PV QA 1 - Poster Viewing Q&A 1
SU_27_2274 - Intraoperative Dynamic Dosimetry Using Registered Ultrasound and Fluoroscopy Improves Prostate Brachytherapy Dose Coverage Without Increasing Dose to Normal Tissues
Sunday, October 21
1:15 PM - 2:45 PM
Location: Innovation Hub, Exhibit Hall 3
Intraoperative Dynamic Dosimetry Using Registered Ultrasound and Fluoroscopy Improves Prostate Brachytherapy Dose Coverage Without Increasing Dose to Normal Tissues
S. Z. Hazell1, M. Zahurak2, J. Lee1, T. L. DeWeese1, and D. Song1; 1Johns Hopkins University School of Medicine, Department of Radiation Oncology and Molecular Radiation Sciences, Baltimore, MD, 2Johns Hopkins University School of Medicine, Department of Oncology, Biostatistics, Baltimore, MD
Purpose/Objective(s): Intraoperative registered ultrasound and fluoroscopy (iRUF) is a technique for intraoperative dosimetry and adaptive plan modification using 3D reconstruction of source positions from C-arm fluoroscopy. The aim is to intraoperatively detect cold spots and improve prostate coverage prior to completion of implant with targeted addition of seeds if needed. Our hypothesis is that patients treated with iRUF have improved prostate post-implant dosimetry compared to those treated without iRUF and that such improvements are not associated with greater rates of exceeding normal tissue constraints.
Materials/Methods: We utilized iRUF in two prospective, single-arm IRB-approved trials (phase I and phase II), between 2007 and 2017, but have not previously compared those results against patients treated without iRUF. We now compare these iRUF protocol patients with patients treated using standard intraoperative transrectal ultrasound (TRUS)-based seed tracking, whose data are within an IRB-approved prospective database. All patients received Pd-103 implants and had post-implant Day 1 CT/MRI fusion-based assessment of dose to prostate, urethra (with catheter), and rectum. Dosimetric values for those treated with and without iRUF were compared using Wilcoxon test and Fisher’s Exact tests.
Results: A total 217 patients, 52 patients treated with iRUF vs 165 treated without iRUF, were analyzed. Median prostate volume was similar between the groups (36.1cc vs 39.7cc, p=0.12). 96% of patients treated with iRUF met a goal of prostate V100 >95% vs 60% of patients treated without iRUF (p<.0001). 100% of iRUF patients vs 90% of non-iRUF patients had prostate D90 >90% (p=0.01). Median prostate V150 for those treated with iRUF was only slightly increased, at 71% vs 67% (p=0.02), whereas V200 was similar (42% vs 40%, p=0.24). Urethra sparing of D5<160% was achieved in 83% vs 73% (p=0.2) of patients treated with and without iRUF; urethra D30<140% constraint was met in 83% vs 82% (p=1.0) of patients treated with and without iRUF, respectively. Rectal V100 <1.0 cc was achieved in all patients treated with iRUF vs 96% of patients treated without iRUF (p=0.34).
Conclusion: iRUF is a technique developed for intraoperative improvement of prostate coverage through adaptive plan modification. In this comparison of prospective data, use of iRUF is associated with improved prostate coverage compared to standard TRUS-based seed tracking while maintaining similar sparing of urethra and rectum.
Author Disclosure: S.Z. Hazell: None. M. Zahurak: None. J. Lee: None. T.L. DeWeese: None. D. Song: Stock; Roche.