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Title: Dosimetric Comparison of 3-Dimensional Planning Techniques Using an Intravaginal Multichannel Balloon Applicator for High-Dose-Rate Gynecologic Brachytherapy

Purpose: To study the dosimetric differences of various channel combinations of the Capri vaginal applicator. Methods and Materials: The Capri consists of a single central channel (R1), an inner array of 6 channels (R2), and an outer array of 6 channels (R3). Three-dimensional plans were simulated for 6 channel arrangements (R1, R2, R12, R13, R23, and R123). Treatment plans were optimized to the applicator surface or 5-mm depth while minimizing dose to organs at risk (OARs: bladder, rectum, sigmoid, and urethra). The clinical target volume (CTV) was defined as a 5-mm circumferential shell extending 4 cm in length around the applicator. Clinical target volume coverage (D{sub mean}, D{sub 90}, V{sub 100}, and V{sub 150}) and OAR doses (D{sub 0.1} {sub cm{sup 3}}, D{sub 1} {sub cm{sup 3}}, D{sub 2} {sub cm{sup 3}}, and D{sub mean}) were compared. A comparison between the Capri (R123) and a conventional single-channel applicator was also done. Statistical significance (P value <.05) was evaluated with a 2-tailed t test. Results: When prescribing to 5-mm depth, CTV coverage using all 13 channels (R123) versus a single channel (R1) was similar; however, when prescribing to the surface there were differences (P<.0001) in all CTV metrics except for themore » V{sub 150}. The R1 plans had higher doses to all OARs compared with R123 plans (P<.007). Doses to OARs were not significantly different between R23 and R123 plans (P=.05-.95), and CTV coverage differences were on the order of 1%. Capri R123 plans provided slightly lower CTV D{sub 90} and D{sub mean} but equivalent OAR doses with smaller standard deviations compared with conventional cylinder plans for both prescriptions. Conclusions: The Capri multichannel applicator provides equivalent target coverage at 5-mm depth, with significantly reduced dose to OARs relative to using a single channel. Optimal plans can be achieved using R12 (lowest V{sub 150}) or R123 or R23 (lowest OAR doses)« less
Authors:
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Publication Date:
OSTI Identifier:
22267957
Resource Type:
Journal Article
Resource Relation:
Journal Name: International Journal of Radiation Oncology, Biology and Physics; Journal Volume: 87; Journal Issue: 4; Other Information: Copyright (c) 2013 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
62 RADIOLOGY AND NUCLEAR MEDICINE; BALLOONS; BRACHYTHERAPY; CARCINOMAS; COMPARATIVE EVALUATIONS; FEMALE GENITALS; RADIATION DOSES; UROGENITAL SYSTEM DISEASES