下颌骨CT三维重建中阈值分割的改进及应用

Improving Threshold Segmentation in 3D Reconstruction of Mandible CT Image

目的对下颌胃CT三维重建中阈值分割方法的不足进行改进,比较改进后的方法与传统方法在下颌骨图像分割中的差别。方法将12例健康志愿者下颌骨CT数据导入Mimics 10.01,分别用改进方法和传统方法进行图像分割。改进方法首先使用较窄的阈值范围(调节阈值上、下限值至能分离出下颌骨的最宽阈值)进行分割,然后利用膨胀运算弥补因阈值范围过窄造成的边界信息损失,得到一个近似分割结果,再结合逻辑运算及区域生长工具,得到精确的分割结果。测量两种方法分割所花时间的平均值,并用Geomagic Studio 11.0比较其重建后结果间的差异。结果改进后的方法成功率为91.67%(11/12);分割时间为(319.7±125.3)s,小于传统方法的分割时间〔(1 261.3±427.3)s,P<0.05〕。以传统方法重建结果作为参照目标,改进后方法朝外的偏差为(0.066±0.011)mm,朝内的偏差为(0.070±0.008)mm,误差远小于肉眼分辨距离。能分离出下颌骨的最宽阈值范围下限为(507.72±100.31)HU,上限为(1 133.33±47.57)HU。结论本研究提出的阈值分割改进方法能明显提高阈值分割方法分割下颌骨的效率。

Objective To develop a new threshold segmentation method for mandible image segmentation.Methods CT data of 12 volunteers were exported into Mimics 10.01.An improved method usinga narrowed threshold range（the maximum threshold range that can segment mandible without manual efforts）was developed in3 Dreconstruction,and compared with the traditional method. We used dilation operations to make up the information loss of image borders,by which we obtained an approximate segment result.A precise segment resultwas eventually arrived with the help of logical operations and region growing.We compared mean time consumptions of the two methods,as well as their 3Dreconstruction results using Geomagic Studio 11.0.ResultsThe new method generated a success rate of 91.67%（11/12）,with a mean time consumption of（319.7±125.3）s.The traditional method took much longer time〔（1 261.3±427.3）s,P〈0.05〕than the new method.Compared with the reconstruction results of traditional method,the new method had an outward deviation of（0.066±0.011）mm and an inward deviation of（0.070±0.008）mm.Such deviations were less than the minimum distance that a naked eye can discern.The lower limit of the widest threshold range which mandible could be isolated was（507.72±100.31）HU,while the upper limit was（1 133.33±47.57）HU.Conclusion The new method we proposed can improve the efficiency of threshold segmentation of mandible.