Abstract：
:Many head-and-neck cancer (HNC) patients treated with radiotherapy suffer significant anatomical changes due to tumor shrinkage or weight loss. The purpose of this study was to assess dose changes over target volumes and organs at risk during intensity-modulated radiotherapy for HNC patients. Sixteen HNC IMRT patients, all requiring bilateral neck irradiation, were enrolled in the study. A CTplan was performed and the initial dose distribution was calculated. During the treatment, two subsequent CTs at the 15th (CT15) and 25th (CT25) fractions were acquired. The initial plan was calculated on the CT15 and CT25, and dose-volume differences related to the CTplan were assessed. For target volumes, mean values of near-maximun absorbed dose (D2%) increased at the 25th fraction, and doses covering 95% and 98% of volume decreased significantly at the 15th fraction. Contralateral and ipsilateral parotid gland mean doses increased by 6.1% (range: -5.4, 23.5%) and 4.7% (range: -9.1, 22.3%), respectively, at CT25. The D2% in the spinal cord increased by 1.8 Gy at CT15. Mean absorbed dose increases at CT15 and CT25 were observed in: the lips, 3.8% and 5.3%; the oral cavity, 3.5% and 2.5%; and lower middle neck structure, 1.9% and 1.6%. Anatomical changes during treatment of HNC patients affect dose distribution and induce a loss of dose coverage to target volumes and an overdosage to critical structures. Appropriate organs at risk have to be contoured and monitored in order to know if the initial plan remains suitable during the course of the treatment. Reported dosimetric data can help to identify patients who could benefit from adaptive radiotherapy.
journal_name
J Appl Clin Med Physjournal_title
Journal of applied clinical medical physicsauthors
Beltran M,Ramos M,Rovira JJ,Perez-Hoyos S,Sancho M,Puertas E,Benavente S,Ginjaume M,Giralt Jdoi
10.1120/jacmp.v13i6.3723subject
Has Abstractpub_date
2012-11-08 00:00:00pages
3723issue
6issn
1526-9914journal_volume
13pub_type
杂志文章abstract：:A low-energy (50 kV) X-ray tube used for the stereotactic irradiation of intracranial lesions has been in use since 1999. The unit is calibrated prior to every procedure and during periodic quality assurance (QA) tests. The unit uses an internal and an external scintillation detector to monitor dose as well as a conve...
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journal_title：Journal of applied clinical medical physics
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journal_title：Journal of applied clinical medical physics
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journal_title：Journal of applied clinical medical physics
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journal_title：Journal of applied clinical medical physics
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journal_title：Journal of applied clinical medical physics
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更新日期：2018-01-01 00:00:00
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journal_title：Journal of applied clinical medical physics
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journal_title：Journal of applied clinical medical physics
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更新日期：2020-10-12 00:00:00
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pub_type： 杂志文章
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更新日期：2002-01-01 00:00:00
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更新日期：2007-09-24 00:00:00
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journal_title：Journal of applied clinical medical physics
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更新日期：2018-11-01 00:00:00
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更新日期：2017-09-01 00:00:00
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journal_title：Journal of applied clinical medical physics
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更新日期：2012-09-06 00:00:00
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journal_title：Journal of applied clinical medical physics
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更新日期：2018-11-01 00:00:00
