title: [Impact of multileaf collimator leaf positioning accuracy on intensity modulated radiation therapy].
abstract: In multileaf collimator (MLC)-based intensity modulated radiation therapy (IMRT), the dose is influenced by the uncertainty of MLC driving control. In this study, we examined the influence of MLC driving control accuracy on dose evaluation (gamma analysis) by evaluating 60-day MLC driving control accuracy (stationary positioning accuracy and positioning reproducibility) once a week as well as measuring IMRT dose distribution. The MLC positioning accuracy accompanied variation over time and tended to expand by 0.1 to 0.15 mm in one week and about 1 mm in 60 days. In terms of reproducibility, errors were within 0.2 mm for more than 95%. For prostate IMRT, when MLC stationary positioning accuracy was around 1 mm, no significant difference was observed in the pass rate in gamma analysis. Therefore, the results suggest that regular maintenance by setting a permissible value determined by the MLC positioning accuracy test can be an effective indicator in the future for maintaining the safety of IMRT.
authors.affiliation: Department of Radiology, Tokushima University Hospital.
authors.forename: Motoharu
authors.initials: M
authors.lastname: Sasaki
authors.forename: Masahide
authors.initials: M
authors.lastname: Tominaga
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Ikushima
authors.forename: Taro
authors.initials: T
authors.lastname: Kishi
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Kawashita
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Hara
authors.forename: Yukiko
authors.initials: Y
authors.lastname: Fukunaga
authors.forename: Masashi
authors.initials: M
authors.lastname: Kimura
authors.forename: Yasufumi
authors.initials: Y
authors.lastname: Shitakubo
authors.forename: Satoru
authors.initials: S
authors.lastname: Takashi
authors.forename: Masataka
authors.initials: M
authors.lastname: Oita
mesh_terms: D002138:Calibration; D006801:Humans; D008297:Male; D056888:Patient Positioning; D011879:Radiotherapy Dosage; D050397:Radiotherapy, Intensity-Modulated / Q000379:methods* / Q000592:standards; D015203:Reproducibility of Results