Image-driven, model-based 3D abdominal motion estimation for MR-guided radiotherapy
Image-driven, model-based 3D abdominal motion estimation for MR-guided radiotherapy
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DOI：
10.1088/0031-9155/61/14/5335
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发表时间：
2016-07-21
影响因子：
3.5
通讯作者：
van den Berg, Cornelis A. T.
中科院分区：
文献类型：
--
作者：
Stemkens, Bjorn;Tijssen, Rob H. N.;van den Berg, Cornelis A. T.
呼吸运动在传统上使用大边界的腹部放射治疗中引入了大量的不确定性。MR-Linac将为在辐射前和治疗期间获取高分辨率MR图像提供机会。然而，体积MRI时间序列不能以足够的时间分辨率来表征3D肿瘤和危险器官的运动。在这项研究中，我们提出了一种基于快速2D成像和基于呼吸相关MRI的受试者特定运动模型的方法来估计具有高空间和时间分辨率的3D变形矢量场（DVF）。在预射束阶段，采集回顾性排序的4D-MRI，使用主成分分析从该运动参数化该运动。该运动模型与快速2D电影-MR图像结合使用，该图像在辐射期间采集，以生成具有476 ms的时间分辨率的全视场3D DVF。使用MR兼容运动体模确定输入数据（4D-MRI和2D多切片采集）和拟合程序的几何精度，发现平均为1.0-1.5 mm。该框架在7名健康志愿者的胰腺和肾脏上进行了测试。使用其中一个2D切片独立验证计算的运动，平均误差为1.45 mm。计算的3D DVF可用于回顾性治疗模拟，计划评估，或在MR引导放射治疗中基于受试者特定的基础上确定肿瘤和危险器官的累积剂量。
Respiratory motion introduces substantial uncertainties in abdominal radiotherapy for which traditionally large margins are used. The MR-Linac will open up the opportunity to acquire high resolution MR images just prior to radiation and during treatment. However, volumetric MRI time series are not able to characterize 3D tumor and organ-at-risk motion with sufficient temporal resolution.In this study we propose a method to estimate 3D deformation vector fields (DVFs) with high spatial and temporal resolution based on fast 2D imaging and a subject-specific motion model based on respiratory correlated MRI.In a pre-beam phase, a retrospectively sorted 4D-MRI is acquired, from which the motion is parameterized using a principal component analysis. This motion model is used in combination with fast 2D cine-MR images, which are acquired during radiation, to generate full field-of-view 3D DVFs with a temporal resolution of 476 ms.The geometrical accuracies of the input data (4D-MRI and 2D multi-slice acquisitions) and the fitting procedure were determined using an MR-compatible motion phantom and found to be 1.0-1.5 mm on average. The framework was tested on seven healthy volunteers for both the pancreas and the kidney. The calculated motion was independently validated using one of the 2D slices, with an average error of 1.45 mm.The calculated 3D DVFs can be used retrospectively for treatment simulations, plan evaluations, or to determine the accumulated dose for both the tumor and organs-at-risk on a subject-specific basis in MR-guided radiotherapy.