乳腺癌保乳术后调强放射治疗在CT图像引导下的摆位误差分析

Analysis of Setup Error of Intensity-Modulated Radiation Therapy Guided by CT Images After Breast-Conserving Surgery for Breast Cancer

目的探讨乳腺癌保乳术后调强放射治疗采用CT图像引导的摆位误差。方法选取我院18例乳腺癌保乳术后接受适形调强放射治疗的患者,应用CTVision图像引导放疗系统,在三维方向上的摆位误差方面,使用电子射野影像系统对第一次放疗、第5次放疗及第10次放疗摄取调强放疗的正、侧位共108幅射野图像,将其与正、侧位标准射野数字重建图像进行比较,测得摆位误差。结果记录加速器下所有患者在X轴方向(左右)、Y轴方向(头脚)及Z轴方向(前后)的第1次放疗、第5次放疗和第10次放疗的摆位误差,分别为X1(2.6±0.8)mm、Y1(2.8±0.7)mm、Z1(1.7±0.7)mm;X2(3.2±0.5)mm、Y2(3.6±0.8)mm、Z2(2.0±0.4)mm;X3(3.4±0.9)mm、Y3(3.8±0.6)mm、Z3(2.4±0.5)mm。X1、Y1分别与Z1比较,X2、Y2分别与Z2比较,X3、Y3分别与Z3比较,其差异均具有统计学意义(P<0.05)。结论应用CT图像引导的调强放疗在乳腺癌保乳术后患者中可以使摆位误差控制在放疗可接受误差范围之内,值得临床推广应用。

Objective To explore the setup error guided by CT image of the postoperative intensitymodulated radiation therapy for breast-conserving surgery of breast cancer. Methods Eighteen patients who received conformal intensity modulated radiation therapy after their breast-conserving surgery for breast cancer were selected, CTVision image-guided radiation therapy system was applied, in terms of the setup error in three dimensional directions, electronic beam imaging system was used for the first, fifth and the tenth radiotherapy, altogether 108 frontal and lateral radiation field images were captured, and compared them with the frontal and side standard beam digital reconstruction images, then beam setup error was measured. Results Record all the setup errors of the patients in the X axis direction（left and right）, Y axis direction（head to foot）and the Z axis direction（front and back）of their the first, fifth and tenth radiotherapy with accelerator, which are respectively： X1（2.6±0.8）mm, Y1（2.8±0.7）mm, Z1（1.7±0.7）mm; X2（3.2±0.5）mm, Y2（3.6± 0.8）mm, Z2（2.0±0.4）mm; X3（3.4±0.9）mm, Y3（3.8±0.6）mm, Z3（2.4±0.5）mm. X1 and Y1, X2 and Y2, as well as X3 and Y3 were compared with Z1, Z2 and Z3 respectively, results showed that their differences were statistically significant（P〈0.05）. Conclusion The application of CT image guided intensity-modulated radiotherapy in breast cancer in postoperative patients can ensure that the setup error is within acceptable error range of radiotherapy, which is worthy of clinical popularization and application.