title: Inverse planning for combination of intracavitary and interstitial brachytherapy for locally advanced cervical cancer.
abstract: The main purpose of this study was to compare three different treatment plans for locally advanced cervical cancer: (i) the inverse-planning simulated annealing (IPSA) plan for combination brachytherapy (BT) of interstitial and intracavitary brachytherapy, (ii) manual optimization based on the Manchester system for combination-BT, and (iii) the conventional Manchester system using only tandem and ovoids. This was a retrospective study of 25 consecutive implants. The high-risk clinical target volume (HR-CTV) and organs at risk were defined according to the GEC-ESTRO Working Group definitions. A dose of 6 Gy was prescribed. The uniform cost function for dose constraints was applied to all IPSA-generated plans. The coverage of the HR-CTV by IPSA for combination-BT was equivalent to that of manual optimization, and was better than that of the Manchester system using only tandem and ovoids. The mean V100 achieved by IPSA for combination-BT, manual optimization and Manchester was 96 ± 3.7%, 95 ± 5.5% and 80 ± 13.4%, respectively. The mean D100 was 483 ± 80, 487 ± 97 and 335 ± 119 cGy, respectively. The mean D90 was 677 ± 61, 681 ± 88 and 513 ± 150 cGy, respectively. IPSA resulted in significant reductions of the doses to the rectum (IPSA D2cm(3): 408 ± 71 cGy vs manual optimization D2cm(3): 485 ± 105 cGy; P = 0.03) and the bladder (IPSA D2cm(3): 452 ± 60 cGy vs manual optimization D2cm(3): 583 ± 113 cGy; P < 0.0001). In conclusion, combination-BT achieved better tumor coverage, and plans using IPSA provided significant sparing of normal tissues without compromising CTV coverage.
authors.affiliation: Department of Radiation Oncology, National Cancer Center Hospital, Tokyo, Japan.
authors.forename: Kotaro
authors.initials: K
authors.lastname: Yoshio
authors.forename: Naoya
authors.initials: N
authors.lastname: Murakami
authors.forename: Madoka
authors.initials: M
authors.lastname: Morota
authors.forename: Ken
authors.initials: K
authors.lastname: Harada
authors.forename: Mayuka
authors.initials: M
authors.lastname: Kitaguchi
authors.forename: Kentaro
authors.initials: K
authors.lastname: Yamagishi
authors.forename: Shuhei
authors.initials: S
authors.lastname: Sekii
authors.forename: Kana
authors.initials: K
authors.lastname: Takahashi
authors.forename: Koji
authors.initials: K
authors.lastname: Inaba
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Mayahara
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Ito
authors.forename: Minako
authors.initials: M
authors.lastname: Sumi
authors.forename: Susumu
authors.initials: S
authors.lastname: Kanazawa
authors.forename: Jun
authors.initials: J
authors.lastname: Itami
mesh_terms: D000328:Adult; D001918:Brachytherapy / Q000379:methods*; D003131:Combined Modality Therapy / Q000379:methods; D005260:Female; D006801:Humans; D008875:Middle Aged; D011874:Radiometry / Q000379:methods*; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D016896:Treatment Outcome; D002583:Uterine Cervical Neoplasms / Q000532:radiotherapy*
keywords: HDR; IPSA; cervical cancer; combination brachytherapy; optimize