Related Experiment Video
Updated: May 6, 2026
Stereotactic Radiosurgery for Gynecologic Cancer
Published on: April 17, 2012
Dosimetric comparison of 3-dimensional planning techniques using an intravaginal multichannel balloon applicator for
Sang-June Park1, Melody Chung, D Jeffrey Demanes
1Department of Radiation Oncology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California.
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 (Dmean, D90, V100, and V150) and OAR doses (D0.1 cm3, D1 cm3, D2 cm3, and Dmean) 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 the V150. 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 D90 and Dmean 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 V150) or R123 or R23 (lowest OAR doses).
