Tan, W;
Wang, Y;
Yang, M;
Amos, RA;
Li, W;
Ye, J;
Gary, R;
... Hu, D; + view all
(2018)
Analysis of geometric variation of neck node levels during image-guided radiotherapy for nasopharyngeal carcinoma: recommended planning margins.
Quantitative Imaging in Medicine and Surgery
, 8
(7)
pp. 637-647.
10.21037/qims.2018.08.03.
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Abstract
Background: To quantify the geometrical changes of each neck nodal level (NNL) and estimate the geometric planning target volume (PTV) margin during image-guided radiotherapy (IGRT) for nasopharyngeal cancer (NPC). Methods: Twenty patients with locally advanced NPC underwent one planning computed tomography (CTplan) and 6 weekly repeat CT (CTrep) scans during chemoradiotherapy. Each CTrep was rigidly registered to the CTplan. All the NNLs were manually delineated in each transverse CT section. When comparing the NNL in CTrep with CTplan, their volumes, displacement of the center of the mass, and the shortest perpendicular distance (SPD) were automatically calculated. This was followed by calculation of the systematic and random errors, overlapping index (OI), and dice similarity coefficient (DSC). With PTVs isotropically expanded from NNL by 1, 2, 3, 4, and 5 mm, they were compared with NNL itself; OI >0.95 was defined as the acceptable geometrical coverage. The Mann-Whitney test was used for statistical analysis. Results: All volumes, OI, and DSC of the NNLs (not including level IA) showed a linear decrease over time throughout the treatment course. The volume of NNLs decreased by 1–6% in the first week and 10–21% in the sixth week. The mean SPD was 1.3–1.7 and 1.9–3.5 mm in the first and sixth week respectively. The DSCs for nodal level IB, II, III, and IV were >0.7 and that of level V was <0.7 throughout the treatment course. For level IA and VI, DSC was <0.7 after the 2nd week. To maintain the OI >0.95, 2–5 mm was needed to expand the different NNLs. Conclusions: The geometrical changes of each NNL are substantial and the necessary margin of 2–5 mm depended on individual NNL is needed to maintain geometrical coverage throughout the course of IGRT for NPC.
| Type: | Article |
|---|---|
| Title: | Analysis of geometric variation of neck node levels during image-guided radiotherapy for nasopharyngeal carcinoma: recommended planning margins |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.21037/qims.2018.08.03 |
| Publisher version: | https://doi.org/10.21037/qims.2018.08.03 |
| Language: | English |
| Additional information: | This article is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License, which permits any non-commercial use, sharing, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, and provide a link to the Creative Commons license. You do not have permission under this license to share adapted material derived from this article or parts of it. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by-nc-nd/4.0/. |
| Keywords: | Head and neck cancer; radiation therapy; adaptive radiotherapy; geometrical changes |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science > Dept of Med Phys and Biomedical Eng |
| URI: | https://discovery.ucl.ac.uk/id/eprint/10100718 |
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