利用距离变换实现CT图象中软组织显示

3D Soft-Tissue visualization Scheme of CT Images via Distance Transformation

基于距离变换的软组织显示方法 ,由分割、距离变换、剥皮和体绘制 4个步骤组成 .为加快运算速度和满足实时交互的需要 ,在进行三维医学 CT图象内部软组织显示时 ,采用了一种新的三维欧氏距离变换算法和基于体绘制的三维数据场多表面显示方法 .实验结果表明 ,该方法能够清晰地再现皮下血管、肌肉与骨骼的空间解剖关系 。

In this paper, a new 3D soft tissue display scheme is proposed, which consists of four steps: image segmentation, distance transformation, peeling operation and volume rendering. Firstly, an image segmentation method is adopted to detect the contour of skin, and a new binary output image is produced. Secondly, to reduce the computation time, a new 3D Euclidean distance transformation algorithm was adopted to compute the distance map of the medical image. Thirdly, the image data of the scarfskin and subcutaneous fat of the specified depth is removed through peeling operation. Finally, in order to meet the requirement of real time interaction in the medical application, a new multi surface visualization method was adopted, whose rendering time is reduced by only projecting the voxels near the boundaries between the different tissues. Meanwhile, it improves the visualization quality by computing the normal of the point where the ray crosses the iso surface in the projected voxel. This scheme was implemented in the 3D medical image process and analysis system developed by our lab to display the soft tissue of the CT images. The experiment results show that the anatomical structure among the blood vessel, flesh and bone can be visible clearly, and this method has important practical value in clinical diagnosis.