Ramos-Méndez J, Perl J, Schümann J, Shin J, Paganetti H, Faddegon B
Deparment of Radiation Oncology, University of California at San Francisco, San Francisco, CA 94143, USA.
Phys Med Biol. 2015 Jul 7;60(13):5037-52. doi: 10.1088/0031-9155/60/13/5037. Epub 2015 Jun 10.
The aim of this work was to develop a framework for modeling organ effects within TOPAS (TOol for PArticle Simulation), a wrapper of the Geant4 Monte Carlo toolkit that facilitates particle therapy simulation. The DICOM interface for TOPAS was extended to permit contour input, used to assign voxels to organs. The following dose response models were implemented: The Lyman-Kutcher-Burman model, the critical element model, the population based critical volume model, the parallel-serial model, a sigmoid-based model of Niemierko for normal tissue complication probability and tumor control probability (TCP), and a Poisson-based model for TCP. The framework allows easy manipulation of the parameters of these models and the implementation of other models. As part of the verification, results for the parallel-serial and Poisson model for x-ray irradiation of a water phantom were compared to data from the AAPM Task Group 166. When using the task group dose-volume histograms (DVHs), results were found to be sensitive to the number of points in the DVH, with differences up to 2.4%, some of which are attributable to differences between the implemented models. New results are given with the point spacing specified. When using Monte Carlo calculations with TOPAS, despite the relatively good match to the published DVH's, differences up to 9% were found for the parallel-serial model (for a maximum DVH difference of 2%) and up to 0.5% for the Poisson model (for a maximum DVH difference of 0.5%). However, differences of 74.5% (in Rectangle1), 34.8% (in PTV) and 52.1% (in Triangle) for the critical element, critical volume and the sigmoid-based models were found respectively. We propose a new benchmark for verification of organ effect models in proton therapy. The benchmark consists of customized structures in the spread out Bragg peak plateau, normal tissue, tumor, penumbra and in the distal region. The DVH's, DVH point spacing, and results of the organ effect models are provided. The models were used to calculate dose response for a Head and Neck patient to demonstrate functionality of the new framework and indicate the degree of variability between the models in proton therapy.
本工作的目的是在TOPAS（粒子模拟工具）中开发一个用于对器官效应进行建模的框架，TOPAS是Geant4蒙特卡罗工具包的一个包装器，便于进行粒子治疗模拟。TOPAS的DICOM接口得到扩展，以允许输入轮廓，用于将体素分配给器官。实现了以下剂量反应模型：莱曼-库彻-伯曼模型、关键元素模型、基于群体的关键体积模型、平行-串联模型、基于S形曲线的Niemierko正常组织并发症概率和肿瘤控制概率（TCP）模型，以及基于泊松分布的TCP模型。该框架允许轻松操纵这些模型的参数并实现其他模型。作为验证的一部分，将水模体X射线照射的平行-串联模型和泊松模型的结果与美国医学物理师协会任务组166的数据进行了比较。当使用任务组剂量体积直方图（DVH）时，发现结果对DVH中的点数敏感，差异高达2.4%，其中一些差异可归因于所实现模型之间的差异。给出了指定点间距的新结果。当使用TOPAS进行蒙特卡罗计算时，尽管与已发表的DVH相对匹配，但平行-串联模型的差异高达9%（最大DVH差异为2%），泊松模型的差异高达0.5%（最大DVH差异为0.5%）。然而，关键元素模型、关键体积模型和基于S形曲线的模型在Rectangle1中的差异分别为74.5%、在PTV中的差异为34.8%以及在Triangle中的差异为52.1%。我们提出了一个用于质子治疗中器官效应模型验证的新基准。该基准包括扩展布拉格峰平台、正常组织、肿瘤、半影和远端区域中的定制结构。提供了DVH、DVH点间距以及器官效应模型的结果。使用这些模型计算了一名头颈患者的剂量反应，以展示新框架的功能，并指出质子治疗中模型之间的变异程度。
