Relative plan robustness of step-and-shoot vs rotational intensity-modulated radiotherapy on repeat computed tomographic simulation for weight loss in head and neck cancer.

Autor:	Thomson DJ; Department of Clinical Oncology, The Christie NHS Foundation Trust, Manchester, UK; The University of Manchester, Manchester Academic Health Science Centre, Institute of Cancer Sciences, Manchester, UK., Beasley WJ; The University of Manchester, Manchester Academic Health Science Centre, Institute of Cancer Sciences, Manchester, UK; Christie Medical Physics and Engineering, The Christie NHS Foundation Trust, Manchester, UK., Garcez K; Department of Clinical Oncology, The Christie NHS Foundation Trust, Manchester, UK., Lee LW; Department of Clinical Oncology, The Christie NHS Foundation Trust, Manchester, UK., Sykes AJ; Department of Clinical Oncology, The Christie NHS Foundation Trust, Manchester, UK., Rowbottom CG; The University of Manchester, Manchester Academic Health Science Centre, Institute of Cancer Sciences, Manchester, UK; Christie Medical Physics and Engineering, The Christie NHS Foundation Trust, Manchester, UK., Slevin NJ; Department of Clinical Oncology, The Christie NHS Foundation Trust, Manchester, UK; The University of Manchester, Manchester Academic Health Science Centre, Institute of Cancer Sciences, Manchester, UK. Electronic address: nick.slevin@christie.nhs.uk.
Jazyk:	angličtina
Zdroj:	Medical dosimetry : official journal of the American Association of Medical Dosimetrists [Med Dosim] 2016 Summer; Vol. 41 (2), pp. 154-8. Date of Electronic Publication: 2016 Mar 15.
DOI:	10.1016/j.meddos.2016.01.001
Abstrakt:	Introduction: Interfractional anatomical alterations may have a differential effect on the dose delivered by step-and-shoot intensity-modulated radiotherapy (IMRT) and volumetric-modulated arc therapy (VMAT). The increased degrees of freedom afforded by rotational delivery may increase plan robustness (measured by change in target volume coverage and doses to organs at risk [OARs]). However, this has not been evaluated for head and neck cancer. Materials and Methods: A total of 10 patients who required repeat computed tomography (CT) simulation and replanning during head and neck IMRT were included. Step-and-shoot IMRT and VMAT plans were generated from the original planning scan. The initial and second CT simulation scans were fused and targets/OAR contours transferred, reviewed, and modified. The plans were applied to the second CT scan and doses recalculated without repeat optimization. Differences between step-and-shoot IMRT and VMAT for change in target volume coverage and doses to OARs between first and second CT scans were compared by Wilcoxon signed rank test. Results: There were clinically relevant dosimetric changes between the first and the second CT scans for both the techniques (reduction in mean D95% for PTV2 and PTV3, Dmin for CTV2 and CTV3, and increased mean doses to the parotid glands). However, there were no significant differences between step-and-shoot IMRT and VMAT for change in any target coverage parameter (including D95% for PTV2 and PTV3 and Dmin for CTV2 and CTV3) or dose to any OARs (including parotid glands) between the first and the second CT scans. Conclusions: For patients with head and neck cancer who required replanning mainly due to weight loss, there were no significant differences in plan robustness between step-and-shoot IMRT and VMAT. This information is useful with increased clinical adoption of VMAT. (Copyright © 2016 American Association of Medical Dosimetrists. Published by Elsevier Inc. All rights reserved.)
Databáze:	MEDLINE
Externí odkaz:	Zobrazit plný text záznamu