Program Information
I-125 Seed Implant Brachytherapy in Large Prostates and Dosimetric Outcomes
S PRAMANIK1,2*, J BRICENO1,2 , H GIESCHEN1,2 , E IZAGUIRRE1,2,3 , (1) Methodist University Hospital, (2) West Cancer Center, and (3) University of Tennessee Health Science Center, Memphis, TN.
Presentations
WE-RAM2-GePD-J(B)-2 (Wednesday, August 2, 2017) 10:00 AM - 10:30 AM Room: Joint Imaging-Therapy ePoster Lounge - B
Purpose: A comprehensive review of I-125 seed implant brachytherapy with focus in large prostate cases to investigate dosimetric outcomes by comparing pre-implant dosimetry to that of post-implant as a measure of treatment quality.
Methods: Patient’s prostate sizes vary from as low as 15cc to over 100cc. Our study focuses on LDR brachytherapy of large prostates with a volume larger than 50cc. Per ABS consensus guidelines, “…practitioners with limited experience should avoid permanent prostate brachytherapy on large prostates”. Our study includes 164 patients; 85(52%) with prostate sizes less than 40cc, 52(31%) with 40-50 cc and 27(17 %) with more than 50cc. For patient selection, planning and evaluation, we used our in-house protocol (which includes dosimetric parameters recommended by American Brachytherapy Society, AAPM TG-43 protocol and the European Society of Radiotherapy and Oncology). Patient’s age ranged from 52 to 78 (median 66) and stage from T1c to T2a. Implant dosimetry was performed using VariSeed V8.02 Brachytherapy Planning System and intra-operative TRUS images. VariSeed auto plan was manually modified with peripheral loading techniques and pre-implant and post-implant (one month following implant) data were reviewed to assess treatment quality.
Results: For large prostate patient population, the average prostate size was 56 cc per trans-rectal ultrasound and 58.3 per post-op CT. Prostate average prePlan V100 was 98.1% vs. postPlan V100 90.1% and average prePlan D90 was 119.5 % vs. postPlan D90 102.3%. Urethra D1% and rectum V100 (cc) dose per protocol were limited to 150% and 2 cc respectively. Rectal V100 was 0.26 cc for preplan and 1.32 cc for postPlan. Post-Implant bladder dose was D90% <5% of the Rx dose and V100 was 0.14 cc.
Conclusion: Radioactive seed implant is an effective treatment option for early stage prostate cancer of large prostates. Post-implant study shows a rectal dose increase with respect to preplan dosimetry.
Contact Email: