A patient-specific respiratory model of anatomical motion for radiation treatment planning
A patient-specific respiratory model of anatomical motion for radiation treatment planning
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DOI：
10.1118/1.2804576
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发表时间：
2007-12-01
期刊：
影响因子：
3.8
通讯作者：
Mageras, Gig S.
中科院分区：
文献类型：
--
作者：
Zhang, Qinghui;Pevsner, Alex;Mageras, Gig S.
呼吸运动的建模对于更准确地理解和计算其对放射治疗胸腹癌剂量的影响是重要的。我们开发了一个呼吸诱导的胸腔器官运动模型，没有通常采用的重复呼吸循环假设。该模型基于参考三维（3D）图像（呼气结束时）和膈膜在不同时间点的位置描述患者体内感兴趣的体积的运动。输入数据是接受非小细胞肺癌治疗的患者的呼吸相关CT （RCCT）图像，包括呼吸周期十个阶段的三维图像，包括隔膜位置。可变形图像配准算法计算将每个3D图像映射到参考3D图像的变形场。采用主成分分析方法，以参数化膜片运动的三维变形场。我们表明，前两个主成分足以准确和完整地描述器官运动在四个病人的数据。通常出现在呼吸中期状态的RCCT图像中的伪影在模型生成的图像中被减少了。将参数化的三维变形场成功应用于几天后获得的同一患者的RCCT数据，进一步验证了模型的有效性。我们已经开发了一种预测患者呼吸诱导器官运动的方法，该方法有可能提高放射治疗剂量计算的准确性。该模型可能存在的局限性是，当肺肿瘤与膈位置的相关性不太可靠时，如肿瘤位置优越，肿瘤-膈相关性发生交叉变化。有限数量的临床病例表明，但不能证实，该模型适用于广泛的患者。(C) 2007年美国医学物理学家协会。
The modeling of respiratory motion is important for a more accurate understanding and accounting of its effect on dose to cancers in the thorax and abdomen by radiotherapy. We have developed a model of respiration-induced organ motion in the thorax without the commonly adopted assumption of repeatable breath cycles. The model describes the motion of a volume of interest within the patient based on a reference three-dimensional (3D) image (at end expiration) and the diaphragm positions at different time points. The input data are respiration-correlated CT (RCCT) images of patients treated for non-small- cell lung cancer, consisting of 3D images, including the diaphragm positions, at ten phases of the respiratory cycle. A deformable image registration algorithm calculates the deformation field that maps each 3D image to the reference 3D image. A principal component analysis is performed to parameterize the 3D deformation field in terms of the diaphragm motion. We show that the first two principal components are adequate to accurately and completely describe the organ motion in the data of four patients. Artifacts in the RCCT images that commonly occur at the mid-respiration states are reduced in the model-generated images. Further validation of the model is demonstrated in the successful application of the parameterized 3D deformation field to RCCT data of the same patient but acquired several days later. We have developed a method for predicting respiration-induced organ motion in patients that has potential for improving the accuracy of dose calculation in radiotherapy. Possible limitations of the model are cases where the correlation between lung tumor and diaphragm position is less reliable such as superiorly situated tumors and interfraction changes in tumor-diaphragm correlation. The limited number of clinical cases examined suggests, but does not confirm, the model's applicability to a wide range of patients. (C) 2007 American Association of Physicists in Medicine.