Vinita Takiar1, Thomas J Pugh1, David Swanson2, Rajat J Kudchadker3, Teresa L Bruno3, Sarah McAvoy1, Usama Mahmood1, Steven J Frank4. 1. Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX. 2. Department of Urology, The University of Texas MD Anderson Cancer Center, Houston, TX. 3. Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, TX. 4. Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX. Electronic address: sjfrank@mdanderson.org.
Abstract
PURPOSE: Palladium-103 ((103)Pd) may be superior to other isotopes in brachytherapy for localized intermediate-risk prostate cancer because of its relatively short half-life, higher initial dose rate, and greater dose heterogeneity within the target volume; these properties also underscore the need for accurate target delineation and postimplant quality assurance. We assessed the use of prostate sector analysis based on MRI for quality assurance after (103)Pd monotherapy. METHODS AND MATERIALS: Fifty men with intermediate-risk prostate cancer underwent (103)Pd monotherapy in a prospective phase II trial at MD Anderson Cancer Center. Dosimetric analyses on day 30 after the implant were done using both CT and fused CT/MRI scans. Dosimetric variables were assessed for the entire prostate and for each of three or six sectors. Volumes and dosimetric variables were compared with paired t tests. RESULTS: Postimplant dosimetric variables for the entire prostate were significantly different on CT vs. CT/MRI (p = 0.019 for V100 and p < 0.01 for D90). Prostate volumes were smaller on the CT/MRI scans (p < 0.00001). The base sector contributed the greatest difference, with doses based on CT/MRI lower than those based on CT (p < 0.01 for V100 and D90). To date, these lower base doses have not affected biochemical outcomes for patients with disease in prostate base biopsy samples. CONCLUSIONS: CT/MRI is more precise than CT for prostate volume delineation and dosimetric quality assessment and thus provides superior heterogeneity control assessment after (103)Pd monotherapy implants.
PURPOSE:Palladium-103 ((103)Pd) may be superior to other isotopes in brachytherapy for localized intermediate-risk prostate cancer because of its relatively short half-life, higher initial dose rate, and greater dose heterogeneity within the target volume; these properties also underscore the need for accurate target delineation and postimplant quality assurance. We assessed the use of prostate sector analysis based on MRI for quality assurance after (103)Pd monotherapy. METHODS AND MATERIALS: Fifty men with intermediate-risk prostate cancer underwent (103)Pd monotherapy in a prospective phase II trial at MD Anderson Cancer Center. Dosimetric analyses on day 30 after the implant were done using both CT and fused CT/MRI scans. Dosimetric variables were assessed for the entire prostate and for each of three or six sectors. Volumes and dosimetric variables were compared with paired t tests. RESULTS: Postimplant dosimetric variables for the entire prostate were significantly different on CT vs. CT/MRI (p = 0.019 for V100 and p < 0.01 for D90). Prostate volumes were smaller on the CT/MRI scans (p < 0.00001). The base sector contributed the greatest difference, with doses based on CT/MRI lower than those based on CT (p < 0.01 for V100 and D90). To date, these lower base doses have not affected biochemical outcomes for patients with disease in prostate base biopsy samples. CONCLUSIONS: CT/MRI is more precise than CT for prostate volume delineation and dosimetric quality assessment and thus provides superior heterogeneity control assessment after (103)Pd monotherapy implants.
Authors: Geoffrey V Martin; Thomas J Pugh; Usama Mahmood; Rajat J Kudchadker; Jihong Wang; Teresa L Bruno; Tharakeswara Bathala; Pierre Blanchard; Steven J Frank Journal: Brachytherapy Date: 2017-05-10 Impact factor: 2.362