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Title: A dosimetric comparison of two-phase adaptive intensity-modulated radiotherapy for locally advanced nasopharyngeal cancer
Authors: Chitapanarux I.
Chomprasert K.
Nobnaop W.
Wanwilairat S.
Tharavichitkul E.
Jakrabhandu S.
Onchan W.
Traisathit P.
Van Gestel D.
Keywords: Health, Toxicology and Mutagenesis
Radiology, Nuclear Medicine and Imaging
Issue Date: 1-Jan-2015
Publisher: Japan Radiation Research Society
Abstract: © 2015 The Author. The purpose of this investigation was to evaluate the potential dosimetric benefits of a two-phase adaptive intensity-modulated radiotherapy (IMRT) protocol for patients with locally advanced nasopharyngeal cancer (NPC). A total of 17 patients with locally advanced NPC treated with IMRT had a second computed tomography (CT) scan after 17 fractions in order to apply and continue the treatment with an adapted plan after 20 fractions. To simulate the situation without adaptation, a hybrid plan was generated by applying the optimization parameters of the original treatment plan to the anatomy of the second CT scan. The dose-volume histograms (DVHs) and dose statistics of the hybrid plan and the adapted plan were compared. The mean volume of the ipsilateral and contralateral parotid gland decreased by 6.1 cm<sup>3</sup> (30.5%) and 5.4 cm<sup>3</sup> (24.3%), respectively. Compared with the hybrid plan, the adapted plan provided a higher dose to the target volumes with better homogeneity, and a lower dose to the organs at risk (OARs). The Dmin of all planning target volumes (PTVs) increased. The Dmax of the spinal cord and brainstem were lower in 94% of the patients (1.6-5.9 Gy, P < 0.001 and 2.1-9.9 Gy, P < 0.001, respectively). The D<inf>mean</inf> of the contralateral parotid decreased in 70% of the patients (range, 0.2-4.4 Gy). We could not find a relationship between dose variability and weight loss. Our two-phase adaptive IMRT protocol improves dosimetric results in terms of target volumes and OARs in patients with locally advanced NPC.
ISSN: 04493060
Appears in Collections:SCIENCE: Journal Articles

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