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Rules of parotid gland dose variations and shift during intensity modulated radiation therapy for nasopharyngeal carcinoma
BACKGROUND: To determine the position and dose delivery changes rules of parotid gland (PG) during the course of intensity modulated radiation therapy (IMRT) in nasopharyngeal carcinoma patients (NPC). MATERIALS AND METHODS: One hundred and forty one competed tomography (CT) images from 47 NPC patie...
Autores principales: | , , , , , , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
BioMed Central
2015
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4298965/ https://www.ncbi.nlm.nih.gov/pubmed/25566789 http://dx.doi.org/10.1186/s13014-014-0307-2 |
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author | Wang, Wei Yang, Haihua Mi, Yucheng Hu, Wei Ding, Weijun Xie, Youyou Cai, Yujie Chen, Xiaofeng |
author_facet | Wang, Wei Yang, Haihua Mi, Yucheng Hu, Wei Ding, Weijun Xie, Youyou Cai, Yujie Chen, Xiaofeng |
author_sort | Wang, Wei |
collection | PubMed |
description | BACKGROUND: To determine the position and dose delivery changes rules of parotid gland (PG) during the course of intensity modulated radiation therapy (IMRT) in nasopharyngeal carcinoma patients (NPC). MATERIALS AND METHODS: One hundred and forty one competed tomography (CT) images from 47 NPC patients (three images for each patient were acquired before treatment, at the 15th and 25th fraction during the treatment) who underwent radical IMRT were selected for this study. A total of 70-76Gy at 2.12–2.3 Gy/fraction/d was given to the GTVnx in 33 fractions. The distances between the lateral/medial aspects of PG and midline (DLM and DMM) at the level of odontoid process were measured. The dose differences between plan and actual delivery were calculated. RESULTS: The volume reductions of PGs between fractions 15 and 25 were larger than those in the first 15 fractions (4.68 ± 3.23 cc vs. 2.46 ± 4.55 cc for the right PG and 5.96 ± 2.99 cc vs. 2.06 ± 2.99 cc for the left PG). However, the percentage of gland volume receiving ≥30 Gy (V30) of bilateral PGs decreased more significantly in the first 15 fractions than that between fractions 15 and 25 (5.61 ± 16.04% vs. 1.14 ± 21.54% for the right PG and 6.87 ± 15.58% vs. 0.81 ± 15.94% for the left PG). The gross tumor volume of the nasopharynx (GTVnx) decreased more significantly in the first 15 fractions than that between the 15th and 25th fraction (8.23 ± 13.61 cc vs. 3.30 ± 8.09 cc). The DMM of ipsilateral PGs reduced in the first 15 fractions (0.80 ± 2.96 mm) but increased between fraction 15 and 25 (−2.19 ± 3.96 mm). While ipsilateral PG shifted into target volume but shifted out target volume between fraction 15 and 25. Parotid glands V30 was correlated with GTVnx, GTVnx reduction and DMM reduction (p < 0.01). CONCLUSION: Our results indicate that the reduction of GTVnx leads to the positional change of the parotid gland, which results in more significant dose change of the parotid gland in the first 15 fractions than that between fraction 15 and 25. |
format | Online Article Text |
id | pubmed-4298965 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2015 |
publisher | BioMed Central |
record_format | MEDLINE/PubMed |
spelling | pubmed-42989652015-01-21 Rules of parotid gland dose variations and shift during intensity modulated radiation therapy for nasopharyngeal carcinoma Wang, Wei Yang, Haihua Mi, Yucheng Hu, Wei Ding, Weijun Xie, Youyou Cai, Yujie Chen, Xiaofeng Radiat Oncol Research BACKGROUND: To determine the position and dose delivery changes rules of parotid gland (PG) during the course of intensity modulated radiation therapy (IMRT) in nasopharyngeal carcinoma patients (NPC). MATERIALS AND METHODS: One hundred and forty one competed tomography (CT) images from 47 NPC patients (three images for each patient were acquired before treatment, at the 15th and 25th fraction during the treatment) who underwent radical IMRT were selected for this study. A total of 70-76Gy at 2.12–2.3 Gy/fraction/d was given to the GTVnx in 33 fractions. The distances between the lateral/medial aspects of PG and midline (DLM and DMM) at the level of odontoid process were measured. The dose differences between plan and actual delivery were calculated. RESULTS: The volume reductions of PGs between fractions 15 and 25 were larger than those in the first 15 fractions (4.68 ± 3.23 cc vs. 2.46 ± 4.55 cc for the right PG and 5.96 ± 2.99 cc vs. 2.06 ± 2.99 cc for the left PG). However, the percentage of gland volume receiving ≥30 Gy (V30) of bilateral PGs decreased more significantly in the first 15 fractions than that between fractions 15 and 25 (5.61 ± 16.04% vs. 1.14 ± 21.54% for the right PG and 6.87 ± 15.58% vs. 0.81 ± 15.94% for the left PG). The gross tumor volume of the nasopharynx (GTVnx) decreased more significantly in the first 15 fractions than that between the 15th and 25th fraction (8.23 ± 13.61 cc vs. 3.30 ± 8.09 cc). The DMM of ipsilateral PGs reduced in the first 15 fractions (0.80 ± 2.96 mm) but increased between fraction 15 and 25 (−2.19 ± 3.96 mm). While ipsilateral PG shifted into target volume but shifted out target volume between fraction 15 and 25. Parotid glands V30 was correlated with GTVnx, GTVnx reduction and DMM reduction (p < 0.01). CONCLUSION: Our results indicate that the reduction of GTVnx leads to the positional change of the parotid gland, which results in more significant dose change of the parotid gland in the first 15 fractions than that between fraction 15 and 25. BioMed Central 2015-01-08 /pmc/articles/PMC4298965/ /pubmed/25566789 http://dx.doi.org/10.1186/s13014-014-0307-2 Text en © Wang et al.; licensee BioMed Central. 2015 This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly credited. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated. |
spellingShingle | Research Wang, Wei Yang, Haihua Mi, Yucheng Hu, Wei Ding, Weijun Xie, Youyou Cai, Yujie Chen, Xiaofeng Rules of parotid gland dose variations and shift during intensity modulated radiation therapy for nasopharyngeal carcinoma |
title | Rules of parotid gland dose variations and shift during intensity modulated radiation therapy for nasopharyngeal carcinoma |
title_full | Rules of parotid gland dose variations and shift during intensity modulated radiation therapy for nasopharyngeal carcinoma |
title_fullStr | Rules of parotid gland dose variations and shift during intensity modulated radiation therapy for nasopharyngeal carcinoma |
title_full_unstemmed | Rules of parotid gland dose variations and shift during intensity modulated radiation therapy for nasopharyngeal carcinoma |
title_short | Rules of parotid gland dose variations and shift during intensity modulated radiation therapy for nasopharyngeal carcinoma |
title_sort | rules of parotid gland dose variations and shift during intensity modulated radiation therapy for nasopharyngeal carcinoma |
topic | Research |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4298965/ https://www.ncbi.nlm.nih.gov/pubmed/25566789 http://dx.doi.org/10.1186/s13014-014-0307-2 |
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