Assessment by a deformable registration method of the volumetric and positional changes of target volumes and organs at risk in pharyngo-laryngeal tumors treated with concomitant chemo-radiation
Assessment by a deformable registration method of the volumetric and positional changes of target volumes and organs at risk in pharyngo-laryngeal tumors treated with concomitant chemo-radiation
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DOI：
10.1016/j.radonc.2010.03.007
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发表时间：
2010-05-01
影响因子：
5.7
通讯作者：
Gregoire, Vincent
中科院分区：
文献类型：
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作者：
Castadot, Pierre;Geets, Xavier;Gregoire, Vincent
目的：头颈部肿瘤放射治疗(RT)过程中会发生解剖学变化。本研究旨在量化大体肿瘤体积(GTV)、临床靶区体积(CTV)和危险器官(OAR)的体积和位置变化。采用解剖(CT)和功能成像(FOG-PET)显示GTV。材料与方法：对10例H&N肿瘤患者行放疗。增强CT和FOG-PET分别在放疗前和放疗期间进行，平均剂量分别为14.2、24.5、35.0和44.9Gy4个剂量。手动勾画基于CT的GTV，使用基于梯度的分割方法分割基于PET的GTV。使用一致且可重现的指南，在治疗前CT上手动描绘治疗前预防性剂量CTV。采用基于可变形配准的自动等值线重新绘制方法，获得预防性治疗后的CTV。对于治疗剂量的CTV，在相应的GTV周围施加5 mm的边缘。在治疗前CT上手动勾画腮腺和颌下腺等桨叶。每一次治疗CT上的桨是使用预防性CTV的方法自动描绘的。结果：在体积变化方面，基于CT和基于PET的原发肿瘤GTVS分别平均下降3.2%和3.9%/治疗日(TD)，结节GTVS平均下降2.2%/TD。这导致基于CT和基于PET的治疗性CTV分别下降了2.4%和2.5%/TD。基于CT和PET的预防性肿瘤CTV分别平均下降0.7%和0.5%/TD。CT和基于PET的体积之间的体积收缩没有差异。同侧和对侧腮腺的平均下降率分别为0.9%和1.0%。同侧颌下腺平均收缩1.5%，对侧颌下腺平均收缩1.3%。在位置变化方面，基于CT的GTV显示出1.3 mm的侧移，基于PET的GTV显示出3.4 mm的后移，结节GTV显示出1.0 mm的内移，转化为治疗性CTV的平行移位。同侧预防性结节CTV内移1.8 mm。同侧腮腺内移3.4 mm。同侧颌下腺内侧移位1.7 mm，上移2.7 mm。对侧颌下腺仅有1.7 mm的上移量。结论：在同步放化疗过程中，电视和桨的体积和位置发生了变化，提示患者在治疗期间重新成像和可能重新计划的适应策略是值得评估的。(C)2010爱思唯尔爱尔兰有限公司。保留所有权利。放射治疗和肿瘤学95(2010)209-217
Purpose: Anatomic changes occur during radiation therapy (RT) for head and neck (H&N) tumors. This study aims at quantifying the volumetric and positional changes of gross tumor volumes (GTV), clinical target volumes (CTV), and organs at risk (OAR). Anatomic (CT) and functional (FOG-PET) imaging were used for the delineation of the GTVs.Materials and methods: Ten patients with H&N tumors treated by chemo-RT were used. Contrast-enhanced CT and FOG-PET were acquired prior and during RT following delivery of mean doses of 14.2, 24.5, 35.0, and 44.9 Gy. CT-based GTVs were manually delineated, and PET-based GTVs were segmented using a gradient-based segmentation method. Pre-treatment prophylactic dose CTVs were manually delineated on the pre-treatment CT using consistent and reproducible guidelines. Per-treatment prophylactic CTVs were obtained with an automatic re-contouring method based on deformable registration. For the therapeutic dose CTVs, a 5 mm margin was applied around the corresponding GTVs. OARs such as the parotid glands and the submandibular glands were manually delineated on the pre-treatment CT. OARs on the per-treatment CT were automatically delineated using the method used for prophylactic CTVs. The mean slopes of the relative change in volume over time and the mean displacements of the center of mass after 44.9 Gy were calculated for each volume.Results: Regarding volumetric changes, CT-based and PET-based primary tumor GTVs decreased at a mean rate of 3.2% and 3.9%/treatment day (td), respectively; nodal GTVs decreased at a mean rate of 2.2%/td. This led to a corresponding decrease of the CT-based and PET-based therapeutic CTVs by 2.4% and 2.5%/td, respectively. CT- and PET-based prophylactic tumor CTVs decreased by an average of 0.7% and 0.5%/td, respectively. No difference in volume shrinkage was observed between CT- and PET-based volumes. The ipsilateral and contralateral parotid glands showed a mean decrease of 0.9% and 1.0%/td, respectively. The ipsilateral and contralateral submandibular glands shrank at a mean rate of 1.5% and 1.3%/td, respectively. Regarding positional changes, CT-based GTVs showed a lateral shift of 1.3 mm, PET-based GTVs a posterior shift of 3.4 mm and the nodal GTVs a medial shift of 1.0 mm, translating into parallel shifts of the therapeutic CTVs. The ipsilateral prophylactic nodal CTV shifted medially by 1.8 mm. The ipsilateral parotid gland shifted medially by 3.4 mm. The ipsilateral submandibular gland showed a medial shift of 1.7 mm and a superior shift of 2.7 mm. The contralateral submandibular gland only showed a superior shift of 1.7 mm.Conclusions: Volumetric and positional changes in TVs and OARs were observed during concomitant chemo-RT suggesting that adaptive strategies, where patients are re-imaged and possibly re-planned during treatment, are worth evaluating. (C) 2010 Elsevier Ireland Ltd. All rights reserved. Radiotherapy and Oncology 95 (2010) 209-217