固定治疗床值摆位技术在胸腹部肿瘤IMRT中的应用

目的：探讨采用固定治疗床值摆位技术降低胸腹部肿瘤调强放射治疗摆位误差的方法。方法：应用瓦里安Trilogy直线加速器治疗胸腹部肿瘤患者30例，每位患者在首次治疗前均行CBCT扫描，并与计划系统的定位CT图像进行匹配，获取首次摆位后、摆位误差纠正后X（左右）、Y（头足）、Z（腹背）三个方向上的治疗床值，该数值为旋转容积调强照射提供了移床的精确数据。对所有患者第10次治疗前再行CBCT，与定位CT图像匹配，计算并分析第10次的摆位误差。结果：30例患者在X轴、Y轴、Z轴方向的平均摆位误差分别为（2．36±1．25）mm、（3．03±1．47）mm、（2．47±0．97）mm。结论：应用固定床值摆位技术明显降低了X和Z方向的误差。同时，摆位时以治疗床值的作为参考，简化了摆位过程，增加了患者的舒适度。

Application of The Placement Technique by Fixed Accelerator Treatment Table Values in Radiotherapy of Thorax and Abdomen Tumors

Objective：To analyze the placement technique by the fixed Accelerator treatment table values in radiotherapy of thorax and abdomen malignant, to probe the method for reduing setup error. Methods：thirty patients with thorax and abdomen malignant received radiotherapy by Varian Trilogy linear accelerator. CBCT images were collected before radiation therapy for each patient, and were dimensionally matched with planned CT images in planning system, then analyzed treatment table values in X （left-right）,Y （ventral-dorsal）,Z cranial-caudal）directions after initial setup and after re-positioning, which provided a constant couch shifting data which respond to line couchs in X,Y,Z in shifting directions. CBCT images were collected after the tenth radiation therapy for every patient, matched with planned CT images, then the tenth setup errors were calculated and evaluated. Results：The average setup errors of 30 patients in the X axis, the Y axis,the Z axis were 2.36 mm,3.03 mm,2.47 mm respectively. Conclusions： The application of the placement technique by the fixed Accelerator treatment table values reduced the setup errors in X and Y directions, significantly improved the positioning accuracy of radiotherapy.In addition,simplified the placement process, led to comfortable of the patients.