机载影像系统分析体部肿瘤放疗摆位误差的临床观察

Clinical Observation of the Setup Errors by on Board Imager in Body Tumors Treated with Radiotherapy

目的通过直线加速器机载影像系统分析体部肿瘤放疗期间产生的摆位误差,测量临床靶体积(CTV)到计划靶体积(PTV)边界的大小。方法应用直线加速器治疗55例体部肿瘤。放疗前获取锥形束CT(CBCT)图像,将该图像与计划CT图像相匹配,计算平移和旋转误差。结果胸部肿瘤平移误差在左右(x)方向、头脚(y)方向、前后(z)方向分别为(-0.309 8±3.706 7)mm、(0.500 1±5.958 7)mm、(0.161 0±4.512 6)mm;腹部肿瘤分别为(-0.392 7±2.601 2)mm、(0.872 1±5.600 1)mm、(0.110 3±3.297 8)mm;旋转误差在胸部和腹部肿瘤分别为(0.218 3±1.502 8)°、(-0.198 9±1.596 6)°。结论 CTV到PTV胸部肿瘤外放边界值在x方向、y方向、z方向分别为7 mm、11 mm、8 mm为宜;腹部肿瘤分别为5 mm、10mm、6 mm为宜,可以包括90%的摆位误差。

Objective To analyze the setup errors by a linear accelerator on board imager in body tumors treated with radiotherapy, measuring the clinical target volume （CTV） to planning target volume （PTV） the size of the border. Methods The application of linear accelerators to treat 55 patients with body tumors. Radiotherapy for cone-beam CT （CBCT） images, the images and planning CT images to match, to calculate the translational and rotational errors. Results Chest tumor translation error on left-right （x）, head-feet （y）, before-after （z） direction were （ -0. 309 8 ±3. 706 7） mm, （0. 500 1 ±5. 958 7） mm, （0. 161 0±4. 512 6） mm, respectively; abdominal tumors were （ - 0. 392 7 ± 2.601 2） mm, （0. 872 1± 5. 600 1 ） mm, （0.110 3 ± 3. 297 8 ） mm, respectively. Rotation errors in the chest and abdominal tumors were （0.218 3± 1. 502 8）°, （ _ 0. 198 9 ± 1. 596 6）°, respectively.Conclusion For the chest tumor, the appropriate CTV to PTV putting boundary value in the x direction, y direc- tion and z direction are 7 ram, 11 mm, 8 mm, respectively; abdominal tumors, 5 mm, 10 mm, 6 mm, respective- ly; it can include the setup errors of 90%.