title: Rotating-shield brachytherapy for cervical cancer.
abstract: In this treatment planning study, the potential benefits of a rotating shield brachytherapy (RSBT) technique based on a partially-shielded electronic brachytherapy source were assessed for treating cervical cancer. Conventional intracavitary brachytherapy (ICBT), intracavitary plus supplementary interstitial (IS+ICBT), and RSBT treatment plans for azimuthal emission angles of 180° (RSBT-180) and 45° (RSBT-45) were generated for five patients. For each patient, high-risk clinical target volume (HR-CTV) equivalent dose in 2 Gy fractions (EQD2) (α/β = 10 Gy) was escalated until bladder, rectum, or sigmoid colon tolerance EQD2 values were reached. External beam radiotherapy dose (1.8 Gy × 25) was accounted for, and brachytherapy was assumed to have been delivered in 5 fractions. IS+ICBT provided a greater HR-CTV D90 (minimum EQD2 to the hottest 90%) than ICBT. D90 was greater for RSBT-45 than IS+ICBT for all five patients, and greater for RSBT-180 than IS+ICBT for two patients. When the RSBT-45/180 plan with the lowest HR-CTV D90 that was greater than the D90 the ICBT or IS+ICBT plan was selected, the average (range) of D90 increases for RSBT over ICBT and IS+ICBT were 16.2 (6.3-27.2)and 8.5 (0.03-20.16) Gy, respectively. The average (range) treatment time increase per fraction of RSBT was 34.56 (3.68-70.41) min over ICBT and 34.59 (3.57-70.13) min over IS+ICBT. RSBT can increase D90 over ICBT and IS+ICBT without compromising organ-at-risk sparing. The D90 and treatment time improvements from RSBT depend on the patient and shield emission angle.
authors.affiliation: Department of Biomedical Engineering, University of Iowa, 1402 Seamans Center for the Engineering Arts and Sciences, Iowa City, IA 52242, USA.
authors.forename: Wenjun
authors.initials: W
authors.lastname: Yang
authors.forename: Yusung
authors.initials: Y
authors.lastname: Kim
authors.forename: Xiaodong
authors.initials: X
authors.lastname: Wu
authors.forename: Qi
authors.initials: Q
authors.lastname: Song
authors.forename: Yunlong
authors.initials: Y
authors.lastname: Liu
authors.forename: Sudershan K
authors.initials: SK
authors.lastname: Bhatia
authors.forename: Wenqing
authors.initials: W
authors.lastname: Sun
authors.forename: Ryan T
authors.initials: RT
authors.lastname: Flynn
mesh_terms: D001918:Brachytherapy / Q000379:methods*; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D059351:Organ Sparing Treatments; D058958:Organs at Risk / Q000528:radiation effects; D011835:Radiation Protection; D011874:Radiometry; D011880:Radiotherapy Planning, Computer-Assisted; D012399:Rotation; D002583:Uterine Cervical Neoplasms / Q000532:radiotherapy*