title: Availability of applying diaphragm matching with the breath-holding technique in stereotactic body radiation therapy for liver tumors.
abstract: OBJECTIVE
  Image-guided radiotherapy (IGRT) based on bone matching can produce large target-positioning errors because of expiration breath-hold reproducibility during stereotactic body radiation therapy (SBRT) for liver tumors. Therefore, the feasibility of diaphragm-based 3D image matching between planning computed tomography (CT) and pretreatment cone-beam CT was investigated.
  
  
  METHODS
  In 59 liver SBRT cases, Lipiodol uptake after transarterial chemoembolization was defined as a tumor marker. Further, the relative isocenter coordinate that was obtained by Lipiodol matching was defined as the reference coordinate. The distance between the relative isocenter coordinate and reference coordinate, which was obtained from diaphragm matching and bone matching techniques, was defined as the target positioning error. Furthermore, the target positioning error between liver matching and Lipiodol matching was evaluated.
  
  
  RESULTS
  The positioning errors in all directions by the diaphragm matching were significantly smaller than those obtained by using by the bone matching technique (p < 0.05). Further, the positioning errors in the A-P and C-C directions that were obtained by using liver matching were significantly smaller than those obtained by using bone matching (p < 0.05). The estimated PTV margins calculated by the formula proposed by van Herk for diaphragm matching, liver matching, and bone matching were 5.0 mm, 5.0 mm, and 11.6 mm in the C-C direction; 3.6 mm, 2.4 mm, and 6.9 mm in the A-P direction; and 2.6 mm, 4.1 mm, and 4.6 mm in the L-R direction, respectively.
  
  
  CONCLUSIONS
  Diaphragm matching-based IGRT may be an alternative image matching technique for determining liver tumor positions in patients.
authors.affiliation: Section of Radiation Therapy, Department of Clinical Support, Hiroshima University Hospital, 1-2-3, Kasumi, Minami-ku, Hiroshima City 734-8551, Japan; Course of Medical and Dental Sciences, Graduate School of Biomedical & Health Sciences, Hiroshima University, 1-2-3, Kasumi, Minami-ku, Hiroshima City 734-8551, Japan. Electronic address: daika99@hiroshima-u.ac.jp.
authors.forename: Daisuke
authors.initials: D
authors.lastname: Kawahara
authors.affiliation: Department of Radiation Oncology, Institute of Biomedical & Health Sciences, Hiroshima University, 1-2-3, Kasumi, Minami-ku, Hiroshima City 734-8551, Japan.
authors.forename: Shuichi
authors.initials: S
authors.lastname: Ozawa
authors.affiliation: Department of Radiation Oncology, Institute of Biomedical & Health Sciences, Hiroshima University, 1-2-3, Kasumi, Minami-ku, Hiroshima City 734-8551, Japan.
authors.forename: Tomoki
authors.initials: T
authors.lastname: Kimura
authors.affiliation: Department of Radiation Oncology, Institute of Biomedical & Health Sciences, Hiroshima University, 1-2-3, Kasumi, Minami-ku, Hiroshima City 734-8551, Japan.
authors.forename: Takeo
authors.initials: T
authors.lastname: Nakashima
authors.affiliation: Section of Radiation Therapy, Department of Clinical Support, Hiroshima University Hospital, 1-2-3, Kasumi, Minami-ku, Hiroshima City 734-8551, Japan.
authors.forename: Masamichi
authors.initials: M
authors.lastname: Aita
authors.affiliation: Section of Radiation Therapy, Department of Clinical Support, Hiroshima University Hospital, 1-2-3, Kasumi, Minami-ku, Hiroshima City 734-8551, Japan.
authors.forename: Shintaro
authors.initials: S
authors.lastname: Tsuda
authors.affiliation: Section of Radiation Therapy, Department of Clinical Support, Hiroshima University Hospital, 1-2-3, Kasumi, Minami-ku, Hiroshima City 734-8551, Japan.
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Ochi
authors.affiliation: Section of Radiation Therapy, Department of Clinical Support, Hiroshima University Hospital, 1-2-3, Kasumi, Minami-ku, Hiroshima City 734-8551, Japan.
authors.forename: Takuro
authors.initials: T
authors.lastname: Okumura
authors.affiliation: Section of Radiation Therapy, Department of Clinical Support, Hiroshima University Hospital, 1-2-3, Kasumi, Minami-ku, Hiroshima City 734-8551, Japan.
authors.forename: Hirokazu
authors.initials: H
authors.lastname: Masuda
authors.affiliation: Section of Radiation Therapy, Department of Clinical Support, Hiroshima University Hospital, 1-2-3, Kasumi, Minami-ku, Hiroshima City 734-8551, Japan.
authors.forename: Yoshimi
authors.initials: Y
authors.lastname: Ohno
authors.affiliation: Department of Radiation Oncology, Institute of Biomedical & Health Sciences, Hiroshima University, 1-2-3, Kasumi, Minami-ku, Hiroshima City 734-8551, Japan.
authors.forename: Yuji
authors.initials: Y
authors.lastname: Murakami
authors.affiliation: Department of Radiation Oncology, Institute of Biomedical & Health Sciences, Hiroshima University, 1-2-3, Kasumi, Minami-ku, Hiroshima City 734-8551, Japan.
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Nagata
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D006528:Carcinoma, Hepatocellular / Q000000981:diagnostic imaging / Q000378:metabolism / Q000532:radiotherapy*; D016461:Chemoembolization, Therapeutic / Q000379:methods; D003287:Contrast Media / Q000008:administration & dosage / Q000493:pharmacokinetics; D003964:Diaphragm / Q000033:anatomy & histology / Q000000981:diagnostic imaging / Q000502:physiology*; D004998:Ethiodized Oil / Q000008:administration & dosage / Q000493:pharmacokinetics; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods; D008113:Liver Neoplasms / Q000000981:diagnostic imaging / Q000378:metabolism / Q000532:radiotherapy*; D008875:Middle Aged; D016634:Radiosurgery / Q000379:methods*; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D015656:Respiratory Mechanics / Q000502:physiology
chemical_list: D003287:Contrast Media; D004998:Ethiodized Oil
keywords: Cone-beam computed tomography; Diaphragm matching; Stereotactic body radiotherapy