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用平滑薄板样条实现医学图象的弹性配准

张煜1, 刘哲星1, 郝立巍1, 李树祥1(第一军医大学生物医学工程系医学图象重点实验室,广州 510515)

摘 要
医学图象弹性配准是医学图象处理的一个重要研究方向.目前采用的方法多是手动选择对应标记点,然后用薄板样条插值方法计算配准变换.为了降低对应点的选取误差对配准准确性的影响,并克服手动选点操作繁杂、耗时大的问题,给出了一种准确、快速、鲁棒性好的配准方法.即对薄板样条插值方法进行平滑处理,并在此基础上采用一种半自动标记点选择方法.运用此方法进行医学图象的弹性配准,得到了理想的结果.实验表明,该方法能有效减弱了对应点位置误差对配准结果产生的影响,并能较方便地选择对应点集
关键词
Medical Image Elastic Registration Using Smoothing Thin-Plate Spline

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Abstract
Medical image elastic registration is an important subject in medical image processing. Previous work has concentrated on selecting the corresponding landmarks manually and then using thin plate spline interpolating to gain the elastic transformation. However, the landmarks extraction is always prone to error, which will influence the registration results. Localizing the landmarks manually is also difficult and time consuming. In order to solve these problems, a novel method is proposed in this paper. By smoothing the thin plate spline interpolation functions, the influence of the landmarks error can be decreased effectively. And basing on the process, a semi automatic method is used to extract the landmarks, which can simplify the selection for points. Combining these two steps, an exact, fast and robust registration approach is obtained. The approach is composed of two steps. First, it searches the contours and makes them discrete to gain the corresponding landmarks. Then by interpolating images with the smooth thin plate spline, the registration images are obtained. To validate the effect, series experiments are implemented. The experiments show that the novel method can reduce the influence of the landmarks error and gain the satisfactory registration results. In this approach, the smooth parameter is an important factor, which must be selected carefully. The principle for determining the parameter is presented in the end of this paper.
Keywords

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