open access

Vol 13, No 2 (2017)
Research paper
Published online: 2017-08-25
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Radiation-induced changes in volume and CT number of gross tumour volume and parotid glands during the course of IMRT for head and neck cancers

Mariappan Senthiappan ATHIYAMAAN, Abdul Gaffor Hasib, Chintamani Hanumantharao Sridhar, Prabhu Sudhir
DOI: 10.5603/OCP.2017.0007
·
Oncol Clin Pract 2017;13(2):39-45.

open access

Vol 13, No 2 (2017)
ORIGINAL ARTICLES
Published online: 2017-08-25

Abstract

Introduction. The CT number (CTN) for tumours and organs at risk can change with radiation therapy, which can be an early indicator for radiation response. This study investigates the correlation of radiation-induced changes in volume and CTN in gross tumour volume (GTV) and parotid glands (PG) during the course of intensity-modulated radiation therapy (IMRT) in head and neck cancers (HNC).

Materials and methods. Re-CT scans were acquired at four weeks for 71 patients with stage II IVb HNC treated with chemoradiation. The changes in volumes and CTN of the GTV primary, GTV node, and PG at four weeks of radiation were analysed. Pearson’s correlation was used to assess any association between CTN change and volume reduction of the GTVs and PGs.

Results. The volumes of the GTVs and the ipsilateral PG and contralateral PG were reduced during the course of the radiation therapy after four weeks with mean volume shrinkage of 26.30 ± 7.66 (p < 0.0001), 32.09 ± 37.2 (p < 0.04), 8.38 ± 1.61 (p < 0.0001), and 9.10 ± 1.81 cm3 (p < 0.0001), respectively, and the mean CTN reduced by 2.50 ± 5.4, 1.79 ± 4.12, 1.90 ± 3.57, and 1.99 ± 3.54 HUs, respectively. For GTVs, the CTN and GTV volume decreases were found to be positively correlated, but the relationship was weak. However, no noticeable correlation was observed between the CTN change and the volume change in both PGs.

Conclusions. The CTN changes in GTVs and PGs during delivery of radiation for HNC are measurable and patient specific. The CTN can be reduced in GTVs and PGs with a reasonable correlation between the mean CTN and volume reductions in GTVs, but with no correlation with PGs.

Abstract

Introduction. The CT number (CTN) for tumours and organs at risk can change with radiation therapy, which can be an early indicator for radiation response. This study investigates the correlation of radiation-induced changes in volume and CTN in gross tumour volume (GTV) and parotid glands (PG) during the course of intensity-modulated radiation therapy (IMRT) in head and neck cancers (HNC).

Materials and methods. Re-CT scans were acquired at four weeks for 71 patients with stage II IVb HNC treated with chemoradiation. The changes in volumes and CTN of the GTV primary, GTV node, and PG at four weeks of radiation were analysed. Pearson’s correlation was used to assess any association between CTN change and volume reduction of the GTVs and PGs.

Results. The volumes of the GTVs and the ipsilateral PG and contralateral PG were reduced during the course of the radiation therapy after four weeks with mean volume shrinkage of 26.30 ± 7.66 (p < 0.0001), 32.09 ± 37.2 (p < 0.04), 8.38 ± 1.61 (p < 0.0001), and 9.10 ± 1.81 cm3 (p < 0.0001), respectively, and the mean CTN reduced by 2.50 ± 5.4, 1.79 ± 4.12, 1.90 ± 3.57, and 1.99 ± 3.54 HUs, respectively. For GTVs, the CTN and GTV volume decreases were found to be positively correlated, but the relationship was weak. However, no noticeable correlation was observed between the CTN change and the volume change in both PGs.

Conclusions. The CTN changes in GTVs and PGs during delivery of radiation for HNC are measurable and patient specific. The CTN can be reduced in GTVs and PGs with a reasonable correlation between the mean CTN and volume reductions in GTVs, but with no correlation with PGs.

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Keywords

head and neck cancer, CT number change, IMRT, gross tumour volume, parotid glands

About this article
Title

Radiation-induced changes in volume and CT number of gross tumour volume and parotid glands during the course of IMRT for head and neck cancers

Journal

Oncology in Clinical Practice

Issue

Vol 13, No 2 (2017)

Article type

Research paper

Pages

39-45

Published online

2017-08-25

DOI

10.5603/OCP.2017.0007

Bibliographic record

Oncol Clin Pract 2017;13(2):39-45.

Keywords

head and neck cancer
CT number change
IMRT
gross tumour volume
parotid glands

Authors

Mariappan Senthiappan ATHIYAMAAN
Abdul Gaffor Hasib
Chintamani Hanumantharao Sridhar
Prabhu Sudhir

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