose to the target without increased mean lung dose with an inhomogeneous dose distribution. (C) 2011 Elsevier Inc.