Department of Radiation Oncology, University of Michigan, Ann Arbor, Michigan 48109, USA.
Med Phys. 2007 Jul;34(7):2785-8. doi: 10.1118/1.2739812.
The purpose of this study was to investigate the feasibility of a simple deformable phantom as a QA tool for testing and validation of deformable image registration algorithms. A diagnostic thoracic imaging phantom with a deformable foam insert was used in this study. Small plastic markers were distributed through the foam to create a lattice with a measurable deformation as the ground truth data for all comparisons. The foam was compressed in the superior-inferior direction using a one-dimensional drive stage pushing a flat "diaphragm" to create deformations similar to those from inhale and exhale states. Images were acquired at different compressions of the foam and the location of every marker was manually identified on each image volume to establish a known deformation field with a known accuracy. The markers were removed digitally from corresponding images prior to registration. Different image registration algorithms were tested using this method. Repeat measurement of marker positions showed an accuracy of better than 1 mm in identification of the reference marks. Testing the method on several image registration algorithms showed that the system is capable of evaluating errors quantitatively. This phantom is able to quantitatively assess the accuracy of deformable image registration, using a measure of accuracy that is independent of the signals that drive the deformation parameters.
本研究旨在探讨一种简单的变形体模作为测试和验证变形图像配准算法的 QA 工具的可行性。本研究使用了带有可变形泡沫插入物的诊断性胸部成像体模。小塑料标记物分布在泡沫中，形成一个具有可测量变形的晶格，作为所有比较的真实数据。通过使用一维驱动台在上下方向上压缩泡沫，推动一个平坦的“隔膜”来创建类似于吸气和呼气状态的变形。在泡沫的不同压缩下获取图像，并在每个图像体积上手动识别每个标记的位置，以建立具有已知精度的已知变形场。在注册之前，从相应的图像中数字删除标记。使用该方法测试了不同的图像配准算法。标记位置的重复测量显示，参考标记的识别精度优于 1 毫米。在几种图像配准算法上进行测试表明，该系统能够定量评估误差。该体模能够使用与驱动变形参数的信号无关的准确性度量来定量评估变形图像配准的准确性。
