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Dosimetric Evaluation of a High-Dose-Rate Modified-Rotte "Y" Applicator for Treatment of Inoperable Endometrial Cancer


C Esquivel

C Esquivel*, S Stathakis, T Eng, A Patel, A Gutierrez, P Mavroidis, N Papanikolaou, University of Texas HSC SA, San Antonio, TX

SU-E-T-346 Sunday 3:00PM - 6:00PM Room: Exhibit Hall

Purpose: Evaluate dosimetrically the use of a modified Rotte Y-tandem applicator for HDR brachytherapy treatment of endometrial cancer.

Methods: For inoperable endometrial cancer or patients of morbid obesity, the use of a Rotte Y-dual tandem applicator has been an integral part of treating patients with large uterine widths. Ten patient plans were selected to dosimetrically evaluate the use of a modified Rotte applicator. A third tandem was placed anteriorly and superiorly to the two lateral dual tandems inside the uterine cavity. Each patient fraction was scanned with 5 mm slice thicknesses and exported to the Oncentra v4.1 treatment planning system. A second plan was created with the use the dual-tandem applicator only. The maximum doses to the bladder, rectum, sigmoid, and intestines were found for each plan. Dose volume histograms were created to evaluate the treatments delivered. Oncentra Plan Analysis module was use to compare both plans.

Results: Using the dose volume histograms, the uterine dose coverage for one treatment was at 20% when the modified Rotte applicator was used. The plan with the unmodified, dual-tandem applicator covered 12% of uterine volume. Doses to the structures of interest were higher when the modified Rotte applicator was used, but all were still well below their dose tolerances.

Conclusion: The use of the modified Rotte applicator with a third tandem can be used to effectively cover large uterine widths for the treatment of endometrial cancer.

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