title: Implications of free breathing motion assessed by 4D-computed tomography on the delivered dose in radiotherapy for esophageal cancer.
abstract: The aim of this study was to assess the effect of breathing motion on the delivered dose in esophageal cancer 3-dimensional (3D)-conformal radiotherapy (3D-CRT), intensity-modulated radiotherapy (IMRT), and volumetric modulated arc therapy (VMAT). We assessed 16 patients with esophageal cancer. All patients underwent 4D-computed tomography (4D-CT) for treatment planning. For each of the analyzed patients, 1 3D-CRT, 1 IMRT, and 1 VMAT (RapidArc-RA) plan were calculated. Each of the 3 initial plans was recalculated on the 4D-CT (for the maximum free inspiration and maximum free expiration) to assess the effect of breathing motion. We assessed the minimum dose (Dmin) and mean dose (Dmean) to the esophagus within the planning target volume, the volume changes of the lungs, the Dmean and the total lung volume receiving at least 40Gy (V40), and the V30, V20, V10, and V5. For the heart we assessed the Dmean and the V25. Over all techniques and all patients the change in Dmean as compared with the planned Dmean (planning CT [PCT]) to the esophagus was 0.48% in maximum free inspiration (CT_insp) and 0.55% in maximum free expiration (CT_exp). The Dmin CT_insp change was 0.86% and CT_exp change was 0.89%. The Dmean change of the lungs (heart) was in CT_insp 1.95% (2.89%) and 3.88% (2.38%) in CT_exp. In all, 4 patients had a clinically relevant change of the dose (≥ 5% Dmean to the heart and the lungs) between inspiration and expiration. These patients had a very cranially or caudally situated tumor. There are no relevant differences in the delivered dose to the regions of interest among the 3 techniques. Breathing motion management could be considered to achieve a better sparing of the lungs or heart in patients with cranially or caudally situated tumors.
authors.affiliation: Department of Radiation Oncology, Klinikum rechts der Isar, Technische Universität München, München, Germany. Electronic address: Marciana.Duma@mri.tum.de.
authors.forename: Marciana Nona
authors.initials: MN
authors.lastname: Duma
authors.affiliation: Department of Radiation Oncology, Klinikum rechts der Isar, Technische Universität München, München, Germany.
authors.forename: Johannes
authors.initials: J
authors.lastname: Berndt
authors.affiliation: Institute of Medical Statistics and Epidemiology, Klinikum rechts der Isar, Technische Universität München, München, Germany.
authors.forename: Ina-Christine
authors.initials: IC
authors.lastname: Rondak
authors.affiliation: Department of Radiation Oncology, Klinikum rechts der Isar, Technische Universität München, München, Germany.
authors.forename: Michal
authors.initials: M
authors.lastname: Devecka
authors.affiliation: Department of Radiation Oncology, Klinikum rechts der Isar, Technische Universität München, München, Germany.
authors.forename: Jan J
authors.initials: JJ
authors.lastname: Wilkens
authors.affiliation: Department of Radiation Oncology, Krankenhaus Barmherzige Schwestern Linz, Austria.
authors.forename: Hans
authors.initials: H
authors.lastname: Geinitz
authors.affiliation: Department of Radiation Oncology, Klinikum rechts der Isar, Technische Universität München, München, Germany.
authors.forename: Stephanie Elisabeth
authors.initials: SE
authors.lastname: Combs
authors.affiliation: Department of Radiation Oncology, Klinikum rechts der Isar, Technische Universität München, München, Germany.
authors.forename: Markus
authors.initials: M
authors.lastname: Oechsner
mesh_terms: D002294:Carcinoma, Squamous Cell / Q000532:radiotherapy*; D004938:Esophageal Neoplasms / Q000532:radiotherapy*; D056973:Four-Dimensional Computed Tomography; D006801:Humans; D009068:Movement; D015656:Respiratory Mechanics; D012189:Retrospective Studies
keywords: 4D-CT; Esophagus; IMRT; VMAT