Miura Hideharu, Ozawa Shuichi, Kawabata Hideo, Doi Yoshiko, Kenjou Masahiro, Furukawa Kengo, Nakao Minoru, Nagata Yasushi
Hiroshima High-Precision Radiotherapy Cancer Center, Hiroshima, Japan.
Hiroshima High-Precision Radiotherapy Cancer Center, Hiroshima, Japan; Department of Radiation Oncology, Institute of Biomedical & Health Science, Hiroshima University, Hiroshima, Japan.
Phys Med. 2016 Dec;32(12):1570-1574. doi: 10.1016/j.ejmp.2016.11.110. Epub 2016 Nov 23.
Published organ motion data have been collected from measurements of a limited number of points within the organ, the centroid, or the edge of the organ. These are derived from the spatial characteristics of respiratory induced motion; however, this approach does not consider non-rigid organ deformation. We propose a novel quantitative method for evaluating respiratory induced organ motion using Deformable Image Registration (DIR).
Two phases from a 4-dimensional computed tomography (4D CT) dataset at maximum inspiration and expiration were each taken from five patients. The left and right lungs, esophagus, stomach, spinal cord, and liver were manually contoured in the end-expiration phase. The hybrid deformable registration algorithm of the RayStation treatment planning system (TPS) was used to deform the end-expiration phase to the end-inspiration phase. From this, the deformation vector field (DVF) was calculated. DVFs consist of DVF (left-right), DVF (anterior-posterior), and DVF (superior-inferior) as separate files. We calculated the vector volume histogram (VVH) and L (maximum absolute vector of the organ) to evaluate every vector for each individual organ. We also measured respiratory organ motion from the position of the organ centroid in two phases.
VVH enabled us to find the absolute distance and volume of the organ contributing to motion points on the curve. Organ motion using the centroid method was smaller than L using VVH. Using the centroid method, it is difficult to evaluate the deformable organ motion.
VVH may be a useful technique in evaluating organ volumetric change during respiratory organ motion.
已发表的器官运动数据是通过对器官内有限数量的点、质心或器官边缘进行测量而收集的。这些数据源自呼吸诱导运动的空间特征；然而，这种方法未考虑非刚性器官变形。我们提出一种使用可变形图像配准（DIR）来评估呼吸诱导器官运动的新型定量方法。
从五名患者的四维计算机断层扫描（4D CT）数据集中获取最大吸气和呼气时的两个阶段图像。在呼气末阶段手动勾勒出左肺、右肺、食管、胃、脊髓和肝脏的轮廓。使用RayStation治疗计划系统（TPS）的混合可变形配准算法将呼气末阶段图像变形为吸气末阶段图像。由此计算出变形矢量场（DVF）。DVF由DVF（左右）、DVF（前后）和DVF（上下）作为单独文件组成。我们计算了矢量体积直方图（VVH）和L（器官的最大绝对矢量）以评估每个单独器官的每个矢量。我们还从两个阶段器官质心的位置测量了呼吸器官运动。
VVH使我们能够找到对曲线上运动点有贡献的器官的绝对距离和体积。使用质心方法的器官运动小于使用VVH的L。使用质心方法难以评估可变形器官运动。
VVH可能是评估呼吸器官运动期间器官体积变化的一种有用技术。
