title: Estimation of the total rectal dose of radical external beam and intracavitary radiotherapy for uterine cervical cancer using the deformable image registration method.
abstract: We adapted the deformable image registration (DIR) technique to accurately calculate the cumulative intracavitary brachytherapy (ICBT) and external beam radiotherapy (EBRT) rectal dose for treating uterine cervical cancer. A total of 14 patients with primary cervical cancer radically treated with ICRT and EBRT were analysed using the Velocity AI(TM) software. Computed tomography (CT) images were registered, and EBRT and ICBT dose distributions were determined. Cumulative D2cm (3), D1cm (3) and D0.1cm (3) were calculated by simple addition of fractional values or by DIR. The accuracy of DIR was evaluated by means of a virtual phantom mimicking the rectum. The dice similarity coefficient (DSC) was calculated to evaluate rectal contour concordance between CT images before and after DIR. Virtual phantom analysis revealed that the average difference between the DIR-based phantom Dmean and the simple phantom Dmean was 1.9 ± 2.5 Gy (EQD2), and the DIR method included an uncertainty of ∼8.0%. The mean DSC between reference CT and CT was significantly improved after DIR (EBRT: 0.43 vs 0.85, P < 0.005; ICBT: 0.60 vs 0.87, P < 0.005). The average simple rectal D2cm (3), D1cm (3) and D0.1cm (3) values were 77.6, 81.6 and 91.1 Gy (EQD2), respectively; the DIR-based values were 76.2, 79.5 and 87.6 Gy, respectively. The simple addition values were overestimated, on average, by 3.1, 3.7 and 5.5 Gy, respectively, relative to the DIR-based values. In conclusion, the difference between the simple rectal dose-volume histogram (DVH) parameter addition and DIR-based cumulative rectal doses increased with decreasing DVH parameters.
authors: Department of Radiation Oncology, Osaka University Graduate School of Medicine, Osaka, Japan hayashi@radonc.med.osaka-u.ac.jp.
authors: Kazuhiko
authors: K
authors: Hayashi
authors: Department of Radiation Oncology, Osaka University Graduate School of Medicine, Osaka, Japan.
authors: Fumiaki
authors: F
authors: Isohashi
authors: Department of Radiology, Suita Tokushukai Hospital, Osaka, Japan.
authors: Yuichi
authors: Y
authors: Akino
authors: Department of Radiation Oncology, Nara Medical University, Nara, Japan.
authors: Nobuhide
authors: N
authors: Wakai
authors: Department of Obstetrics and Gynecology, Osaka University Graduate School of Medicine, Osaka, Japan.
authors: Seiji
authors: S
authors: Mabuchi
authors: Department of Radiation Oncology, Osaka University Graduate School of Medicine, Osaka, Japan.
authors: Osamu
authors: O
authors: Suzuki
authors: Department of Radiation Oncology, Osaka University Graduate School of Medicine, Osaka, Japan.
authors: Yuji
authors: Y
authors: Seo
authors: Department of Radiation Oncology, Osaka University Graduate School of Medicine, Osaka, Japan.
authors: Yuki
authors: Y
authors: Ootani
authors: Department of Radiation Oncology, Osaka University Graduate School of Medicine, Osaka, Japan.
authors: Iori
authors: I
authors: Sumida
authors: Department of Radiation Oncology, Osaka University Graduate School of Medicine, Osaka, Japan.
authors: Yasuo
authors: Y
authors: Yoshioka
authors: Department of Obstetrics and Gynecology, Osaka University Graduate School of Medicine, Osaka, Japan.
authors: Tadashi
authors: T
authors: Kimura
authors: Department of Radiation Oncology, Osaka University Graduate School of Medicine, Osaka, Japan.
authors: Kazuhiko
authors: K
authors: Ogawa
mesh_terms: D000328:Adult; D000368:Aged; D001918:Brachytherapy / Q000379:methods*; D005260:Female; D006801:Humans; D008875:Middle Aged; D058958:Organs at Risk / Q000528:radiation effects; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods; D011874:Radiometry / Q000379:methods; D011879:Radiotherapy Dosage; D020266:Radiotherapy, Conformal / Q000379:methods*; D061089:Radiotherapy, Image-Guided / Q000379:methods*; D012007:Rectum / Q000528:radiation effects*; D013382:Subtraction Technique; D014057:Tomography, X-Ray Computed / Q000379:methods; D016896:Treatment Outcome; D014594:Uterine Neoplasms / Q000000981:diagnostic imaging* / Q000532:radiotherapy*
keywords: DIR; brachytherapy; cervical cancer; rectal dose