title: Fan-shaped complete block on helical tomotherapy for esophageal cancer: a phantom study.
abstract: Radiation pneumonitis (RP) is a common complication for radiotherapy of esophageal cancer and is associated with the low dose irradiated lung volume. This study aims to reduce the mean lung dose (MLD) and the relative lung volume at 20 Gy (V 20) and at low dose region using various designs of the fan-shaped complete block (FSCB) in helical tomotherapy. Hypothetical esophageal tumor was delineated on an anthropomorphic phantom. The FSCB was defined as the fan-shaped radiation restricted area located in both lungs. Seven treatment plans were performed with nonblock design and FSCB with different fan angles, that is, from 90° to 140°, with increment of 10°. The homogeneous index, conformation number, MLD, and the relative lung volume receiving more than 5, 10, 15, and 20 Gy (V 5, V 10, V 15, and V 20) were determined for each treatment scheme. There was a substantial reduction in the MLD, V 5, V 10, V 15, and V 20 when using different types of FSCB as compared to the nonblock design. The reduction of V 20, V 15, V 10, and V 5 was 6.3%-8.6%, 16%-23%, 42%-57%, and 42%-66% for FSCB 90°-140°, respectively. The use of FSCB in helical tomotherapy is a promising method to reduce the MLD, V 20, and relative lung volume in low dose region, especially in V 5 and V 10 for esophageal cancer.
authors.affiliation: Department of Biomedical Imaging and Radiological Sciences, National Yang Ming University, Taipei 112, Taiwan ; Division of Radiation Oncology, Department of Radiology, Far Eastern Memorial Hospital, New Taipei City 220, Taiwan.
authors.forename: Chiu-Han
authors.initials: CH
authors.lastname: Chang
authors.affiliation: Biomedical Imaging Laboratory, Department of Electrical and Computer Engineering, Faculty of Science and Technology, University of Macau, Macau.
authors.forename: Greta S P
authors.initials: GS
authors.lastname: Mok
authors.affiliation: Division of Radiation Oncology, Department of Radiology, Far Eastern Memorial Hospital, New Taipei City 220, Taiwan.
authors.forename: Pei-Wei
authors.identifier: 0000-0003-2051-364X
authors.initials: PW
authors.lastname: Shueng
authors.affiliation: Division of Radiation Oncology, Department of Radiology, Far Eastern Memorial Hospital, New Taipei City 220, Taiwan.
authors.forename: Hsin-Pei
authors.identifier: 0000-0003-3784-3709
authors.initials: HP
authors.lastname: Yeh
authors.affiliation: Department of Radiation Oncology, Koo Foundation Sun Yat-Sen Cancer Center, Taipei 112, Taiwan.
authors.forename: An-Cheng
authors.initials: AC
authors.lastname: Shiau
authors.affiliation: Division of Radiation Oncology, Department of Radiology, Far Eastern Memorial Hospital, New Taipei City 220, Taiwan.
authors.forename: Hui-Ju
authors.identifier: 0000-0002-5908-5278
authors.initials: HJ
authors.lastname: Tien
authors.affiliation: Division of Radiation Oncology, Department of Radiology, Far Eastern Memorial Hospital, New Taipei City 220, Taiwan.
authors.forename: Chi-Ta
authors.initials: CT
authors.lastname: Lin
authors.affiliation: Department of Biomedical Imaging and Radiological Sciences, National Yang Ming University, Taipei 112, Taiwan.
authors.forename: Tung-Hsin
authors.initials: TH
authors.lastname: Wu
mesh_terms: D004307:Dose-Response Relationship, Radiation; D004938:Esophageal Neoplasms / Q000532:radiotherapy*; D006801:Humans; D008168:Lung / Q000473:pathology* / Q000528:radiation effects*; D019047:Phantoms, Imaging; D017564:Radiation Pneumonitis / Q000473:pathology / Q000517:prevention & control*; D011879:Radiotherapy Dosage; D050397:Radiotherapy, Intensity-Modulated / Q000009:adverse effects* / Q000379:methods*