BACKGROUND Lung cancer is a leading cause of morbidity and mortality worldwide. Radiotherapy for lung cancer is beneficial in both the radical and palliative settings, and technologic advances in recent years now afford an opportunity for this treatment to be more targeted than ever before. Although the delivery of more accurate forms of radiotherapy has minimized the risks of side-effects, how to utilize this treatment to optimize outcomes remains questionable. This study aimed to evaluate the accuracy of cone beam computed tomography (CBCT) image registration used in image-guided radiotherapy, providing reasonable guidance for clinic application of CBCT in lung cancer. METHODS A total of 53 patients with lung carcinoma including 34 central and 19 peripheral lesions were collected in this study. Varian-IX linear accelerator on-board imaging (OBI) system was used to acquire CBCT scans in three-dimensional (3D) conformal radiotherapy before delivery. Different regions (whole lung/target/vertebrae/ipsilateral structure) were manually registered, and the position deviation and the registration time were analyzed. RESULTS It was suggested that 34 cases belonged to central type and 19 cases belonged to peripheral type. The volume of left lung and right lung was 1242.98 ± 452.46 cc, 1689.69 ± 574.31 cc, respectively. Tumor size was 6.65 ± 3.87 cm in diameter, and 129.67 ± 136.48 cc in volume. The percentage of left lung and right lung was 6.17 ± 1.24%, 4.74 ± 0.38%, respectively. The position deviation value and absolute value of image registration methods of X, Y and Z axis were not significant (P > 0.05). However, registration time (s) between whole lung registration group, tumor registration group, vertebral body registration group, affected lung registration group, and artificial registration group, was 3.651 ± 0.867 s, 1.144 ± 0.129 s, 1.226 ± 0.126 s, 2.081 ± 0.427 s, 179.491 ± 71.975 s, respectively. The differences were significant (P < 0.05). The registration differences between small tumor group and large tumor group were not statistically significant (P > 0.05). CONCLUSION The automatic image matching of OBI is accuracy and high reliability in recognition of offset error. Registering body or ipsilateral structure is recommended to be used in CBCT for lung cancer.

中文翻译：

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肺癌放疗中不同感兴趣区域图像配准方法的比较评价

背景技术肺癌是全世界发病率和死亡率的主要原因。肺癌的放射治疗对于根治性和姑息性治疗都是有益的，近年来的技术进步现在为这种治疗提供了比以往任何时候都更有针对性的机会。尽管提供更准确的放射治疗形式已经最大限度地降低了副作用的风险，但如何利用这种治疗来优化结果仍然存在疑问。本研究旨在评价锥形束计算机断层扫描（CBCT）图像配准在图像引导放疗中的准确性，为CBCT在肺癌的临床应用提供合理指导。方法收集53例肺癌患者，其中中心型病灶34个，周围型病灶19个。Varian-IX 直线加速器机载成像 (OBI) 系统用于在产前三维 (3D) 适形放疗中获取 CBCT 扫描。手动配准不同区域（全肺/目标/椎骨/同侧结构），并分析位置偏差和配准时间。结果 中心型34例，周围型19例。左肺和右肺的容积分别为1242.98±452.46cc、1689.69±574.31cc。肿瘤大小为直径6.65±3.87cm，体积129.67±136.48cc。左肺和右肺的百分比分别为6.17±1.24%、4.74±0.38%。X、Y、Z轴图像配准方法的位置偏差值和绝对值均不显着（P>0.05）。然而，全肺配准组、肿瘤配准组、椎体配准组、患肺配准组和人工配准组之间的配准时间分别为3.651±0.867s、1.144±0.129s、1.226±0.126s、2.081±分别为 0.427 秒、179.491 ± 71.975 秒。差异显着（P<0.05）。小肿瘤组与大肿瘤组配准差异无统计学意义（P > 0.05）。结论OBI自动图像匹配识别偏移误差准确、可靠性高。肺癌CBCT推荐使用配准身体或同侧结构。