ABSTRACT
PURPOSE: The purpose of this study was to evaluate the influence of potential contributing factors to the incidence of seed slippage and quality of prostate brachytherapy dosimetry comparing "coated" vs. "bare" seeds with a Mick applicator. METHODS AND MATERIALS: Two consecutive groups of 89 patients were treated with (125)I prostate brachytherapy at a high treatment volume single institution. All the patients were evaluated with Day 0 plain films of the pelvis and CT-based dosimetry analysis. The incidence of seed slippage was quantified. The seed slippage outcome was evaluated with respect to source type (bare vs. coated). The Day 0 prostate V(100), V(150), D90%, rectal V(100), and urethra D(30) outcomes were evaluated with respect to source type. RESULTS: A total of 13,512 seeds were placed in 178 patients. An average of 76 seeds and 16 needles were used for each patient. The bare seed group was significantly higher on fluoroscopy minutes (2.34 vs. 1.58 min), seed slippage (5 vs. 1.5 mm), volume of rectum receiving 100% of dose (0.05 vs. 0.0 cc), dose percentage received by 30% of urethra (119% vs. 113.64%), and volume of prostate receiving 100% of prescription dose (95.21% vs. 92.8%). No significant differences in volume of prostate receiving 150% of prescription dose, dose percentage received by 90% of prostate, vascular seed migration, or operating room procedure time were seen. No seed drift greater than 10mm outside the "packet" of other seeds was seen in the AnchorSeed (BrachySciences, a division of Biocompatibles, Inc. Oxford, CT) cohort. CONCLUSION: The report is the first to show the unique "fixity" of AnchorSeed to remain in position after deployment from the Mick applicator. Minimizing seed drag can reduce dose to the penile bulb, and maximize radiation coverage to the apex of the gland.
