论文部分内容阅读
目的利用锥形束计算机断层扫描(CBCT)作为图像引导,评估鼻咽癌调强放疗中分次间和分次内误差并估算计划靶体积(PTV)合适的边界。方法选取接受根治性调强放疗的10例患者进行研究,每次放疗前后对患者进行CBCT。治疗前发现有摆位误差立即在线校正。分别对分次间和分次内左右、上下和前后方向的误差进行记录和分析。结果 >2 mm分次间误差在左右、上下和前后方向分别为21.7%、12.7%和34.1%。CBCT引导下的在线校正可使100%的残留误差在左右和上下方向≤2 mm,使95.5%的残留误差在前后方向的残留误差≤2 mm。三个方向没有>3 mm的残留误差出现。与分次间的误差相比机器旋转位移引起的残留误差显著减少。没有进行每日CBCT扫描,左右、上下和前后方向上外扩的边界分别为4.9 mm、4.0 mm和6.3 mm,每日进行CBCT扫描使各个方向的外扩边界降低到1.2 mm。结论每天CBCT引导是提高鼻咽癌调强放射治疗准确性的有效方式。CBCT引导下的在线校正可使各方向的外扩边界减少70%~81%。
Objective To evaluate the inter-sub-fractional and intra-fractional errors and to estimate the appropriate target volume (PTV) for nasopharyngeal carcinoma with cone beam computed tomography (CBCT) as an image guide. Methods Ten patients undergoing radical intensity modulated radiotherapy were enrolled in this study. CBCT was performed on patients before and after radiotherapy. Before treatment, it is found that the setting error is corrected online immediately. Separately and sub-sub-left and right, up and down and before and after the direction of error records and analysis. Results> 2 mm sub-level error in the left and right, up and down and front and rear directions were 21.7%, 12.7% and 34.1%. The CBCT-guided online calibration allows 100% residual error to be ≤2 mm in the left and right and up and down directions and 95.5% residual error in the fore and aft direction ≤ 2 mm. There are no residual errors of> 3 mm in all three directions. The residual error caused by the rotational displacement of the machine is significantly reduced compared to the error between the sub-orders. Without daily CBCT scans, the outboard boundaries were 4.9 mm, 4.0 mm and 6.3 mm in the up, down, and anteroposterior directions, respectively. Daily CBCT scans reduced the flared boundary in all directions to 1.2 mm. Conclusion Daily CBCT guidance is an effective way to improve the accuracy of IMRT. CBCT-guided online calibration can reduce the outward expansion boundary in all directions by 70% -81%.