Guerrero Thomas, Zhang Geoffrey, Huang Tzung-Chi, Lin Kang-Ping
Division of Radiation Oncology, The University of Texas M D Anderson Cancer Center, Houston, TX 77030, USA.
Phys Med Biol. 2004 Sep 7;49(17):4147-61. doi: 10.1088/0031-9155/49/17/022.
The purpose of this work was to develop and validate an automated method for intrathoracic tumour motion estimation from breath-hold computed tomography (BH CT) imaging using the three-dimensional optical flow method (3D OFM). A modified 3D OFM algorithm provided 3D displacement vectors for each voxel which were used to map tumour voxels on expiration BH CT onto inspiration BH CT images. A thoracic phantom and simulated expiration/inspiration BH CT pairs were used for validation. The 3D OFM was applied to the measured inspiration and expiration BH CT images from one lung cancer and one oesophageal cancer patient. The resulting displacements were plotted in histogram format and analysed to provide insight regarding the tumour motion. The phantom tumour displacement was measured as 1.20 and 2.40 cm with full-width at tenth maximum (FWTM) for the distribution of displacement estimates of 0.008 and 0.006 cm, respectively. The maximum error of any single voxel's motion estimate was 1.1 mm along the z-dimension or approximately one-third of the z-dimension voxel size. The simulated BH CT pairs revealed an rms error of less than 0.25 mm. The displacement of the oesophageal tumours was nonuniform and up to 1.4 cm, this was a new finding. A lung tumour maximum displacement of 2.4 cm was found in the case evaluated. In conclusion, 3D OFM provided an accurate estimation of intrathoracic tumour motion, with estimated errors less than the voxel dimension in a simulated motion phantom study. Surprisingly, oesophageal tumour motion was large and nonuniform, with greatest motion occurring at the gastro-oesophageal junction.
这项工作的目的是开发并验证一种使用三维光流法（3D OFM）从屏气计算机断层扫描（BH CT）成像估计胸内肿瘤运动的自动化方法。一种改进的3D OFM算法为每个体素提供三维位移矢量，这些矢量用于将呼气期BH CT上的肿瘤体素映射到吸气期BH CT图像上。使用胸部体模和模拟的呼气/吸气期BH CT图像对进行验证。将3D OFM应用于一名肺癌患者和一名食管癌患者测量得到的吸气期和呼气期BH CT图像。将得到的位移以直方图形式绘制并进行分析，以深入了解肿瘤运动情况。体模肿瘤位移在位移估计分布的十分之一最大宽度（FWTM）处分别测量为1.20 cm和2.40 cm，位移估计的FWTM分别为0.008 cm和0.006 cm。任何单个体素运动估计的最大误差在z维度上为1.1 mm，约为z维度体素大小的三分之一。模拟的BH CT图像对显示均方根误差小于0.25 mm。食管癌的位移不均匀，最大可达1.4 cm，这是一个新发现。在所评估的病例中发现肺肿瘤最大位移为2.4 cm。总之，在模拟运动体模研究中，3D OFM提供了胸内肿瘤运动的准确估计，估计误差小于体素尺寸。令人惊讶的是，食管肿瘤运动较大且不均匀，最大运动发生在胃食管交界处。
