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A Comprehensive Planning Comparison Study Between a Novel Direction Modulated Brachytherapy Tandem Applicator and Conventional T&R Applicator for Image Guided Cervical Cancer Brachytherapy

D Han

D Han1*, K Tanderup2 , H Safigholi3 , A Soliman3 , D Scanderbeg1,4 , Z Liu1 , W Song3 , (1) University of California, San Diego, La Jolla, California, (2) Aarhus University, Denmark, (3) Sunnybrook Research Institute, Sunnybrook Health Sciences Centre, Toronto, Ontario, (4) UCSD Medical Center, La Jolla, CA, (6) University of California, San Diego, La Jolla, California


TU-AB-201-1 (Tuesday, July 14, 2015) 7:30 AM - 9:30 AM Room: 201

To demonstrate that utilization of a novel, intensity modulation capable, direction modulated brachytherapy (DMBT) tandem applicator can improve plan quality compared with conventional T&R applicator during an image guided cervical cancer brachytherapy.

Materials and Methods:
45 cervical cancer patients treated with PDR brachytherapy were reviewed. Of them, a) 27 were treated using T&R only, b) 9 were treated using T&R with needles attached to the ring, and c) the remaining 9 were treated using T&R with needles attached to the ring (AN) as well as additional free-hand-loaded needles (FN). The DMBT tandem design has 6 peripheral holes of 1.3-mm diameter, grooved along a nonmagnetic tungsten alloy rod, enclosed in a plastic sheath with total 6.0-mm diameter. An in-house-coded inverse planning system was used for planning DMBT and T&R cases. All typical clinical constraints including OAR dose limits, dwell times, and loading patterns were respected. For the DMBT and T&R applicators, the plans were optimized with the same conventional ring in place, but repeatedly planned with and without AN/FN needles. All generated plans were normalized to the same D90 of the clinically treated plans.

For the plans in category a), DMBT generally outperformed T&R with average reduction in D2cc of -2.39%, -5.21%, and -2.69% for bladder, rectum, and sigmoid, respectively. For the plans in category b) and c), DMBT generally outperformed T&R if the same needles in AN/FN were utilized in both cases with average reduction in D2cc of -1.82%, -3.40%, and -6.04%, respectively. For the cases where the needles were not utilized for both applicators, an average D2cc reduction of -7.45%, -7.61%, and 17.47% were observed, respectively.

Under the same clinical conditions, with/without needles, the DMBT applicator tends to generate more favorable plans compared with the conventional T&R applicator, and hence, is a promising technology.

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