| 摘要: |
| ［摘要］ 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%。 |
| 关键词: 鼻咽癌 调强放疗 锥形束CT 图像引导放疗 摆位误差 |
| DOI：10.3969/j.issn.1674-3806.2014.10.03 |
| 分类号:R 739.6 |
| 基金项目:广西卫生厅科研课题（编号：Z2013370）；广西科技厅科研课题（编号：0235024-10） |
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| Interfractional and intrafractional errors assessed by daily cone-beam computed tomography in nasopharyngeal carcinoma treated with intensity-modulated radiation therapy |
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LU He-ming, FENG Guo-sheng, CHEN Jia-xin, et al.
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Department of Radiation Oncology, Medical Oncology, the People′s Hospital of Guangxi Zhuang Autonomous Region, Nanning 530021, China
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| Abstract: |
| ［Abstract］ Objective To assess interfractional and intrafractional errors and to estimate appropriate margins for planning target volume(PTV) by using daily cone-beam computed tomography(CBCT) guidance in nasopharyngeal carcinoma(NPC) treaded with intensity -modulated readiation therapy(IMRT).Methods Daily pretreatment and posttreatment CBCT scans were acquired separately after initial patient setup and after the completion of each treatment fraction in 10 patients treated with IMRT. Online corrections were made before treatment if any translational setup error was found. Interfractional and intrafractional errors were recorded in the right-left(RL), superior-inferior(SI), and anterior-posterior(AP) directions.Results For the translational shifts, the interfractional errors >2 mm occurred in 21.7% of measurements in the RL direction, 12.7% in the SI direction, and 34.1% in the AP direction, respectively. Online correction resulted in 100% of residual errors ≤2 mm in the RL and SI directions, and 95.5% of residual errors ≤2 mm in the AP direction. No residual errors >3 mm occurred in the three directions. For the rotational shifts, significant reduction was found in the magnitudes of residual errors compared with those of interfractional errors. A margin of 4.9 mm, 4.0 mm, and 6.3 mm was required in the RL, SI, and AP directions, respectively, when daily CBCT scans were not performed. With daily CBCT, the margins were reduced to 1.2 mm in all directions.Conclusion Daily CBCT guidance is an effective modality to improve the accuracy of IMRT for NPC. The online correction could result in a 70%～81% reduction in margin size. |
| Key words: Nasopharyngeal carcinoma Intensity-modulated radiation therapy Cone-beam computed tomography Imaged guided radiation therapy Setup error |
