利用薄膜描记比对方法改善颅内肿瘤靶区勾画的初步评价

A Preliminary Study of Portraying and Verifying of MRI on Thin Film to Enhance Accuracy of Target Area Delineation in Intracranial Tumors

目的探讨薄膜描记比对方法改善颅内肿瘤靶区勾画的可行性。方法在MRI矢状位确定颅内肿瘤病灶具有代表性的3个层面并测量这3个层面至矢状正中层面的距离Sd1、Sd2、Sd3,在一张薄膜上用细线笔描记这3个层面的颅骨表面轮廓与肿瘤病灶轮廓;根据Sd1、Sd2、Sd3数值在重建矢状位CT影像中找到相对应的3个层面,通过调节图像缩放功能以及微调头颅前倾后仰角度,使得2幅图像的颅骨表面轮廓完全重合。冠状位层面的匹配过程大致类推。矢状位切面图与冠状位切面图各取60套,将治疗计划的肿瘤靶区轮廓与薄膜描记的MRI肿瘤病灶轮廓比对验证,分别测出两者在各方向的差异。结果 2种方法在矢状位的差异:前后方向(1.25±0.56)mm,头脚方向(1.37±0.42)mm;在冠状位的差异:左右方向(1.82±0.89)mm,头脚方向(2.26±0.86)mm;大于3 mm差异者,矢状位的前后与头脚方向均为0.00%,而冠状位的左右方向为0.00%,冠状位的头角方向为6.67%。结论薄膜描记比对方法可以改善颅内肿瘤靶区的勾画准确性。

Objective To discuss the feasibility of portraying and verifying of MRI on thin film to enhance accu- racy of target area delineation in intracranial tumors. Methods The 3 typical planes of intracranial tumor on sagittal site MRI imaging were located,the distances between these 3 planes and the median sagittal plane （Sd1,Sd2, Sd3 ） were measured respectively, and the outlines of skull bone and tumor on a thin film were portrayed by fine pencil, and the corresponding plane on planning CT were found according to Sd1, Sd2, Sd3. these two skull outlines overlap- ping as much as possible by shrinking/enlarging pictures or raising/bending head were made, and the outlines of GTV and portrait of MRI tumor outlines on fihn were compared. Coronal plane verification was done in a similar way. Results The variances of two outlines in the sagittal site were ： vertical （ 1. 25 ±0. 56 ） ram, longitude （ 1.37 ±0.42） mm, the variances of two outlines in the coronal site were ： latitude （ 1.82 ±0.89 ） mm, longitude （2. 26±0.86） mm,variance over 3 mm in the sagittal vertical and longitude,was 0.00% in the coronal latitude, and 6.67% in the coronal longitude. Conclusion The portraying and verifying of MRI on thin film may enhance accuracy of target area delineation in intracranial tumors.