中文摘要：

为了实现胸部多模态医学图像的自动配准，提出了一种基于层次B样条自适应自由变形法和梯度下降法的配准方法。首先采用GVF Snake与Canny算子实现边缘提取，并自动配对特征点；接着，采用矩主轴法对多模医学图像进行全局粗配准；最后，基于层次B样条自适应自由变形法对多模态医学图像进行自动细配准，并且采用梯度下降法以及最大信息熵准则加速求自由变形系数。实验证明该方法不仅效率高，而且配准效果好。

英文摘要：

In order to realize the automatic registration of thorax multimodal medical images, this paper proposed an image registration method based on hierarchical adaptive free-form deformation and gradient descent. Firstly, extracted the edge of thorax by GVF Snake algorithm and Canny operator, and matched feature points automatically. Then, modeled the global coarse registration of thorax muhimodal medical images by principal axes algorithm. Finally, realized the local fine registration of thorax multimodal medical images by a free-form deformation（FFD） based on hierarchical B-splines. Moreover, generated the FFD parameters rapidly by gradient descent and maximization of mutual information. Experiments demonstrate the good performance of the proposed method.