title: Evaluation of different set-up error corrections on dose-volume metrics in prostate IMRT using CBCT images.
abstract: We investigated the effect of different set-up error corrections on dose-volume metrics in intensity-modulated radiotherapy (IMRT) for prostate cancer under different planning target volume (PTV) margin settings using cone-beam computed tomography (CBCT) images. A total of 30 consecutive patients who underwent IMRT for prostate cancer were retrospectively analysed, and 7-14 CBCT datasets were acquired per patient. Interfractional variations in dose-volume metrics were evaluated under six different set-up error corrections, including tattoo, bony anatomy, and four different target matching groups. Set-up errors were incorporated into planning the isocenter position, and dose distributions were recalculated on CBCT images. These processes were repeated under two different PTV margin settings. In the on-line bony anatomy matching groups, systematic error (∑) was 0.3 mm, 1.4 mm, and 0.3 mm in the left-right, anterior-posterior (AP), and superior-inferior directions, respectively. ∑ in three successive off-line target matchings was finally comparable with that in the on-line bony anatomy matching in the AP direction. Although doses to the rectum and bladder wall were reduced for a small PTV margin, averaged reductions in the volume receiving 100% of the prescription dose from planning were within 2.5% under all PTV margin settings for all correction groups, with the exception of the tattoo set-up error correction only (≥ 5.0%). Analysis of variance showed no significant difference between on-line bony anatomy matching and target matching. While variations between the planned and delivered doses were smallest when target matching was applied, the use of bony anatomy matching still ensured the planned doses.
authors.affiliation: Division of Radiology, Osaka Red Cross Hospital, Osaka, 534-8555, Japan.
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Hirose
authors.affiliation: Department of Radiation Oncology and Image-applied Therapy, Graduate School of Medicine, Kyoto University, 54 Kawahara-cho, Shogoin, Sakyo-ku, Kyoto, 606-8507, Japan m_nkmr@kuhp.kyoto-u.ac.jp.
authors.forename: Mitsuhiro
authors.initials: M
authors.lastname: Nakamura
authors.affiliation: Division of Radiology, Osaka Red Cross Hospital, Osaka, 534-8555, Japan.
authors.forename: Tsuneyuki
authors.initials: T
authors.lastname: Tomita
authors.affiliation: Division of Radiology, Osaka Red Cross Hospital, Osaka, 534-8555, Japan.
authors.forename: Kenji
authors.initials: K
authors.lastname: Kitsuda
authors.affiliation: Division of Radiology, Osaka Red Cross Hospital, Osaka, 534-8555, Japan.
authors.forename: Takuya
authors.initials: T
authors.lastname: Notogawa
authors.affiliation: Division of Radiology, Osaka Red Cross Hospital, Osaka, 534-8555, Japan.
authors.forename: Katsuhito
authors.initials: K
authors.lastname: Miki
authors.affiliation: Department of Radiation Oncology, Osaka Red Cross Hospital, Osaka, 534-8555, Japan.
authors.forename: Kiyonao
authors.initials: K
authors.lastname: Nakamura
authors.affiliation: Department of Radiation Oncology, Osaka Red Cross Hospital, Osaka, 534-8555, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Ishigaki
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D054893:Cone-Beam Computed Tomography / Q000379:methods*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011471:Prostatic Neoplasms / Q000000981:diagnostic imaging* / Q000532:radiotherapy*; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D061106:Radiotherapy Setup Errors / Q000517:prevention & control*; D020266:Radiotherapy, Conformal / Q000379:methods*; D061089:Radiotherapy, Image-Guided / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D016896:Treatment Outcome
keywords: dosimetry; intensity-modulated radiotherapy; prostate cancer; set-up error correction