(Sunday, 7/12/2020) [Eastern Time (GMT-4)]
Room: AAPM ePoster Library
Purpose: Breast conserving surgery followed by adjuvant irradiation for local regional control is very attractive treatment of choice for young women diagnosed with early stage breast cancer. In this project we explored an innovative approach for partial breast treatment with stranded Yb-169 seeds with SAVI applicator as temporary implant.
Methods: Partial breast irradiation with Ir-192 (HDR) brachytherapy offers compact course of radiation due to limited number of fractions. SAVI applicator which has 6, 8 or 10 peripheral source channels with one center channel. In HDR treatment each channel has different dwell positions depending upon desired dose coverage. In this project pre-planning approach is used to load each SAVI channel with stranded Yb-169 seeds to deliver 45Gy to target volume in 72 hours as temporary implant.
Ytterbium-169(Yb-169) radioactive seeds have promising application in brachytherapy due to an average energy of 93 keV and a half-life of 32 days. TG-43U1 parameters of Yb-169 sources were entered in Pinnacle treatment planning system. In this project six previously treated patients planned with Oncentra and treated on Micro Selectron HDR unit with SAVI applicator were re-planned using Pinnacle Treatment planning system as a temporary implant to deliver 45Gy in 72 hours.
Results: Dosimetric parameters V200, V150, V100, D95, D90 of partial Breast implant with Yb-169 are compared with values obtained from Oncentra planning system for each patient. Excellent target coverage was achieved by using Yb-169 seeds.
Conclusion: SAVI applicator with its multiple peripheral catheters allows placement of stranded Yb-169 seeds. Pre-loaded stranded seeds provide high conformity for target while minimizing radiation to normal tissue as compared to Ir-192 HDR implant. Stranded Yb-169 seed breast implants is safe and convenient treatment option for early stage breast cancer patients. Low energy and short half-life of Yb-169 makes it more attractive over for the proposed use.
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