宫颈癌自适应放疗中基于自配准与图谱库的自动勾画比较

Evaluation of the auto-segmentation based on self-registration and Atlas in adaptive radiotherapy for cervical cancer

目的分析MIM软件在宫颈癌自适应放疗中基于自配准与图谱库的自动勾画的可行性与准确性。方法选取60例宫颈癌患者的CT图像及勾画结果建立Atlas模板库。随机选取15例宫颈癌患者初次计划CT (pCT)与重新计划CT (rCT),由资深临床医师勾画CTV和危及器官。分别以刚性和形变两种配准方式将pCT的勾画传送到rCT图像上;并对各rCT图像行基于Atlas模板库的自动勾画,统计3种方法所需时间。利用Dice相似性系数(DSC)、交叉指数(OI)、Hausdorff平均距离(AHD)、质心距离(DC)评价勾画结果,并进行单因素方差分析。结果Atlas组、刚性组和形变组完成1例所需平均时间分别为89.2、22.4、42.6 s。对于CTV和直肠的DSC、OI和AHD,刚性组和形变组与Atlas组之间不同(P<0.001),小肠的OI在刚性组和形变组与Atlas组之间有不同,CTV的DSC平均值分别为0.89(刚性组和形变组)、0.76(Atlas组)。对于膀胱、盆骨和股骨头,形变组的勾画结果最优。结论形变组的勾画结果优于刚性组和Atlas组,3种勾画方式均能快速地完成靶区和危及器官的自动勾画。

Objective To evaluate the accuracy and validate the feasibility of auto-segmentation based on self-registration and Atlas in adaptive radiotherapy for cervical cancer using MIM-Maestro software. Methods The CT scan images and delineation results of 60 cervical cancer patients were obtained to establish the Atlas template database. The planning CT (pCT) and replanning CT (rCT) images were randomly selected from 15 patients for the contouring of clinical target volume (CTV) and organs at risk (OAR) by an experienced radiation oncologist. The rCT images of 15 patients were auto-contoured using Atlas-based auto-segmentation (Atlas group), and mapping contours from the pCT to the rCT images was performed by rigid and deformable image registration (rigid group and deformable group). The time for the three methods of auto-segmentation was also recorded. The similarity of the auto-contours and reference contours was assessed using dice similarity coefficient (DSC), overlap index (OI), the average hausdorff distance (AHD) and the deviation of centroid (DC), and the results were statistically compared among three groups by using one-way analysis of variance. Results The mean time was 89.2 s, 22.4 s and 42.6 s in the Atlas, rigid and deformable groups respectively. The DSC, OI and AHD for the CTV and rectum in the rigid and deformable groups significantly differed from those in the Atlas group (all P<0.001). In the rigid and deformable groups, the OI for the intestine significantly differed from that in the Atlas group. The mean DSC for CTV was 0.89 in the rigid and deformable groups, and 0.76 in the Atlas group. The optimal delineation of the bladder, pelvis and femoral heads was obtained in the deformable group. Conclusions All three methods of auto-segmentation can automatically and rapidly contour the CTV and OARs. The performance in the deformable group is better than that in the rigid and Atlas groups.