电子射野影像仪与锥形束CT用于胸部肿瘤 影像引导放疗的比较研究

目的 比较电子射野影像仪(EPID)和锥形束CT(CBCT)用于胸部肿瘤影像引导放疗,在工作流程和发现患者摆位误差两个方面为临床选择不同影像引导放疗工具提供依据。方法 选择2007年3月至2008年1月在我院接受根治性放疗的17例胸部恶性肿瘤患者(包括肺癌、食管癌和胸腺瘤),每位患者每周分别行千伏锥形束CT(KVCBCT)和EPID影像引导分析各1次。1例患者(肺癌)在完成2次KVCBCT在线引导放疗后自动退出研究,共有16例患者进入最终研究分析。结果 16例患者共获取81对EPI和CBCT影像。采用CBCT引导放疗系统时,患者的治疗总时间较采用EPID引导放疗系统时增加1.2 min。采用EPID引导放疗技术分析胸部肿瘤患者的摆位误差,患者在左右(LR)、头脚(SI)和前后(AP)3个方向上的摆位误差分别为:(-0.1±3.2)mm、(1.3±3.7)mm和(-0.2±3.1)mm。计算临床靶体积(CTV)到计划靶体积(PTV)的预留边界,CTV到PTV的预留边界应设定为10mm。采用KVCBCT引导放疗技术分析这部分患者的摆位误差,LR、SI和AP 3个方向上的摆位误差分别为:(0.1±4.6)mm、(0.6±4.0)mm和(-0.9±4.6)mm,CTV到PTV的预留边界应设定为12mm。结论 与EPID相比,采用CBCT引导放疗系统没有明显延长治疗时间,但增加了发现摆位误差的能力,建议有条件的单位选择CBCT进行胸部肿瘤患者的影像引导放疗或摆位误差分析。

Comparison between electronic portal imaging device (EPID) and cone-beam CT (CBCT) in image-guided thoracic tumor radiotherapy

Objective To compare the set-up error detected by electronic portal imaging device (EPID) with cone-beam CT (CBCT) for patients with thoracic tumor, and to explore the impact on the workflow of different imaging-guided device. Methods From Mar 2007 to Jan 2008, 17 patients with pathologically confirmed thoracic tumor, including lung, esophagus and thymoma, were included in this study. Each patient received both EPID based-CBCT based_imaging_guided analysis once a week. Results A total of 81 pairs of EPI and CBCT scan from 16 patients except one case were obtained during treatment. Compared with EPID based_imaging guided analysis, CBCT based_imaging guided analysis did not increase the total treatment time significantly. The average set-up error of EPID was (-0.1±3.2), (1.3±3.7) and (-0.2±3.1)mm in the left-right (LR),superior-inferior (SI) and anterior-posterior (AP) directions, respectively (±SD). But the average set-up error,while that of CBCT was (0.1±4.6),(0.6±4.0) and (-0.9±4.6)mm in the LR, SI and AP directions, respectively. Conclusions CBCT would be better than EPID in detecting set-up error of the thoracic tumor patients. Compared with EPID, CBCT based_imaging guided analysis could not influence the workflow of radiotherapy significantly. CBCT based_imaging guided analysis might be more efficient than EPID.