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Title: Pattern of geometric changes of parotid gland in conventional and intensity-modulated radiotherapy in nasopharyngeal cancer patients
Authors: Zhang, Y
Liu, X
Lin, C
Lee, SWY 
Tam, SY 
Wu, VWC 
Issue Date: Sep-2018
Source: Journal of radiotherapy in practice, Sept. 2018, v. 17, no. 3, p. 274-278
Abstract: Introduction This study compared the pattern of radiation induced parotid changes between conventional (ConRT) and intensity modulated radiotherapy (IMRT) in nasopharyngeal carcinoma patients.
Methods: 56 adult NPC patients treated with IMRT (n=28) and conventional radiotherapy (n=28) were recruited. CT scans were acquired before radiotherapy, at 10th, 20th and 30th fractions, and 3 months after treatment. Parotid gland was delineated in the corresponding CT slices and its mean dose was calculated. The volumetric and geometric changes of the parotid gland at various time intervals were compared against the pre-treatment structure set. The pattern of changes was compared between the two techniques.
Results: The mean parotid dose of IMRT (37.5±9.5 Gy) was significantly lower than ConRT (49.1±7.4 Gy). The parotid gland volume, DICE similarity coefficient and lateral dimension of patient head gradually decreased during the radiotherapy course and partially recovered in 3 months post-treatment. The differences between two groups were not significant until at 3 month after treatment, where IMRT showed significantly better volume recovery.
Conclusion: Similar parotid gland size and location changes were observed during the treatment course in both ConRT and IMRT. However IMRT demonstrated better parotid volume recovery after treatment.
Keywords: Conventional radiotherapy
Intensity-modulated radiotherapy
Nasopharyngeal carcinoma
Parotid gland
Volumetric and geometric changes
Publisher: Cambridge University Press
Journal: Journal of radiotherapy in practice 
ISSN: 1460-3969
EISSN: 1467-1131
DOI: 10.1017/S1460396918000043
Rights: © Cambridge University Press 2018. This is an Open Access article, distributed under the terms of the Creative Commons Attribution licence (, which permits unrestricted re-use, distribution, and reproduction in any medium, provided the original work is properly cited.
The following publication Zhang, Y., Liu, X., Lin, C., Lee, S., Tam, S., & Wu, V. (2018). Pattern of geometric changes of parotid gland in conventional and intensity-modulated radiotherapy in nasopharyngeal cancer patients. Journal of Radiotherapy in Practice, 17(3), 274-278 is available at
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