摘要
目的探讨利用四维锥形束CT(4D-CBCT)监测食管癌精确放疗中的摆位误差,为勾画食管癌合理的计划靶区(PTV)提供依据。方法采用医科达Axesse直线加速器机载4D-CBCT对16例食管癌患者精确放疗前行扫描,系统自动重建图像并与治疗计划CT图像相匹配,获得患者在头脚(SI)、左右(LR)、前后(AP)方向上的摆位误差,经过自动校正后,再次行4D-CBCT扫描,并按照同样的匹配方式与计划CT进行配准,采集校正后三维方向上的摆位误差。结果 16例患者共获166次扫描。校正前,4D-CBCT图像在SI、LR、AP方向的摆位误差分别为(5.6±0.4)mm、(3.4±0.5)mm和(2.2±0.2)mm,经过校正后在SI、LR、AP方向的摆位误差分别为(1.6±0.2)mm、(0.2±0.1)mm和(0.3±0.2)mm。摆位误差调整前在LR、SI、AP方向上临床靶区(CTV)到PTV外放边界分别为7.3mm、9.4mm和7.6mm,调整后分别为3.0mm、4.6mm和2.5mm。结论利用4D-CBCT图像在治疗前进行误差校准,可以明显缩小摆位误差,更加准确地勾画食管癌PTV的范围,提高食管癌的放疗精度。
Objective To investigate the application of four dimension cone-beam CT（4D-CBCT） on accurate radiotherapy of esophageal cancer, and provide basis for delineation of planning torget volume（PTV）. Methods Sixteen patients with pathologically confirmed esophageal cancer were included in this study.Each patient received 4D-CBCT based imaging guided analysis once a week. Online CBCT scan,image registration and setup correction were performed before and immediately alter radiotherapy. The CBCT images were matched and compared with the images of planning CT automaticly and the setup errors were displayed in the superior-inferior （SI）, left-right（LR） and anterior-post（AP） directions respectively. The setup errors were corrected with remote control before the treatment. Results A total of 166 CBCT scan from 16 patients were obtained during treatment.Under the condition of non-correction, the error were （5.6±0. 4）mm, （3.4±0. 5）mm, （2. 2±0. 2）mm in the SI, LR and AP directions, respectively.When the tumor was corrected in every fraction, the error were （ 1.6±0. 2） mm, （ 0. 2±0. 1 ） mm, （ 0. 3±0. 2） mm respectively. The margins of target in the SI, LR and AP directions was 7. 3mm, 9.4mm, 7.6ram before correction and 3.0mm, 4. 6mm, 2. 5mm after correction. Conclusion The use of 4D-CBCT correction markedly reduce the impact of setup error. It is feasible to deliver the online image guided radiation for patients with esophageal cancer.
出处
《临床肿瘤学杂志》
CAS
2014年第11期1011-1014,共4页
Chinese Clinical Oncology
