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A Planning Study Comparison of the Single Tandem and Rotterdam Y Applicators in HDR Brachytherapy for Inoperable Endometrial Cancer

A Lau1*, C Rivers2 , D Mattson1,2 , H Malhotra1,2 , (1)State University of New York at Buffalo ,Buffalo, NY, (2)Roswell Park Comprehensive Cancer Center, Buffalo, NY


(Sunday, 7/29/2018) 3:00 PM - 6:00 PM

Room: Exhibit Hall

Purpose: HDR brachytherapy has demonstrated the capability to achieve excellent results in selected inoperable endometrial cancer (IEC) patients due to the ability to select dwell times and positions. Two types of applicators that are used to treat IEC are the single tandem and the Rotterdam "Y" applicator. The purpose of this study is to dosimetrically compare both applicators in delivering equivalent plans while using two different plan optimization methods.

Methods: Eleven patients that were treated with either the single or “Y� tandem applicator were included in this study. Each treatment consisted of two separately planned fractions. For each fraction, additional plans were created in the Oncentra® Brachy treatment planning system (TPS): the original plan using target optimization, an identical plan simulating the other applicator using point optimization with the Madison points system and the simulated applicator using target optimization. Patients were grouped by their original applicator type. The uterus D100, D90, V100 and V150, bladder D0.1cc, D1cc and D2cc and rectum D0.1cc, D1cc and D2cc were recorded from the TPS for all plans.

Results: For patients in the “Y� tandem group, using a simulated single tandem reduced the target coverage >10% for 9/11 plans while also increasing dose to the bladder. For patients in the single tandem group, using a simulated “Y� tandem resulted in target coverage within 5% of the original clinical plan in 5/10 plans. Target optimization resulted in either similar or increased target coverage in 16/22 plans in the “Y� tandem group and 11/20 plans in the single tandem group.

Conclusion: For selected patients, results have demonstrated that a “Y� tandem applicator provides better or comparable target coverage with the trade-off of increasing the dose to normal tissue. Patient specific anatomy also influences the choice of applicator that is chosen for treatment.


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