title: The usefulness of an independent patient-specific treatment planning verification method using a benchmark plan in high-dose-rate intracavitary brachytherapy for carcinoma of the uterine cervix.
abstract: To develop an easy independent patient-specific quality assurance (QA) method using a benchmark plan for high-dose-rate intracavitary brachytherapy for cervix cancer, we conducted benchmark treatment planning with various sizes and combinations of tandem-ovoid and tandem-cylinder applications with 'ideal' geometry outside the patient. Two-dimensional-based treatment planning was conducted based on the Manchester method. We predicted the total dwell time of individual treatment plans from the air kerma strength, total dwell time and prescription dose of the benchmark plan. In addition, we recorded the height (dh), width (dw) and thickness (dt) covered with 100% isodose line. These parameters were compared with 169 and 29 clinical cases for tandem-ovoid or tandem-cylinder cases, respectively. With regard to tandem-ovoid cases, differences in total dwell time, dh, dt and dw between benchmark and individual plans were on average -0.2% ± 3.8%, -1.0 mm ± 2.6 mm, 0.8 mm ± 1.3 mm and -0.1 mm ± 1.5 mm, respectively. With regard to tandem-cylinder cases, differences in total dwell time, dh(front) (the distance from tandem tip to tandem ring), dt and dw between benchmark and individual plans were on average -1.5% ± 3.1%, -1.5 mm ± 4.9 mm, 0.1 mm ± 1.0 mm and 0.2 mm ± 0.8 mm, respectively. Of two cases, more than 13% differences in total dwell time were observed between benchmark plans and the clinical cases, which turned out to be due to the use of the wrong source position setting. These results suggest that our method is easy and useful for independent verification of patient-specific treatment planning QA.
authors: Department of Radiation Oncology, Osaka University Graduate School of Medicine, 2-2 Yamada-oka, Suita, Osaka, Japan. ytakahashi@radonc.med.osaka-u.ac.jp
authors: Yutaka
authors: Y
authors: Takahashi
authors: Masahiko
authors: M
authors: Koizumi
authors: Iori
authors: I
authors: Sumida
authors: Fumiaki
authors: F
authors: Isohashi
authors: Toshiyuki
authors: T
authors: Ogata
authors: Yuichi
authors: Y
authors: Akino
authors: Yasuo
authors: Y
authors: Yoshioka
authors: Shintaro
authors: S
authors: Maruoka
authors: Shinichi
authors: S
authors: Inoue
authors: Koji
authors: K
authors: Konishi
authors: Kazuhiko
authors: K
authors: Ogawa
mesh_terms: D019985:Benchmarking; D001918:Brachytherapy / Q000592:standards*; D005260:Female; D006801:Humans; D007564:Japan; D011785:Quality Assurance, Health Care / Q000379:methods*; D011874:Radiometry / Q000592:standards*; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000592:standards*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014594:Uterine Neoplasms / Q000532:radiotherapy*