title: Dose impact of rectal gas on prostatic IMRT and VMAT.
abstract: OBJECTIVE
  In this study, we compared the dose impact of the heterogeneity caused by rectal gas using two methods of treatment planning for intensity-modulated radiotherapy (IMRT) and volumetric-modulated arc therapy (VMAT).
  
  
  METHODS
  In addition to the structure set used for the standard treatment plan, we created a structure set for evaluation for each patient. These sets were transferred to the same isocenter as the respective treatment plans for IMRT and VMAT that were to become the standard. Values were then recalculated.
  
  
  RESULTS
  During the standard prostatic IMRT and VMAT treatment planning, all study participants met dose restrictions in place at our hospital. Dose restrictions were fulfilled in treatment plans for evaluation, excluding those with a clinical target volume (CTV) of V(100%) and planning target volume (PTV) of D95 when the rectum was excluded. However, in treatment plans for evaluation, IMRT was shown to have a higher concordance rate with standard treatment plans than VMAT.
  
  
  CONCLUSIONS
  If rectal gas is present during either IMRT or VMAT, a dose decrease will occur in relation to CTV and PTV, suggesting that a plan does not eliminate adverse effects on organs at risk.
authors.affiliation: Department of Radiological Technology, Tokushima University Hospital, 2-50-1 Kuramoto-cho, Tokushima, Tokushima, 770-8503, Japan. msasaki@tokushima-u.ac.jp.|Department of Radiology and Radiation Oncology, Institute of Biomedical Sciences, Tokushima University Graduate School, 3-18-15 Kuramoto-cho, Tokushima, Tokushima, 770-8503, Japan. msasaki@tokushima-u.ac.jp.
authors.forename: Motoharu
authors.initials: M
authors.lastname: Sasaki
authors.affiliation: Department of Therapeutic Radiology, Institute of Biomedical Sciences, Tokushima University Graduate School, 3-18-15 Kuramoto-cho, Tokushima, Tokushima, 770-8503, Japan.
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Ikushima
authors.affiliation: Department of Therapeutic Radiology, Institute of Biomedical Sciences, Tokushima University Graduate School, 3-18-15 Kuramoto-cho, Tokushima, Tokushima, 770-8503, Japan.
authors.forename: Masahide
authors.initials: M
authors.lastname: Tominaga
authors.affiliation: Department of Therapeutic Radiology, Nagoya University Graduate School of Medicine, 65 Tsurumai, Showa-ku, Nagoya, Aichi, 466-8550, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Kamomae
authors.affiliation: Department of Radiological Technology, Tokushima University Hospital, 2-50-1 Kuramoto-cho, Tokushima, Tokushima, 770-8503, Japan.
authors.forename: Taro
authors.initials: T
authors.lastname: Kishi
authors.affiliation: Graduate School of Health Science, University of Okayama, 2-5-1 Shikata-cho, Okayama Kita-ku, Okayama, 700-8558, Japan.
authors.forename: Masataka
authors.initials: M
authors.lastname: Oita
authors.affiliation: Department of Radiology and Radiation Oncology, Institute of Biomedical Sciences, Tokushima University Graduate School, 3-18-15 Kuramoto-cho, Tokushima, Tokushima, 770-8503, Japan.
authors.forename: Masafumi
authors.initials: M
authors.lastname: Harada
mesh_terms: D005414:Flatulence / Q000503:physiopathology*; D006801:Humans; D021621:Imaging, Three-Dimensional; D008297:Male; D011467:Prostate / Q000000981:diagnostic imaging; D011471:Prostatic Neoplasms / Q000503:physiopathology / Q000532:radiotherapy*; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D050397:Radiotherapy, Intensity-Modulated / Q000379:methods*; D012007:Rectum / Q000000981:diagnostic imaging / Q000503:physiopathology*; D014057:Tomography, X-Ray Computed
keywords: Dose distribution; Gas; Intensity-modulated radiotherapy; Prostate cancer; Volumetric-modulated arc therapy