title: Daily CT measurement of needle applicator displacement during multifractionated high-dose-rate interstitial brachytherapy for postoperative recurrent uterine cancer.
abstract: We investigated daily needle applicator displacement during multifractionated high-dose-rate interstitial brachytherapy (HDR-ISBT) for postoperative recurrent uterine cancer. Eight patients with postoperative recurrent uterine cancer received HDR-ISBT with or without external beam radiotherapy using our unique ambulatory technique. To analyze displacement, we obtained daily computed tomography (CT) images for 122 flexible needle applicators at 21, 45, 69, and 93 hours after implantation. Displacement was defined as the length between the center of gravity of titanium markers and the needle applicator tips along the daily CT axis. For cases in which displacement was not corrected, we also calculated the dose that covered 90% of the clinical target volume (D90(CTV)) using a dose-volume histogram (DVH). Median caudal needle applicator displacement at 21, 45, 69, and 93 hours was 3, 2, 4, and 5 mm, respectively. More than 15 mm displacement was observed for 2% (2 of 122) and 17% (10 of 60) of needle applicators at 21 and 93 hours, respectively. Cases in which dwell positions were not changed to correct the treatment plan, 2 of 8 patients showed more than 10% reduction in D90(CTV) values compared with the initial treatment plan. Correction of dwell positions of the treatment source improves treatment DVH for multifractionated HDR-ISBT.
authors.affiliation: Department of Radiation Oncology, National Hospital Organization Osaka National Hospital, Osaka-city, Osaka 540-0006, Japan. kyoshida@onh.go.jp
authors.forename: Ken
authors.initials: K
authors.lastname: Yoshida
authors.forename: Mari
authors.initials: M
authors.lastname: Ueda
authors.forename: Tadashi
authors.initials: T
authors.lastname: Takenaka
authors.forename: Hideya
authors.initials: H
authors.lastname: Yamazaki
authors.forename: Tadayuki
authors.initials: T
authors.lastname: Kotsuma
authors.forename: Kazumasa
authors.initials: K
authors.lastname: Aramoto
authors.forename: Shunsuke
authors.initials: S
authors.lastname: Miyake
authors.forename: Yukihiro
authors.initials: Y
authors.lastname: Koretsune
authors.forename: Chiaki
authors.initials: C
authors.lastname: Ban
authors.forename: Eiichi
authors.initials: E
authors.lastname: Tanaka
mesh_terms: D000328:Adult; D000368:Aged; D001918:Brachytherapy / Q000295:instrumentation* / Q000379:methods; D019583:Dose Fractionation, Radiation; D005260:Female; D006801:Humans; D008875:Middle Aged; D009339:Needles; D009364:Neoplasm Recurrence, Local / Q000000981:diagnostic imaging* / Q000532:radiotherapy*; D011182:Postoperative Care / Q000379:methods; D019919:Prosthesis Implantation; D014057:Tomography, X-Ray Computed / Q000379:methods*; D016896:Treatment Outcome; D014594:Uterine Neoplasms / Q000000981:diagnostic imaging / Q000628:therapy*