Quantification of intra-fraction changes during radiotherapy of cervical cancer assessed with pre- and post-fraction Cone Beam CT scans
Quantification of intra-fraction changes during radiotherapy of cervical cancer assessed with pre- and post-fraction Cone Beam CT scans
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DOI：
10.1016/j.radonc.2015.08.034
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发表时间：
2015-12-01
影响因子：
5.7
通讯作者：
Hoogeman, Mischa S.
中科院分区：
文献类型：
--
作者：
Heijkoop, Sabrina T.;Langerak, Thomas R.;Hoogeman, Mischa S.
背景和目的：随着调强放射治疗（IMRT）和影像引导的计划日策略的引入，宫颈癌的治疗对分次内不确定性变得更加敏感。在这项研究中，我们量化的子宫颈，子宫形状，膀胱和直肠填充，和患者设置使用前和后馏分CBCT scans.Materials和方法：共632 CBCT扫描进行了分析，为16例大尖的子宫位移（>2.5厘米）测量在空和全膀胱CT扫描的分数内变化。在所有扫描中，均描绘了膀胱、宫颈和直肠。对于直肠和膀胱，评估了部分内体积变化。通过非刚性对齐分割前子宫颈与分割后CBCT中的子宫颈，获得系统性子宫颈分割内移位。通过使用骨解剖结构严格对齐CBCT前后，获得了骨折内患者设置的变化。结果：分割前和分割后CBCT扫描之间的平均时间为20.8分钟。宫颈-子宫的组平均分割内位移平均值为0.1 +/- 1.4/1.8 +/- 1.5/-2.8 +/- 1.8组间平均第5和第95百分位组内位移分别为-2.3，2.1/-0.8，4.9/-5.8，0.5（LR/CC/AP）mm。在患者设置的分数内变化分别为1.3/0.4/0.6和1.4/1.0/1.1毫米（LR/CC/AP），系统和随机changes.Conclusion：分数内子宫颈运动可以是相当大的，应该考虑使用适当的PTV边缘。(C)2015爱思唯尔爱尔兰有限公司版权所有。
Background and purpose: With the introduction of Intensity Modulated Radiotherapy (IMRT) and image-guided plan-of-the-day strategies, the treatment of cervical cancer has become more sensitive to intra-fraction uncertainties. In this study we quantified intra-fraction changes in cervix-uterus shape, bladder and rectum filling, and patient setup using pre- and post-fraction CBCT scans.Materials and methods: A total of 632 CBCT scans were analyzed for 16 patients with large tip-of-uterus displacement (>2.5 cm) measured in an empty and full bladder CT scan. In all scans, the bladder, cervixuterus, and rectum were delineated. For rectum and bladder, intra-fraction volume changes were assessed. Systematic cervix-uterus intra-fraction displacements were obtained by non-rigidly aligning the pre-fraction cervix-uterus to that in the post-fraction CBCT. Intra-fraction patient setup changes were obtained by rigidly aligning pre- and post-CBCTs using the bony anatomy.Results: The mean time between pre- and post-fraction CBCT scan was 20.8 min. The group-mean intrafraction displacements averaged over the cervix-uterus were 0.1 +/- 1.4/1.8 +/- 1.5/-2.8 +/- 1.8 (LR/CC/AP) mm. The group-mean 5th and 95th percentile intra-fraction displacements were -2.3,2.1/-0.8,4.9/-5.8,0.5 (LR/CC/AP) mm. There was a significant correlation between bladder inflow rate and cervixuterus motion (r = 0.6 and p < 0.01). Intra-fraction changes in patient setup were 1.3/0.4/0.6 and 1.4/1.0/1.1 mm (LR/CC/AP), for systematic and random changes, respectively.Conclusion: Intra-fraction cervix-uterus motion can be considerable and should be taken into account using appropriate PTV margins. (C) 2015 Elsevier Ireland Ltd. All rights reserved.