运用数字体相关方法追踪呼吸过程中肺部肿瘤和胸腔的运动

目的 研究数字体相关（digital volume correlation，DVC）方法测量肺部肿瘤和胸腔随患者呼吸运动的变形及位移情况的可行性。方法 利用DVC跟踪胸腔内组织三维运动的算法，通过四维CT成像技术拍摄肺癌患者一个完整的呼吸过程。以吸气开始为初始状态，确定肿瘤和胸腔位置，运用DVC软件，分析初始状态下肺部4个特征体域在20%、40%、60%、80%和100%呼吸相位下以及胸腔上4个特征体域在100%呼吸相位下的三维位移值。结果 肿瘤的位移和变形的误差在1 mm以内，胸腔的位移和变形的误差在0.5 mm以内；肿瘤在呼吸过程中沿人体竖直方向运动最大,胸腔在吸气结束时刻沿人体前后方向运动最大。结论 DVC测试技术可用于检测呼吸过程中肺部肿瘤和胸腔等胸部组织的位移和变形情况。本研究为基于DVC方法实现肺部肿瘤无创、非射线、实时的图像引导放射治疗提供了依据。

Tracking Lung tumor and chest motion in the breathing process by digital volume correlation method

Objective To study the feasibility of using digital volume correlation (DVC) method to track displacement and deformation of lung tumor and chest during the period of respiration. Methods A DVC algorithm suitable for tracking 3D movement of tissues in chest was proposed. The 4D CT imaging technique was adopted to acquire images of a patient with lung cancer during one complete respiration stage. The inhalation was set as the initial stage for reference, to determine the locations of lung cancer and chest. Four specified regions of both the tumor and chest at the initiation of inhalation stage were selected. The corresponding 3D displacement of lung in the following 5 inhalation phase stages, i.e. 20%, 40% 60%, 80% and 100% as well as 3D displacement of chest in 100% inhalation phase stage were analyzed by DVC software. Results The displacement and deformation error of tumor was within 1 mm, while that of chest was within 0.5 mm. The maximum displacement of tumor presented itself along the vertical direction of human body during respiration, while that of chest at the end of inhalation stage appeared along the front and back direction of human body. Conclusions DVC methods can be potentially used to detect displacement and deformation of body tissues such as lung tumor and chest during the respiratory cycle. This study provides references for noninvasive, non X-ray, real-time image-guided radiation therapy for lung cancer based on DVC method.