Is it sensible to "deform" dose? 3D experimental validation of dose-warping
Is it sensible to "deform" dose? 3D experimental validation of dose-warping
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DOI：
10.1118/1.4736534
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发表时间：
2012-08-01
期刊：
影响因子：
3.8
通讯作者：
Franich, R. D.
中科院分区：
文献类型：
--
作者：
Yeo, U. J.;Taylor, M. L.;Franich, R. D.
目的：放射治疗中解剖变形的剂量累积策略是一个重要的研究课题。存在用于基于患者图像集的剂量变形的算法，尽管这些算法有时是有争议的，因为并非所有这样的图像计算都受到物理定律的约束。虽然肿瘤和器官运动已经是一个关键的研究领域相当长的时间，变形是越来越感兴趣。在这项工作中，我们展示了一个完整的3D实验验证的结果，从一系列的剂量变形算法可在public domain.Methods：我们最近开发了第一个组织等效的，完整的3D变形剂量体模“DEFGEL。“为了评估基于变形图像配准（DEFGEL）的剂量扭曲的准确性，我们测量了DEFGEL剂量计未变形和变形状态下的剂量，并将其与计划剂量和扭曲剂量进行了比较。通过这种方式，我们直接评估了11种不同算法的剂量扭曲计算的准确性。我们已经这样做了一系列的立体定向照射计划和类型和大小的deformation.Results：原来的霍恩和Schunck算法被证明是最好的执行的11个算法trialled。比较该方法的测量和剂量扭曲计算，发现对于10 × 10 mm（2）的方形射野，γ（3%/3 mm）= 99.9%;对于20 × 20 mm（2）的十字形射野，γ（3%/3 mm）= 99.1%;对于根据患者治疗计划调整的多个动态弧（0.413 cm 3 PTV）治疗，y（3%3mm）= 95%。在每种情况下，一致性与不存在变形的情况下测量和计算（计划）剂量分布之间的比较相当，但始终低于比较。通过体积中任何体素经历的最大位移测量的变形的幅度对翘曲剂量分布的准确性具有最大影响。考虑到方场的情况，（类似于9 mm）产生伽马（3%/3 mm）= 99.9%的一致性，而最显著的变形（类似于20 mm）产生Y-3%/3 mm = 96.7%的一致性。结论：我们已经证实，对于一系列代表解剖目标中可观察到的质量和密度守恒变形，基于DIR的剂量扭曲可以产生剂量分布的准确预测。在不同算法的结果之间可以看到实质性的差异，这表明在应用于剂量扭曲之前，应该仔细检查抗辐射性能。我们已经证明，DEFGEL变形剂量计可以用来评估直接测量的剂量翘曲结果的准确性和性能。(C)2012年美国医学物理学家协会。[http：//dx.doi.org/10.1118/1.4736534]
Purpose: Strategies for dose accumulation in deforming anatomy are of interest in radiotherapy. Algorithms exist for the deformation of dose based on patient image sets, though these are sometimes contentious because not all such image calculations are constrained by physical laws. While tumor and organ motion has been a key area of study for a considerable amount of time, deformation is of increasing interest. In this work, we demonstrate a full 3D experimental validation of results from a range of dose deformation algorithms available in the public domain.Methods: We recently developed the first tissue-equivalent, full 3D deformable dosimetric phantom "DEFGEL." To assess the accuracy of dose-warping based on deformable image registration (DIR), we have measured doses in undeformed and deformed states of the DEFGEL dosimeter and compared these to planned doses and warped doses. In this way we have directly evaluated the accuracy of dose-warping calculations for 11 different algorithms. We have done this for a range of stereotactic irradiation schemes and types and magnitudes of deformation.Results: The original Horn and Schunck algorithm is shown to be the best performing of the 11 algorithms trialled. Comparing measured and dose-warped calculations for this method, it is found that for a 10 x 10 mm(2) square field, gamma(3%/3mm) = 99.9%; for a 20 x 20 mm(2) cross-shaped field, gamma(3%/3mm) = 99.1%; and for a multiple dynamic arc (0.413 cm3 PTV) treatment adapted from a patient treatment plan, y(3%3mm) = 95%. In each case, the agreement is comparable to but consistently less than comparison between measured and calculated (planned) dose distributions in the absence of deformation. The magnitude of the deformation, as measured by the largest displacement experienced by any voxel in the volume, has the greatest influence on the accuracy of the warped dose distribution. Considering the square field case, the smallest deformation (similar to 9 mm) yields agreement of gamma(3%/3mm) = 99.9%, while the most significant deformation (similar to 20 mm) yields agreement of Y-3%/3mm = 96.7%.Conclusions: We have confirmed that, for a range of mass and density conserving deformations representative of those observable in anatomical targets, DIR-based dose-warping can yield accurate predictions of the dose distribution. Substantial differences can be seen between the results of different algorithms indicating that DIR performance should be scrutinized before application to dose-warping. We have demonstrated that the DEFGEL deformable dosimeter can be used to evaluate DIR performance and the accuracy of dose-warping results by direct measurement. (C) 2012 American Association of Physicists in Medicine. [http://dx.doi.org/10.1118/1.4736534]