基于水平集的三维放射治疗CT图像弹性配准

Level set motion-based elastic registration of 3D CT images in radiotherapy

目的:将基于水平集的图像弹性配准应用于放射治疗CT图像中,为精确评估患者肿瘤及危及器官变化过程及其累加剂量提供技术支持。方法:根据水平集进化理论,通过matlab软件编程,分别对宫颈癌患者与鼻咽癌患者放射治疗分次间的两组CT图像实施三维全自动的弹性配准。结果:宫颈癌患者配准前后对比显示,最小均方误差(MSE)减少55.1%,相关系数(CC)提高了5.3%;鼻咽癌患者配准前后对比显示,MSE减少32.1%,CC提高4.6%。结论:从配准前后差分图以及评价参数可见,该理论取得了较好的试验效果,但要真正应用到临床放射治疗中,需进一步探寻更精确的数学算法以模拟人体器官的运动。

Objective： To apply level set motion-based elastic registration method to radiotherapy CT image, then to provide technical support for the accurate evaluation of tumor and changing process of patients with endanger organ and its accumulative dose. Methods： Based on Vemuri’s level set motion method, we wrote the algorithm program using Matlab software and applied on two sets of 3D CT images from patients with cervical cancer and NPC for fully automatic elastic registration. Results： Comparing CT images before and after registration, for the cervical cancer patient, the minimum mean square error （MSE） decreased by 55.1%and correlation coefficient （CC） increased by 5.3%. For the NPC patient, MSE decreased by 32.1%and CC increased by 4.6%. Conclusion： From the image difference and evaluation parameters, the efficacy of level set motion-based elastic registration method was preliminarily demonstrated. In order to apply this method to clinical radiotherapy, dit needs to find a more accurate mathematical algorithm further in order to compute human anatomy deformation through image motion.