Surgical simulation with computer assisted neurosurgical system

该项目的目的是从CT或MR图像中生成患者大脑的三维实体模型，并使其能够作为术前预演进行模拟手术。这将大大提高神经外科手术的准确性和安全性。我们首先开发了半自动图像分割，使区分区域的解剖结构，从CT或MR图像。传统上，解剖结构是简单地区分根据黑色和白色水平或像素值，组织的不均匀性或噪声漂移的图像，然而，妨碍严格的组织分割。针对这一问题，本文分析了感兴趣区域的图像特征，确定了最佳分割参数。然后，我们顺序地将几个图像滤波器应用于CT或MR图像以获得组织轮廓曲线，操作者立即检查这些曲线并将其存储在图像处理计算机中。使用组织轮廓数据，患者头部的三维线框图像很容易显示在屏幕上。其次，我们制作了实体模型。将轮廓线印在与CT或MR切片厚度相同的蜡粘土板上。沿轮廓线沿着切割板并编译以重建实体模型。最后，我们将实体模型固定在手术台上，并在神经外科导航仪“CANS Navigator”下用小刮刀进行手术模拟。使用导航仪记录程序，并在实际操作时回放。

The aim of the project is to produce 3 dimensional solid model of the patient brain from CT or MR images and to make it possible to perform simulation surgery on it as the preoperative rehearsal. This will enhance neurosurgical accuracy and safeness greatly.We first developed the semi-automated image segmentation that enable to discriminate the area of anatomical structures from CT or MR images. Conventionally, anatomical structures were simply discriminated according to the black and white levels or pixel values, tissue inhomogeniety or noise drifts of the images, however, hamper the strict tissue segmentation. To solve this problem, we analyzed the image characteristics of the region of interest and determined optimal parameters for segmentation. Then, we sequentially applied several image filters to the CT or MR images to obtain tissue contour curves, which were checked immediately by the operator and stored in the image processing computer. The 3 dimensional wire-frame image of the patient head was easily displayd on the screen using tissue contour data. Secondly, we produced the solid model. The contour lines are printed on the wax clay plates with the same thickness as CT or MR slices. The plates are cut along the contour line and compiled to reconstruct the solid model. Finally, we fixed the solid model on the table and shaved with a small spatulas to performed surgical simulation under a neurosurgical navigator, "CANS Navigator". The procedures were recorded with the navigator and replayd at the actual operation.