应用模拟定位机测量食管癌调强放疗中的摆位误差

Evaluation of set-up errors for patients for esophageal carcinoma treated with Intensity modulated radiation therapy by simulator

目的:利用模拟定位机匹配功能测量食管癌调强放疗的摆位误差。方法:通过对171例食管癌患者计划系统生成的数字重建放射图(DRR)和模拟机拍摄的正、侧位图像的骨性标记进行比较,测出患者在左右(X轴)、头脚(Y轴)、前后(Z轴)方向误差,并对误差大于0.3cm进行调整。结果:患者左右、头脚、前后误差分别为0.19±0.24cm、0.27±0.34cm、0.27±0.25cm,其中左右方向需要调整的患者有40例,占总体的23.4%,头脚方向需要调整的患者有52例,占30.4%,前后方向需要调整的患者有64例,占37.4%。结论:模拟机图像匹配功能的应用,能对患者摆位误差进行及时的调整,从而提高实际摆位精度,同时为正确设定计划靶体积(PTV)提供了依据。

ObjeetiveTo evaluate setup error by Varian Acuity simulator Methods 171 patients for esophageal carcinoma treated with Intensity modulated radiation therapy were included in this study. DRRs of each patient were compared with portal images from simu- lator and set - up errors were recorded and analyzed. Patients should be adjusted when setup error exceeded 0. 3 cm. Results The setup errors in Right - Left, Cranial - Caudal and Anterior - Posterior directions were （0. 19 ＋0. 24） cm, （0. 27 ＋0. 34） cm and （0. 27 ＋ 0. 25 ） cm 40 patients should be adjusted in Right - Left direction and 52 patients in Cranial - Caudal direction , 64 patients in Anterior -Posterior direction. And the margins from CTV or ITV to PTV were given. Conclusion Measurement of setup error before radiation delivery using simulator with correction could greatly improve the patient setup precision and may guide optimal PTV designing.